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2547 lines
61 KiB
2547 lines
61 KiB
/* |
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* zsmalloc memory allocator |
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* |
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* Copyright (C) 2011 Nitin Gupta |
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* Copyright (C) 2012, 2013 Minchan Kim |
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* |
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* This code is released using a dual license strategy: BSD/GPL |
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* You can choose the license that better fits your requirements. |
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* |
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* Released under the terms of 3-clause BSD License |
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* Released under the terms of GNU General Public License Version 2.0 |
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*/ |
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|
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/* |
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* Following is how we use various fields and flags of underlying |
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* struct page(s) to form a zspage. |
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* |
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* Usage of struct page fields: |
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* page->private: points to zspage |
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* page->freelist(index): links together all component pages of a zspage |
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* For the huge page, this is always 0, so we use this field |
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* to store handle. |
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* page->units: first object offset in a subpage of zspage |
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* |
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* Usage of struct page flags: |
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* PG_private: identifies the first component page |
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* PG_owner_priv_1: identifies the huge component page |
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* |
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*/ |
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|
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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|
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#include <linux/module.h> |
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#include <linux/kernel.h> |
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#include <linux/sched.h> |
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#include <linux/magic.h> |
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#include <linux/bitops.h> |
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#include <linux/errno.h> |
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#include <linux/highmem.h> |
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#include <linux/string.h> |
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#include <linux/slab.h> |
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#include <linux/pgtable.h> |
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#include <asm/tlbflush.h> |
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#include <linux/cpumask.h> |
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#include <linux/cpu.h> |
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#include <linux/vmalloc.h> |
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#include <linux/preempt.h> |
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#include <linux/spinlock.h> |
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#include <linux/shrinker.h> |
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#include <linux/types.h> |
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#include <linux/debugfs.h> |
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#include <linux/zsmalloc.h> |
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#include <linux/zpool.h> |
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#include <linux/mount.h> |
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#include <linux/pseudo_fs.h> |
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#include <linux/migrate.h> |
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#include <linux/wait.h> |
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#include <linux/pagemap.h> |
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#include <linux/fs.h> |
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#define ZSPAGE_MAGIC 0x58 |
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|
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/* |
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* This must be power of 2 and greater than of equal to sizeof(link_free). |
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* These two conditions ensure that any 'struct link_free' itself doesn't |
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* span more than 1 page which avoids complex case of mapping 2 pages simply |
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* to restore link_free pointer values. |
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*/ |
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#define ZS_ALIGN 8 |
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|
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/* |
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* A single 'zspage' is composed of up to 2^N discontiguous 0-order (single) |
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* pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N. |
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*/ |
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#define ZS_MAX_ZSPAGE_ORDER 2 |
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#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER) |
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|
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#define ZS_HANDLE_SIZE (sizeof(unsigned long)) |
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|
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/* |
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* Object location (<PFN>, <obj_idx>) is encoded as |
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* a single (unsigned long) handle value. |
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* |
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* Note that object index <obj_idx> starts from 0. |
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* |
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* This is made more complicated by various memory models and PAE. |
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*/ |
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|
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#ifndef MAX_POSSIBLE_PHYSMEM_BITS |
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#ifdef MAX_PHYSMEM_BITS |
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#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS |
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#else |
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/* |
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* If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just |
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* be PAGE_SHIFT |
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*/ |
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#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG |
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#endif |
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#endif |
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#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) |
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|
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/* |
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* Memory for allocating for handle keeps object position by |
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* encoding <page, obj_idx> and the encoded value has a room |
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* in least bit(ie, look at obj_to_location). |
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* We use the bit to synchronize between object access by |
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* user and migration. |
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*/ |
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#define HANDLE_PIN_BIT 0 |
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|
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/* |
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* Head in allocated object should have OBJ_ALLOCATED_TAG |
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* to identify the object was allocated or not. |
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* It's okay to add the status bit in the least bit because |
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* header keeps handle which is 4byte-aligned address so we |
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* have room for two bit at least. |
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*/ |
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#define OBJ_ALLOCATED_TAG 1 |
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#define OBJ_TAG_BITS 1 |
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#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) |
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#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) |
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#define FULLNESS_BITS 2 |
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#define CLASS_BITS 8 |
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#define ISOLATED_BITS 3 |
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#define MAGIC_VAL_BITS 8 |
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#define MAX(a, b) ((a) >= (b) ? (a) : (b)) |
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/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */ |
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#define ZS_MIN_ALLOC_SIZE \ |
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MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS)) |
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/* each chunk includes extra space to keep handle */ |
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#define ZS_MAX_ALLOC_SIZE PAGE_SIZE |
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|
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/* |
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* On systems with 4K page size, this gives 255 size classes! There is a |
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* trader-off here: |
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* - Large number of size classes is potentially wasteful as free page are |
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* spread across these classes |
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* - Small number of size classes causes large internal fragmentation |
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* - Probably its better to use specific size classes (empirically |
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* determined). NOTE: all those class sizes must be set as multiple of |
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* ZS_ALIGN to make sure link_free itself never has to span 2 pages. |
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* |
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* ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN |
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* (reason above) |
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*/ |
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#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS) |
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#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \ |
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ZS_SIZE_CLASS_DELTA) + 1) |
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enum fullness_group { |
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ZS_EMPTY, |
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ZS_ALMOST_EMPTY, |
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ZS_ALMOST_FULL, |
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ZS_FULL, |
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NR_ZS_FULLNESS, |
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}; |
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enum zs_stat_type { |
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CLASS_EMPTY, |
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CLASS_ALMOST_EMPTY, |
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CLASS_ALMOST_FULL, |
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CLASS_FULL, |
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OBJ_ALLOCATED, |
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OBJ_USED, |
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NR_ZS_STAT_TYPE, |
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}; |
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|
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struct zs_size_stat { |
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unsigned long objs[NR_ZS_STAT_TYPE]; |
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}; |
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#ifdef CONFIG_ZSMALLOC_STAT |
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static struct dentry *zs_stat_root; |
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#endif |
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|
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#ifdef CONFIG_COMPACTION |
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static struct vfsmount *zsmalloc_mnt; |
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#endif |
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/* |
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* We assign a page to ZS_ALMOST_EMPTY fullness group when: |
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* n <= N / f, where |
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* n = number of allocated objects |
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* N = total number of objects zspage can store |
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* f = fullness_threshold_frac |
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* |
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* Similarly, we assign zspage to: |
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* ZS_ALMOST_FULL when n > N / f |
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* ZS_EMPTY when n == 0 |
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* ZS_FULL when n == N |
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* |
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* (see: fix_fullness_group()) |
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*/ |
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static const int fullness_threshold_frac = 4; |
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static size_t huge_class_size; |
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|
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struct size_class { |
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spinlock_t lock; |
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struct list_head fullness_list[NR_ZS_FULLNESS]; |
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/* |
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* Size of objects stored in this class. Must be multiple |
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* of ZS_ALIGN. |
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*/ |
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int size; |
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int objs_per_zspage; |
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/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */ |
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int pages_per_zspage; |
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|
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unsigned int index; |
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struct zs_size_stat stats; |
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}; |
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/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */ |
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static void SetPageHugeObject(struct page *page) |
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{ |
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SetPageOwnerPriv1(page); |
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} |
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static void ClearPageHugeObject(struct page *page) |
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{ |
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ClearPageOwnerPriv1(page); |
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} |
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static int PageHugeObject(struct page *page) |
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{ |
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return PageOwnerPriv1(page); |
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} |
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|
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/* |
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* Placed within free objects to form a singly linked list. |
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* For every zspage, zspage->freeobj gives head of this list. |
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* |
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* This must be power of 2 and less than or equal to ZS_ALIGN |
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*/ |
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struct link_free { |
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union { |
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/* |
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* Free object index; |
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* It's valid for non-allocated object |
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*/ |
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unsigned long next; |
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/* |
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* Handle of allocated object. |
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*/ |
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unsigned long handle; |
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}; |
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}; |
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struct zs_pool { |
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const char *name; |
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|
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struct size_class *size_class[ZS_SIZE_CLASSES]; |
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struct kmem_cache *handle_cachep; |
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struct kmem_cache *zspage_cachep; |
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|
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atomic_long_t pages_allocated; |
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|
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struct zs_pool_stats stats; |
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|
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/* Compact classes */ |
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struct shrinker shrinker; |
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#ifdef CONFIG_ZSMALLOC_STAT |
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struct dentry *stat_dentry; |
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#endif |
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#ifdef CONFIG_COMPACTION |
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struct inode *inode; |
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struct work_struct free_work; |
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/* A wait queue for when migration races with async_free_zspage() */ |
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struct wait_queue_head migration_wait; |
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atomic_long_t isolated_pages; |
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bool destroying; |
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#endif |
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}; |
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struct zspage { |
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struct { |
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unsigned int fullness:FULLNESS_BITS; |
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unsigned int class:CLASS_BITS + 1; |
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unsigned int isolated:ISOLATED_BITS; |
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unsigned int magic:MAGIC_VAL_BITS; |
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}; |
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unsigned int inuse; |
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unsigned int freeobj; |
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struct page *first_page; |
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struct list_head list; /* fullness list */ |
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#ifdef CONFIG_COMPACTION |
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rwlock_t lock; |
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#endif |
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}; |
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struct mapping_area { |
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char *vm_buf; /* copy buffer for objects that span pages */ |
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char *vm_addr; /* address of kmap_atomic()'ed pages */ |
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enum zs_mapmode vm_mm; /* mapping mode */ |
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}; |
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#ifdef CONFIG_COMPACTION |
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static int zs_register_migration(struct zs_pool *pool); |
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static void zs_unregister_migration(struct zs_pool *pool); |
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static void migrate_lock_init(struct zspage *zspage); |
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static void migrate_read_lock(struct zspage *zspage); |
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static void migrate_read_unlock(struct zspage *zspage); |
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static void kick_deferred_free(struct zs_pool *pool); |
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static void init_deferred_free(struct zs_pool *pool); |
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static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage); |
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#else |
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static int zsmalloc_mount(void) { return 0; } |
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static void zsmalloc_unmount(void) {} |
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static int zs_register_migration(struct zs_pool *pool) { return 0; } |
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static void zs_unregister_migration(struct zs_pool *pool) {} |
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static void migrate_lock_init(struct zspage *zspage) {} |
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static void migrate_read_lock(struct zspage *zspage) {} |
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static void migrate_read_unlock(struct zspage *zspage) {} |
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static void kick_deferred_free(struct zs_pool *pool) {} |
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static void init_deferred_free(struct zs_pool *pool) {} |
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static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {} |
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#endif |
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static int create_cache(struct zs_pool *pool) |
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{ |
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pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE, |
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0, 0, NULL); |
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if (!pool->handle_cachep) |
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return 1; |
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pool->zspage_cachep = kmem_cache_create("zspage", sizeof(struct zspage), |
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0, 0, NULL); |
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if (!pool->zspage_cachep) { |
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kmem_cache_destroy(pool->handle_cachep); |
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pool->handle_cachep = NULL; |
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return 1; |
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} |
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return 0; |
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} |
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static void destroy_cache(struct zs_pool *pool) |
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{ |
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kmem_cache_destroy(pool->handle_cachep); |
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kmem_cache_destroy(pool->zspage_cachep); |
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} |
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static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp) |
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{ |
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return (unsigned long)kmem_cache_alloc(pool->handle_cachep, |
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gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE)); |
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} |
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static void cache_free_handle(struct zs_pool *pool, unsigned long handle) |
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{ |
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kmem_cache_free(pool->handle_cachep, (void *)handle); |
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} |
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|
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static struct zspage *cache_alloc_zspage(struct zs_pool *pool, gfp_t flags) |
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{ |
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return kmem_cache_zalloc(pool->zspage_cachep, |
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flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE)); |
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} |
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|
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static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage) |
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{ |
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kmem_cache_free(pool->zspage_cachep, zspage); |
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} |
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static void record_obj(unsigned long handle, unsigned long obj) |
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{ |
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/* |
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* lsb of @obj represents handle lock while other bits |
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* represent object value the handle is pointing so |
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* updating shouldn't do store tearing. |
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*/ |
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WRITE_ONCE(*(unsigned long *)handle, obj); |
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} |
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|
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/* zpool driver */ |
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|
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#ifdef CONFIG_ZPOOL |
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|
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static void *zs_zpool_create(const char *name, gfp_t gfp, |
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const struct zpool_ops *zpool_ops, |
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struct zpool *zpool) |
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{ |
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/* |
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* Ignore global gfp flags: zs_malloc() may be invoked from |
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* different contexts and its caller must provide a valid |
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* gfp mask. |
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*/ |
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return zs_create_pool(name); |
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} |
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static void zs_zpool_destroy(void *pool) |
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{ |
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zs_destroy_pool(pool); |
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} |
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static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp, |
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unsigned long *handle) |
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{ |
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*handle = zs_malloc(pool, size, gfp); |
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return *handle ? 0 : -1; |
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} |
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static void zs_zpool_free(void *pool, unsigned long handle) |
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{ |
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zs_free(pool, handle); |
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} |
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|
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static void *zs_zpool_map(void *pool, unsigned long handle, |
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enum zpool_mapmode mm) |
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{ |
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enum zs_mapmode zs_mm; |
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|
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switch (mm) { |
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case ZPOOL_MM_RO: |
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zs_mm = ZS_MM_RO; |
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break; |
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case ZPOOL_MM_WO: |
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zs_mm = ZS_MM_WO; |
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break; |
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case ZPOOL_MM_RW: |
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default: |
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zs_mm = ZS_MM_RW; |
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break; |
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} |
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|
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return zs_map_object(pool, handle, zs_mm); |
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} |
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static void zs_zpool_unmap(void *pool, unsigned long handle) |
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{ |
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zs_unmap_object(pool, handle); |
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} |
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|
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static u64 zs_zpool_total_size(void *pool) |
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{ |
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return zs_get_total_pages(pool) << PAGE_SHIFT; |
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} |
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|
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static struct zpool_driver zs_zpool_driver = { |
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.type = "zsmalloc", |
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.owner = THIS_MODULE, |
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.create = zs_zpool_create, |
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.destroy = zs_zpool_destroy, |
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.malloc_support_movable = true, |
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.malloc = zs_zpool_malloc, |
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.free = zs_zpool_free, |
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.map = zs_zpool_map, |
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.unmap = zs_zpool_unmap, |
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.total_size = zs_zpool_total_size, |
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}; |
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|
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MODULE_ALIAS("zpool-zsmalloc"); |
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#endif /* CONFIG_ZPOOL */ |
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|
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/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */ |
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static DEFINE_PER_CPU(struct mapping_area, zs_map_area); |
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|
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static bool is_zspage_isolated(struct zspage *zspage) |
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{ |
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return zspage->isolated; |
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} |
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|
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static __maybe_unused int is_first_page(struct page *page) |
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{ |
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return PagePrivate(page); |
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} |
|
|
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/* Protected by class->lock */ |
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static inline int get_zspage_inuse(struct zspage *zspage) |
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{ |
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return zspage->inuse; |
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} |
|
|
|
|
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static inline void mod_zspage_inuse(struct zspage *zspage, int val) |
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{ |
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zspage->inuse += val; |
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} |
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|
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static inline struct page *get_first_page(struct zspage *zspage) |
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{ |
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struct page *first_page = zspage->first_page; |
|
|
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VM_BUG_ON_PAGE(!is_first_page(first_page), first_page); |
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return first_page; |
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} |
|
|
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static inline int get_first_obj_offset(struct page *page) |
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{ |
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return page->units; |
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} |
|
|
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static inline void set_first_obj_offset(struct page *page, int offset) |
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{ |
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page->units = offset; |
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} |
|
|
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static inline unsigned int get_freeobj(struct zspage *zspage) |
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{ |
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return zspage->freeobj; |
|
} |
|
|
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static inline void set_freeobj(struct zspage *zspage, unsigned int obj) |
|
{ |
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zspage->freeobj = obj; |
|
} |
|
|
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static void get_zspage_mapping(struct zspage *zspage, |
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unsigned int *class_idx, |
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enum fullness_group *fullness) |
|
{ |
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BUG_ON(zspage->magic != ZSPAGE_MAGIC); |
|
|
|
*fullness = zspage->fullness; |
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*class_idx = zspage->class; |
|
} |
|
|
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static void set_zspage_mapping(struct zspage *zspage, |
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unsigned int class_idx, |
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enum fullness_group fullness) |
|
{ |
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zspage->class = class_idx; |
|
zspage->fullness = fullness; |
|
} |
|
|
|
/* |
|
* zsmalloc divides the pool into various size classes where each |
|
* class maintains a list of zspages where each zspage is divided |
|
* into equal sized chunks. Each allocation falls into one of these |
|
* classes depending on its size. This function returns index of the |
|
* size class which has chunk size big enough to hold the give size. |
|
*/ |
|
static int get_size_class_index(int size) |
|
{ |
|
int idx = 0; |
|
|
|
if (likely(size > ZS_MIN_ALLOC_SIZE)) |
|
idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE, |
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ZS_SIZE_CLASS_DELTA); |
|
|
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return min_t(int, ZS_SIZE_CLASSES - 1, idx); |
|
} |
|
|
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/* type can be of enum type zs_stat_type or fullness_group */ |
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static inline void zs_stat_inc(struct size_class *class, |
|
int type, unsigned long cnt) |
|
{ |
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class->stats.objs[type] += cnt; |
|
} |
|
|
|
/* type can be of enum type zs_stat_type or fullness_group */ |
|
static inline void zs_stat_dec(struct size_class *class, |
|
int type, unsigned long cnt) |
|
{ |
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class->stats.objs[type] -= cnt; |
|
} |
|
|
|
/* type can be of enum type zs_stat_type or fullness_group */ |
|
static inline unsigned long zs_stat_get(struct size_class *class, |
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int type) |
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{ |
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return class->stats.objs[type]; |
|
} |
|
|
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#ifdef CONFIG_ZSMALLOC_STAT |
|
|
|
static void __init zs_stat_init(void) |
|
{ |
|
if (!debugfs_initialized()) { |
|
pr_warn("debugfs not available, stat dir not created\n"); |
|
return; |
|
} |
|
|
|
zs_stat_root = debugfs_create_dir("zsmalloc", NULL); |
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} |
|
|
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static void __exit zs_stat_exit(void) |
|
{ |
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debugfs_remove_recursive(zs_stat_root); |
|
} |
|
|
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static unsigned long zs_can_compact(struct size_class *class); |
|
|
|
static int zs_stats_size_show(struct seq_file *s, void *v) |
|
{ |
|
int i; |
|
struct zs_pool *pool = s->private; |
|
struct size_class *class; |
|
int objs_per_zspage; |
|
unsigned long class_almost_full, class_almost_empty; |
|
unsigned long obj_allocated, obj_used, pages_used, freeable; |
|
unsigned long total_class_almost_full = 0, total_class_almost_empty = 0; |
|
unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0; |
|
unsigned long total_freeable = 0; |
|
|
|
seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s %8s\n", |
|
"class", "size", "almost_full", "almost_empty", |
|
"obj_allocated", "obj_used", "pages_used", |
|
"pages_per_zspage", "freeable"); |
|
|
|
for (i = 0; i < ZS_SIZE_CLASSES; i++) { |
|
class = pool->size_class[i]; |
|
|
|
if (class->index != i) |
|
continue; |
|
|
|
spin_lock(&class->lock); |
|
class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL); |
|
class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY); |
|
obj_allocated = zs_stat_get(class, OBJ_ALLOCATED); |
|
obj_used = zs_stat_get(class, OBJ_USED); |
|
freeable = zs_can_compact(class); |
|
spin_unlock(&class->lock); |
|
|
|
objs_per_zspage = class->objs_per_zspage; |
|
pages_used = obj_allocated / objs_per_zspage * |
|
class->pages_per_zspage; |
|
|
|
seq_printf(s, " %5u %5u %11lu %12lu %13lu" |
|
" %10lu %10lu %16d %8lu\n", |
|
i, class->size, class_almost_full, class_almost_empty, |
|
obj_allocated, obj_used, pages_used, |
|
class->pages_per_zspage, freeable); |
|
|
|
total_class_almost_full += class_almost_full; |
|
total_class_almost_empty += class_almost_empty; |
|
total_objs += obj_allocated; |
|
total_used_objs += obj_used; |
|
total_pages += pages_used; |
|
total_freeable += freeable; |
|
} |
|
|
|
seq_puts(s, "\n"); |
|
seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu %16s %8lu\n", |
|
"Total", "", total_class_almost_full, |
|
total_class_almost_empty, total_objs, |
|
total_used_objs, total_pages, "", total_freeable); |
|
|
|
return 0; |
|
} |
|
DEFINE_SHOW_ATTRIBUTE(zs_stats_size); |
|
|
|
static void zs_pool_stat_create(struct zs_pool *pool, const char *name) |
|
{ |
|
if (!zs_stat_root) { |
|
pr_warn("no root stat dir, not creating <%s> stat dir\n", name); |
|
return; |
|
} |
|
|
|
pool->stat_dentry = debugfs_create_dir(name, zs_stat_root); |
|
|
|
debugfs_create_file("classes", S_IFREG | 0444, pool->stat_dentry, pool, |
|
&zs_stats_size_fops); |
|
} |
|
|
|
static void zs_pool_stat_destroy(struct zs_pool *pool) |
|
{ |
|
debugfs_remove_recursive(pool->stat_dentry); |
|
} |
|
|
|
#else /* CONFIG_ZSMALLOC_STAT */ |
|
static void __init zs_stat_init(void) |
|
{ |
|
} |
|
|
|
static void __exit zs_stat_exit(void) |
|
{ |
|
} |
|
|
|
static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name) |
|
{ |
|
} |
|
|
|
static inline void zs_pool_stat_destroy(struct zs_pool *pool) |
|
{ |
|
} |
|
#endif |
|
|
|
|
|
/* |
|
* For each size class, zspages are divided into different groups |
|
* depending on how "full" they are. This was done so that we could |
|
* easily find empty or nearly empty zspages when we try to shrink |
|
* the pool (not yet implemented). This function returns fullness |
|
* status of the given page. |
|
*/ |
|
static enum fullness_group get_fullness_group(struct size_class *class, |
|
struct zspage *zspage) |
|
{ |
|
int inuse, objs_per_zspage; |
|
enum fullness_group fg; |
|
|
|
inuse = get_zspage_inuse(zspage); |
|
objs_per_zspage = class->objs_per_zspage; |
|
|
|
if (inuse == 0) |
|
fg = ZS_EMPTY; |
|
else if (inuse == objs_per_zspage) |
|
fg = ZS_FULL; |
|
else if (inuse <= 3 * objs_per_zspage / fullness_threshold_frac) |
|
fg = ZS_ALMOST_EMPTY; |
|
else |
|
fg = ZS_ALMOST_FULL; |
|
|
|
return fg; |
|
} |
|
|
|
/* |
|
* Each size class maintains various freelists and zspages are assigned |
|
* to one of these freelists based on the number of live objects they |
|
* have. This functions inserts the given zspage into the freelist |
|
* identified by <class, fullness_group>. |
|
*/ |
|
static void insert_zspage(struct size_class *class, |
|
struct zspage *zspage, |
|
enum fullness_group fullness) |
|
{ |
|
struct zspage *head; |
|
|
|
zs_stat_inc(class, fullness, 1); |
|
head = list_first_entry_or_null(&class->fullness_list[fullness], |
|
struct zspage, list); |
|
/* |
|
* We want to see more ZS_FULL pages and less almost empty/full. |
|
* Put pages with higher ->inuse first. |
|
*/ |
|
if (head && get_zspage_inuse(zspage) < get_zspage_inuse(head)) |
|
list_add(&zspage->list, &head->list); |
|
else |
|
list_add(&zspage->list, &class->fullness_list[fullness]); |
|
} |
|
|
|
/* |
|
* This function removes the given zspage from the freelist identified |
|
* by <class, fullness_group>. |
|
*/ |
|
static void remove_zspage(struct size_class *class, |
|
struct zspage *zspage, |
|
enum fullness_group fullness) |
|
{ |
|
VM_BUG_ON(list_empty(&class->fullness_list[fullness])); |
|
VM_BUG_ON(is_zspage_isolated(zspage)); |
|
|
|
list_del_init(&zspage->list); |
|
zs_stat_dec(class, fullness, 1); |
|
} |
|
|
|
/* |
|
* Each size class maintains zspages in different fullness groups depending |
|
* on the number of live objects they contain. When allocating or freeing |
|
* objects, the fullness status of the page can change, say, from ALMOST_FULL |
|
* to ALMOST_EMPTY when freeing an object. This function checks if such |
|
* a status change has occurred for the given page and accordingly moves the |
|
* page from the freelist of the old fullness group to that of the new |
|
* fullness group. |
|
*/ |
|
static enum fullness_group fix_fullness_group(struct size_class *class, |
|
struct zspage *zspage) |
|
{ |
|
int class_idx; |
|
enum fullness_group currfg, newfg; |
|
|
|
get_zspage_mapping(zspage, &class_idx, &currfg); |
|
newfg = get_fullness_group(class, zspage); |
|
if (newfg == currfg) |
|
goto out; |
|
|
|
if (!is_zspage_isolated(zspage)) { |
|
remove_zspage(class, zspage, currfg); |
|
insert_zspage(class, zspage, newfg); |
|
} |
|
|
|
set_zspage_mapping(zspage, class_idx, newfg); |
|
|
|
out: |
|
return newfg; |
|
} |
|
|
|
/* |
|
* We have to decide on how many pages to link together |
|
* to form a zspage for each size class. This is important |
|
* to reduce wastage due to unusable space left at end of |
|
* each zspage which is given as: |
|
* wastage = Zp % class_size |
|
* usage = Zp - wastage |
|
* where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ... |
|
* |
|
* For example, for size class of 3/8 * PAGE_SIZE, we should |
|
* link together 3 PAGE_SIZE sized pages to form a zspage |
|
* since then we can perfectly fit in 8 such objects. |
|
*/ |
|
static int get_pages_per_zspage(int class_size) |
|
{ |
|
int i, max_usedpc = 0; |
|
/* zspage order which gives maximum used size per KB */ |
|
int max_usedpc_order = 1; |
|
|
|
for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) { |
|
int zspage_size; |
|
int waste, usedpc; |
|
|
|
zspage_size = i * PAGE_SIZE; |
|
waste = zspage_size % class_size; |
|
usedpc = (zspage_size - waste) * 100 / zspage_size; |
|
|
|
if (usedpc > max_usedpc) { |
|
max_usedpc = usedpc; |
|
max_usedpc_order = i; |
|
} |
|
} |
|
|
|
return max_usedpc_order; |
|
} |
|
|
|
static struct zspage *get_zspage(struct page *page) |
|
{ |
|
struct zspage *zspage = (struct zspage *)page_private(page); |
|
|
|
BUG_ON(zspage->magic != ZSPAGE_MAGIC); |
|
return zspage; |
|
} |
|
|
|
static struct page *get_next_page(struct page *page) |
|
{ |
|
if (unlikely(PageHugeObject(page))) |
|
return NULL; |
|
|
|
return page->freelist; |
|
} |
|
|
|
/** |
|
* obj_to_location - get (<page>, <obj_idx>) from encoded object value |
|
* @obj: the encoded object value |
|
* @page: page object resides in zspage |
|
* @obj_idx: object index |
|
*/ |
|
static void obj_to_location(unsigned long obj, struct page **page, |
|
unsigned int *obj_idx) |
|
{ |
|
obj >>= OBJ_TAG_BITS; |
|
*page = pfn_to_page(obj >> OBJ_INDEX_BITS); |
|
*obj_idx = (obj & OBJ_INDEX_MASK); |
|
} |
|
|
|
/** |
|
* location_to_obj - get obj value encoded from (<page>, <obj_idx>) |
|
* @page: page object resides in zspage |
|
* @obj_idx: object index |
|
*/ |
|
static unsigned long location_to_obj(struct page *page, unsigned int obj_idx) |
|
{ |
|
unsigned long obj; |
|
|
|
obj = page_to_pfn(page) << OBJ_INDEX_BITS; |
|
obj |= obj_idx & OBJ_INDEX_MASK; |
|
obj <<= OBJ_TAG_BITS; |
|
|
|
return obj; |
|
} |
|
|
|
static unsigned long handle_to_obj(unsigned long handle) |
|
{ |
|
return *(unsigned long *)handle; |
|
} |
|
|
|
static unsigned long obj_to_head(struct page *page, void *obj) |
|
{ |
|
if (unlikely(PageHugeObject(page))) { |
|
VM_BUG_ON_PAGE(!is_first_page(page), page); |
|
return page->index; |
|
} else |
|
return *(unsigned long *)obj; |
|
} |
|
|
|
static inline int testpin_tag(unsigned long handle) |
|
{ |
|
return bit_spin_is_locked(HANDLE_PIN_BIT, (unsigned long *)handle); |
|
} |
|
|
|
static inline int trypin_tag(unsigned long handle) |
|
{ |
|
return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle); |
|
} |
|
|
|
static void pin_tag(unsigned long handle) __acquires(bitlock) |
|
{ |
|
bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle); |
|
} |
|
|
|
static void unpin_tag(unsigned long handle) __releases(bitlock) |
|
{ |
|
bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle); |
|
} |
|
|
|
static void reset_page(struct page *page) |
|
{ |
|
__ClearPageMovable(page); |
|
ClearPagePrivate(page); |
|
set_page_private(page, 0); |
|
page_mapcount_reset(page); |
|
ClearPageHugeObject(page); |
|
page->freelist = NULL; |
|
} |
|
|
|
static int trylock_zspage(struct zspage *zspage) |
|
{ |
|
struct page *cursor, *fail; |
|
|
|
for (cursor = get_first_page(zspage); cursor != NULL; cursor = |
|
get_next_page(cursor)) { |
|
if (!trylock_page(cursor)) { |
|
fail = cursor; |
|
goto unlock; |
|
} |
|
} |
|
|
|
return 1; |
|
unlock: |
|
for (cursor = get_first_page(zspage); cursor != fail; cursor = |
|
get_next_page(cursor)) |
|
unlock_page(cursor); |
|
|
|
return 0; |
|
} |
|
|
|
static void __free_zspage(struct zs_pool *pool, struct size_class *class, |
|
struct zspage *zspage) |
|
{ |
|
struct page *page, *next; |
|
enum fullness_group fg; |
|
unsigned int class_idx; |
|
|
|
get_zspage_mapping(zspage, &class_idx, &fg); |
|
|
|
assert_spin_locked(&class->lock); |
|
|
|
VM_BUG_ON(get_zspage_inuse(zspage)); |
|
VM_BUG_ON(fg != ZS_EMPTY); |
|
|
|
next = page = get_first_page(zspage); |
|
do { |
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
next = get_next_page(page); |
|
reset_page(page); |
|
unlock_page(page); |
|
dec_zone_page_state(page, NR_ZSPAGES); |
|
put_page(page); |
|
page = next; |
|
} while (page != NULL); |
|
|
|
cache_free_zspage(pool, zspage); |
|
|
|
zs_stat_dec(class, OBJ_ALLOCATED, class->objs_per_zspage); |
|
atomic_long_sub(class->pages_per_zspage, |
|
&pool->pages_allocated); |
|
} |
|
|
|
static void free_zspage(struct zs_pool *pool, struct size_class *class, |
|
struct zspage *zspage) |
|
{ |
|
VM_BUG_ON(get_zspage_inuse(zspage)); |
|
VM_BUG_ON(list_empty(&zspage->list)); |
|
|
|
if (!trylock_zspage(zspage)) { |
|
kick_deferred_free(pool); |
|
return; |
|
} |
|
|
|
remove_zspage(class, zspage, ZS_EMPTY); |
|
__free_zspage(pool, class, zspage); |
|
} |
|
|
|
/* Initialize a newly allocated zspage */ |
|
static void init_zspage(struct size_class *class, struct zspage *zspage) |
|
{ |
|
unsigned int freeobj = 1; |
|
unsigned long off = 0; |
|
struct page *page = get_first_page(zspage); |
|
|
|
while (page) { |
|
struct page *next_page; |
|
struct link_free *link; |
|
void *vaddr; |
|
|
|
set_first_obj_offset(page, off); |
|
|
|
vaddr = kmap_atomic(page); |
|
link = (struct link_free *)vaddr + off / sizeof(*link); |
|
|
|
while ((off += class->size) < PAGE_SIZE) { |
|
link->next = freeobj++ << OBJ_TAG_BITS; |
|
link += class->size / sizeof(*link); |
|
} |
|
|
|
/* |
|
* We now come to the last (full or partial) object on this |
|
* page, which must point to the first object on the next |
|
* page (if present) |
|
*/ |
|
next_page = get_next_page(page); |
|
if (next_page) { |
|
link->next = freeobj++ << OBJ_TAG_BITS; |
|
} else { |
|
/* |
|
* Reset OBJ_TAG_BITS bit to last link to tell |
|
* whether it's allocated object or not. |
|
*/ |
|
link->next = -1UL << OBJ_TAG_BITS; |
|
} |
|
kunmap_atomic(vaddr); |
|
page = next_page; |
|
off %= PAGE_SIZE; |
|
} |
|
|
|
set_freeobj(zspage, 0); |
|
} |
|
|
|
static void create_page_chain(struct size_class *class, struct zspage *zspage, |
|
struct page *pages[]) |
|
{ |
|
int i; |
|
struct page *page; |
|
struct page *prev_page = NULL; |
|
int nr_pages = class->pages_per_zspage; |
|
|
|
/* |
|
* Allocate individual pages and link them together as: |
|
* 1. all pages are linked together using page->freelist |
|
* 2. each sub-page point to zspage using page->private |
|
* |
|
* we set PG_private to identify the first page (i.e. no other sub-page |
|
* has this flag set). |
|
*/ |
|
for (i = 0; i < nr_pages; i++) { |
|
page = pages[i]; |
|
set_page_private(page, (unsigned long)zspage); |
|
page->freelist = NULL; |
|
if (i == 0) { |
|
zspage->first_page = page; |
|
SetPagePrivate(page); |
|
if (unlikely(class->objs_per_zspage == 1 && |
|
class->pages_per_zspage == 1)) |
|
SetPageHugeObject(page); |
|
} else { |
|
prev_page->freelist = page; |
|
} |
|
prev_page = page; |
|
} |
|
} |
|
|
|
/* |
|
* Allocate a zspage for the given size class |
|
*/ |
|
static struct zspage *alloc_zspage(struct zs_pool *pool, |
|
struct size_class *class, |
|
gfp_t gfp) |
|
{ |
|
int i; |
|
struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE]; |
|
struct zspage *zspage = cache_alloc_zspage(pool, gfp); |
|
|
|
if (!zspage) |
|
return NULL; |
|
|
|
zspage->magic = ZSPAGE_MAGIC; |
|
migrate_lock_init(zspage); |
|
|
|
for (i = 0; i < class->pages_per_zspage; i++) { |
|
struct page *page; |
|
|
|
page = alloc_page(gfp); |
|
if (!page) { |
|
while (--i >= 0) { |
|
dec_zone_page_state(pages[i], NR_ZSPAGES); |
|
__free_page(pages[i]); |
|
} |
|
cache_free_zspage(pool, zspage); |
|
return NULL; |
|
} |
|
|
|
inc_zone_page_state(page, NR_ZSPAGES); |
|
pages[i] = page; |
|
} |
|
|
|
create_page_chain(class, zspage, pages); |
|
init_zspage(class, zspage); |
|
|
|
return zspage; |
|
} |
|
|
|
static struct zspage *find_get_zspage(struct size_class *class) |
|
{ |
|
int i; |
|
struct zspage *zspage; |
|
|
|
for (i = ZS_ALMOST_FULL; i >= ZS_EMPTY; i--) { |
|
zspage = list_first_entry_or_null(&class->fullness_list[i], |
|
struct zspage, list); |
|
if (zspage) |
|
break; |
|
} |
|
|
|
return zspage; |
|
} |
|
|
|
static inline int __zs_cpu_up(struct mapping_area *area) |
|
{ |
|
/* |
|
* Make sure we don't leak memory if a cpu UP notification |
|
* and zs_init() race and both call zs_cpu_up() on the same cpu |
|
*/ |
|
if (area->vm_buf) |
|
return 0; |
|
area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL); |
|
if (!area->vm_buf) |
|
return -ENOMEM; |
|
return 0; |
|
} |
|
|
|
static inline void __zs_cpu_down(struct mapping_area *area) |
|
{ |
|
kfree(area->vm_buf); |
|
area->vm_buf = NULL; |
|
} |
|
|
|
static void *__zs_map_object(struct mapping_area *area, |
|
struct page *pages[2], int off, int size) |
|
{ |
|
int sizes[2]; |
|
void *addr; |
|
char *buf = area->vm_buf; |
|
|
|
/* disable page faults to match kmap_atomic() return conditions */ |
|
pagefault_disable(); |
|
|
|
/* no read fastpath */ |
|
if (area->vm_mm == ZS_MM_WO) |
|
goto out; |
|
|
|
sizes[0] = PAGE_SIZE - off; |
|
sizes[1] = size - sizes[0]; |
|
|
|
/* copy object to per-cpu buffer */ |
|
addr = kmap_atomic(pages[0]); |
|
memcpy(buf, addr + off, sizes[0]); |
|
kunmap_atomic(addr); |
|
addr = kmap_atomic(pages[1]); |
|
memcpy(buf + sizes[0], addr, sizes[1]); |
|
kunmap_atomic(addr); |
|
out: |
|
return area->vm_buf; |
|
} |
|
|
|
static void __zs_unmap_object(struct mapping_area *area, |
|
struct page *pages[2], int off, int size) |
|
{ |
|
int sizes[2]; |
|
void *addr; |
|
char *buf; |
|
|
|
/* no write fastpath */ |
|
if (area->vm_mm == ZS_MM_RO) |
|
goto out; |
|
|
|
buf = area->vm_buf; |
|
buf = buf + ZS_HANDLE_SIZE; |
|
size -= ZS_HANDLE_SIZE; |
|
off += ZS_HANDLE_SIZE; |
|
|
|
sizes[0] = PAGE_SIZE - off; |
|
sizes[1] = size - sizes[0]; |
|
|
|
/* copy per-cpu buffer to object */ |
|
addr = kmap_atomic(pages[0]); |
|
memcpy(addr + off, buf, sizes[0]); |
|
kunmap_atomic(addr); |
|
addr = kmap_atomic(pages[1]); |
|
memcpy(addr, buf + sizes[0], sizes[1]); |
|
kunmap_atomic(addr); |
|
|
|
out: |
|
/* enable page faults to match kunmap_atomic() return conditions */ |
|
pagefault_enable(); |
|
} |
|
|
|
static int zs_cpu_prepare(unsigned int cpu) |
|
{ |
|
struct mapping_area *area; |
|
|
|
area = &per_cpu(zs_map_area, cpu); |
|
return __zs_cpu_up(area); |
|
} |
|
|
|
static int zs_cpu_dead(unsigned int cpu) |
|
{ |
|
struct mapping_area *area; |
|
|
|
area = &per_cpu(zs_map_area, cpu); |
|
__zs_cpu_down(area); |
|
return 0; |
|
} |
|
|
|
static bool can_merge(struct size_class *prev, int pages_per_zspage, |
|
int objs_per_zspage) |
|
{ |
|
if (prev->pages_per_zspage == pages_per_zspage && |
|
prev->objs_per_zspage == objs_per_zspage) |
|
return true; |
|
|
|
return false; |
|
} |
|
|
|
static bool zspage_full(struct size_class *class, struct zspage *zspage) |
|
{ |
|
return get_zspage_inuse(zspage) == class->objs_per_zspage; |
|
} |
|
|
|
unsigned long zs_get_total_pages(struct zs_pool *pool) |
|
{ |
|
return atomic_long_read(&pool->pages_allocated); |
|
} |
|
EXPORT_SYMBOL_GPL(zs_get_total_pages); |
|
|
|
/** |
|
* zs_map_object - get address of allocated object from handle. |
|
* @pool: pool from which the object was allocated |
|
* @handle: handle returned from zs_malloc |
|
* @mm: maping mode to use |
|
* |
|
* Before using an object allocated from zs_malloc, it must be mapped using |
|
* this function. When done with the object, it must be unmapped using |
|
* zs_unmap_object. |
|
* |
|
* Only one object can be mapped per cpu at a time. There is no protection |
|
* against nested mappings. |
|
* |
|
* This function returns with preemption and page faults disabled. |
|
*/ |
|
void *zs_map_object(struct zs_pool *pool, unsigned long handle, |
|
enum zs_mapmode mm) |
|
{ |
|
struct zspage *zspage; |
|
struct page *page; |
|
unsigned long obj, off; |
|
unsigned int obj_idx; |
|
|
|
unsigned int class_idx; |
|
enum fullness_group fg; |
|
struct size_class *class; |
|
struct mapping_area *area; |
|
struct page *pages[2]; |
|
void *ret; |
|
|
|
/* |
|
* Because we use per-cpu mapping areas shared among the |
|
* pools/users, we can't allow mapping in interrupt context |
|
* because it can corrupt another users mappings. |
|
*/ |
|
BUG_ON(in_interrupt()); |
|
|
|
/* From now on, migration cannot move the object */ |
|
pin_tag(handle); |
|
|
|
obj = handle_to_obj(handle); |
|
obj_to_location(obj, &page, &obj_idx); |
|
zspage = get_zspage(page); |
|
|
|
/* migration cannot move any subpage in this zspage */ |
|
migrate_read_lock(zspage); |
|
|
|
get_zspage_mapping(zspage, &class_idx, &fg); |
|
class = pool->size_class[class_idx]; |
|
off = (class->size * obj_idx) & ~PAGE_MASK; |
|
|
|
area = &get_cpu_var(zs_map_area); |
|
area->vm_mm = mm; |
|
if (off + class->size <= PAGE_SIZE) { |
|
/* this object is contained entirely within a page */ |
|
area->vm_addr = kmap_atomic(page); |
|
ret = area->vm_addr + off; |
|
goto out; |
|
} |
|
|
|
/* this object spans two pages */ |
|
pages[0] = page; |
|
pages[1] = get_next_page(page); |
|
BUG_ON(!pages[1]); |
|
|
|
ret = __zs_map_object(area, pages, off, class->size); |
|
out: |
|
if (likely(!PageHugeObject(page))) |
|
ret += ZS_HANDLE_SIZE; |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(zs_map_object); |
|
|
|
void zs_unmap_object(struct zs_pool *pool, unsigned long handle) |
|
{ |
|
struct zspage *zspage; |
|
struct page *page; |
|
unsigned long obj, off; |
|
unsigned int obj_idx; |
|
|
|
unsigned int class_idx; |
|
enum fullness_group fg; |
|
struct size_class *class; |
|
struct mapping_area *area; |
|
|
|
obj = handle_to_obj(handle); |
|
obj_to_location(obj, &page, &obj_idx); |
|
zspage = get_zspage(page); |
|
get_zspage_mapping(zspage, &class_idx, &fg); |
|
class = pool->size_class[class_idx]; |
|
off = (class->size * obj_idx) & ~PAGE_MASK; |
|
|
|
area = this_cpu_ptr(&zs_map_area); |
|
if (off + class->size <= PAGE_SIZE) |
|
kunmap_atomic(area->vm_addr); |
|
else { |
|
struct page *pages[2]; |
|
|
|
pages[0] = page; |
|
pages[1] = get_next_page(page); |
|
BUG_ON(!pages[1]); |
|
|
|
__zs_unmap_object(area, pages, off, class->size); |
|
} |
|
put_cpu_var(zs_map_area); |
|
|
|
migrate_read_unlock(zspage); |
|
unpin_tag(handle); |
|
} |
|
EXPORT_SYMBOL_GPL(zs_unmap_object); |
|
|
|
/** |
|
* zs_huge_class_size() - Returns the size (in bytes) of the first huge |
|
* zsmalloc &size_class. |
|
* @pool: zsmalloc pool to use |
|
* |
|
* The function returns the size of the first huge class - any object of equal |
|
* or bigger size will be stored in zspage consisting of a single physical |
|
* page. |
|
* |
|
* Context: Any context. |
|
* |
|
* Return: the size (in bytes) of the first huge zsmalloc &size_class. |
|
*/ |
|
size_t zs_huge_class_size(struct zs_pool *pool) |
|
{ |
|
return huge_class_size; |
|
} |
|
EXPORT_SYMBOL_GPL(zs_huge_class_size); |
|
|
|
static unsigned long obj_malloc(struct size_class *class, |
|
struct zspage *zspage, unsigned long handle) |
|
{ |
|
int i, nr_page, offset; |
|
unsigned long obj; |
|
struct link_free *link; |
|
|
|
struct page *m_page; |
|
unsigned long m_offset; |
|
void *vaddr; |
|
|
|
handle |= OBJ_ALLOCATED_TAG; |
|
obj = get_freeobj(zspage); |
|
|
|
offset = obj * class->size; |
|
nr_page = offset >> PAGE_SHIFT; |
|
m_offset = offset & ~PAGE_MASK; |
|
m_page = get_first_page(zspage); |
|
|
|
for (i = 0; i < nr_page; i++) |
|
m_page = get_next_page(m_page); |
|
|
|
vaddr = kmap_atomic(m_page); |
|
link = (struct link_free *)vaddr + m_offset / sizeof(*link); |
|
set_freeobj(zspage, link->next >> OBJ_TAG_BITS); |
|
if (likely(!PageHugeObject(m_page))) |
|
/* record handle in the header of allocated chunk */ |
|
link->handle = handle; |
|
else |
|
/* record handle to page->index */ |
|
zspage->first_page->index = handle; |
|
|
|
kunmap_atomic(vaddr); |
|
mod_zspage_inuse(zspage, 1); |
|
zs_stat_inc(class, OBJ_USED, 1); |
|
|
|
obj = location_to_obj(m_page, obj); |
|
|
|
return obj; |
|
} |
|
|
|
|
|
/** |
|
* zs_malloc - Allocate block of given size from pool. |
|
* @pool: pool to allocate from |
|
* @size: size of block to allocate |
|
* @gfp: gfp flags when allocating object |
|
* |
|
* On success, handle to the allocated object is returned, |
|
* otherwise 0. |
|
* Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail. |
|
*/ |
|
unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp) |
|
{ |
|
unsigned long handle, obj; |
|
struct size_class *class; |
|
enum fullness_group newfg; |
|
struct zspage *zspage; |
|
|
|
if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE)) |
|
return 0; |
|
|
|
handle = cache_alloc_handle(pool, gfp); |
|
if (!handle) |
|
return 0; |
|
|
|
/* extra space in chunk to keep the handle */ |
|
size += ZS_HANDLE_SIZE; |
|
class = pool->size_class[get_size_class_index(size)]; |
|
|
|
spin_lock(&class->lock); |
|
zspage = find_get_zspage(class); |
|
if (likely(zspage)) { |
|
obj = obj_malloc(class, zspage, handle); |
|
/* Now move the zspage to another fullness group, if required */ |
|
fix_fullness_group(class, zspage); |
|
record_obj(handle, obj); |
|
spin_unlock(&class->lock); |
|
|
|
return handle; |
|
} |
|
|
|
spin_unlock(&class->lock); |
|
|
|
zspage = alloc_zspage(pool, class, gfp); |
|
if (!zspage) { |
|
cache_free_handle(pool, handle); |
|
return 0; |
|
} |
|
|
|
spin_lock(&class->lock); |
|
obj = obj_malloc(class, zspage, handle); |
|
newfg = get_fullness_group(class, zspage); |
|
insert_zspage(class, zspage, newfg); |
|
set_zspage_mapping(zspage, class->index, newfg); |
|
record_obj(handle, obj); |
|
atomic_long_add(class->pages_per_zspage, |
|
&pool->pages_allocated); |
|
zs_stat_inc(class, OBJ_ALLOCATED, class->objs_per_zspage); |
|
|
|
/* We completely set up zspage so mark them as movable */ |
|
SetZsPageMovable(pool, zspage); |
|
spin_unlock(&class->lock); |
|
|
|
return handle; |
|
} |
|
EXPORT_SYMBOL_GPL(zs_malloc); |
|
|
|
static void obj_free(struct size_class *class, unsigned long obj) |
|
{ |
|
struct link_free *link; |
|
struct zspage *zspage; |
|
struct page *f_page; |
|
unsigned long f_offset; |
|
unsigned int f_objidx; |
|
void *vaddr; |
|
|
|
obj &= ~OBJ_ALLOCATED_TAG; |
|
obj_to_location(obj, &f_page, &f_objidx); |
|
f_offset = (class->size * f_objidx) & ~PAGE_MASK; |
|
zspage = get_zspage(f_page); |
|
|
|
vaddr = kmap_atomic(f_page); |
|
|
|
/* Insert this object in containing zspage's freelist */ |
|
link = (struct link_free *)(vaddr + f_offset); |
|
link->next = get_freeobj(zspage) << OBJ_TAG_BITS; |
|
kunmap_atomic(vaddr); |
|
set_freeobj(zspage, f_objidx); |
|
mod_zspage_inuse(zspage, -1); |
|
zs_stat_dec(class, OBJ_USED, 1); |
|
} |
|
|
|
void zs_free(struct zs_pool *pool, unsigned long handle) |
|
{ |
|
struct zspage *zspage; |
|
struct page *f_page; |
|
unsigned long obj; |
|
unsigned int f_objidx; |
|
int class_idx; |
|
struct size_class *class; |
|
enum fullness_group fullness; |
|
bool isolated; |
|
|
|
if (unlikely(!handle)) |
|
return; |
|
|
|
pin_tag(handle); |
|
obj = handle_to_obj(handle); |
|
obj_to_location(obj, &f_page, &f_objidx); |
|
zspage = get_zspage(f_page); |
|
|
|
migrate_read_lock(zspage); |
|
|
|
get_zspage_mapping(zspage, &class_idx, &fullness); |
|
class = pool->size_class[class_idx]; |
|
|
|
spin_lock(&class->lock); |
|
obj_free(class, obj); |
|
fullness = fix_fullness_group(class, zspage); |
|
if (fullness != ZS_EMPTY) { |
|
migrate_read_unlock(zspage); |
|
goto out; |
|
} |
|
|
|
isolated = is_zspage_isolated(zspage); |
|
migrate_read_unlock(zspage); |
|
/* If zspage is isolated, zs_page_putback will free the zspage */ |
|
if (likely(!isolated)) |
|
free_zspage(pool, class, zspage); |
|
out: |
|
|
|
spin_unlock(&class->lock); |
|
unpin_tag(handle); |
|
cache_free_handle(pool, handle); |
|
} |
|
EXPORT_SYMBOL_GPL(zs_free); |
|
|
|
static void zs_object_copy(struct size_class *class, unsigned long dst, |
|
unsigned long src) |
|
{ |
|
struct page *s_page, *d_page; |
|
unsigned int s_objidx, d_objidx; |
|
unsigned long s_off, d_off; |
|
void *s_addr, *d_addr; |
|
int s_size, d_size, size; |
|
int written = 0; |
|
|
|
s_size = d_size = class->size; |
|
|
|
obj_to_location(src, &s_page, &s_objidx); |
|
obj_to_location(dst, &d_page, &d_objidx); |
|
|
|
s_off = (class->size * s_objidx) & ~PAGE_MASK; |
|
d_off = (class->size * d_objidx) & ~PAGE_MASK; |
|
|
|
if (s_off + class->size > PAGE_SIZE) |
|
s_size = PAGE_SIZE - s_off; |
|
|
|
if (d_off + class->size > PAGE_SIZE) |
|
d_size = PAGE_SIZE - d_off; |
|
|
|
s_addr = kmap_atomic(s_page); |
|
d_addr = kmap_atomic(d_page); |
|
|
|
while (1) { |
|
size = min(s_size, d_size); |
|
memcpy(d_addr + d_off, s_addr + s_off, size); |
|
written += size; |
|
|
|
if (written == class->size) |
|
break; |
|
|
|
s_off += size; |
|
s_size -= size; |
|
d_off += size; |
|
d_size -= size; |
|
|
|
if (s_off >= PAGE_SIZE) { |
|
kunmap_atomic(d_addr); |
|
kunmap_atomic(s_addr); |
|
s_page = get_next_page(s_page); |
|
s_addr = kmap_atomic(s_page); |
|
d_addr = kmap_atomic(d_page); |
|
s_size = class->size - written; |
|
s_off = 0; |
|
} |
|
|
|
if (d_off >= PAGE_SIZE) { |
|
kunmap_atomic(d_addr); |
|
d_page = get_next_page(d_page); |
|
d_addr = kmap_atomic(d_page); |
|
d_size = class->size - written; |
|
d_off = 0; |
|
} |
|
} |
|
|
|
kunmap_atomic(d_addr); |
|
kunmap_atomic(s_addr); |
|
} |
|
|
|
/* |
|
* Find alloced object in zspage from index object and |
|
* return handle. |
|
*/ |
|
static unsigned long find_alloced_obj(struct size_class *class, |
|
struct page *page, int *obj_idx) |
|
{ |
|
unsigned long head; |
|
int offset = 0; |
|
int index = *obj_idx; |
|
unsigned long handle = 0; |
|
void *addr = kmap_atomic(page); |
|
|
|
offset = get_first_obj_offset(page); |
|
offset += class->size * index; |
|
|
|
while (offset < PAGE_SIZE) { |
|
head = obj_to_head(page, addr + offset); |
|
if (head & OBJ_ALLOCATED_TAG) { |
|
handle = head & ~OBJ_ALLOCATED_TAG; |
|
if (trypin_tag(handle)) |
|
break; |
|
handle = 0; |
|
} |
|
|
|
offset += class->size; |
|
index++; |
|
} |
|
|
|
kunmap_atomic(addr); |
|
|
|
*obj_idx = index; |
|
|
|
return handle; |
|
} |
|
|
|
struct zs_compact_control { |
|
/* Source spage for migration which could be a subpage of zspage */ |
|
struct page *s_page; |
|
/* Destination page for migration which should be a first page |
|
* of zspage. */ |
|
struct page *d_page; |
|
/* Starting object index within @s_page which used for live object |
|
* in the subpage. */ |
|
int obj_idx; |
|
}; |
|
|
|
static int migrate_zspage(struct zs_pool *pool, struct size_class *class, |
|
struct zs_compact_control *cc) |
|
{ |
|
unsigned long used_obj, free_obj; |
|
unsigned long handle; |
|
struct page *s_page = cc->s_page; |
|
struct page *d_page = cc->d_page; |
|
int obj_idx = cc->obj_idx; |
|
int ret = 0; |
|
|
|
while (1) { |
|
handle = find_alloced_obj(class, s_page, &obj_idx); |
|
if (!handle) { |
|
s_page = get_next_page(s_page); |
|
if (!s_page) |
|
break; |
|
obj_idx = 0; |
|
continue; |
|
} |
|
|
|
/* Stop if there is no more space */ |
|
if (zspage_full(class, get_zspage(d_page))) { |
|
unpin_tag(handle); |
|
ret = -ENOMEM; |
|
break; |
|
} |
|
|
|
used_obj = handle_to_obj(handle); |
|
free_obj = obj_malloc(class, get_zspage(d_page), handle); |
|
zs_object_copy(class, free_obj, used_obj); |
|
obj_idx++; |
|
/* |
|
* record_obj updates handle's value to free_obj and it will |
|
* invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which |
|
* breaks synchronization using pin_tag(e,g, zs_free) so |
|
* let's keep the lock bit. |
|
*/ |
|
free_obj |= BIT(HANDLE_PIN_BIT); |
|
record_obj(handle, free_obj); |
|
unpin_tag(handle); |
|
obj_free(class, used_obj); |
|
} |
|
|
|
/* Remember last position in this iteration */ |
|
cc->s_page = s_page; |
|
cc->obj_idx = obj_idx; |
|
|
|
return ret; |
|
} |
|
|
|
static struct zspage *isolate_zspage(struct size_class *class, bool source) |
|
{ |
|
int i; |
|
struct zspage *zspage; |
|
enum fullness_group fg[2] = {ZS_ALMOST_EMPTY, ZS_ALMOST_FULL}; |
|
|
|
if (!source) { |
|
fg[0] = ZS_ALMOST_FULL; |
|
fg[1] = ZS_ALMOST_EMPTY; |
|
} |
|
|
|
for (i = 0; i < 2; i++) { |
|
zspage = list_first_entry_or_null(&class->fullness_list[fg[i]], |
|
struct zspage, list); |
|
if (zspage) { |
|
VM_BUG_ON(is_zspage_isolated(zspage)); |
|
remove_zspage(class, zspage, fg[i]); |
|
return zspage; |
|
} |
|
} |
|
|
|
return zspage; |
|
} |
|
|
|
/* |
|
* putback_zspage - add @zspage into right class's fullness list |
|
* @class: destination class |
|
* @zspage: target page |
|
* |
|
* Return @zspage's fullness_group |
|
*/ |
|
static enum fullness_group putback_zspage(struct size_class *class, |
|
struct zspage *zspage) |
|
{ |
|
enum fullness_group fullness; |
|
|
|
VM_BUG_ON(is_zspage_isolated(zspage)); |
|
|
|
fullness = get_fullness_group(class, zspage); |
|
insert_zspage(class, zspage, fullness); |
|
set_zspage_mapping(zspage, class->index, fullness); |
|
|
|
return fullness; |
|
} |
|
|
|
#ifdef CONFIG_COMPACTION |
|
/* |
|
* To prevent zspage destroy during migration, zspage freeing should |
|
* hold locks of all pages in the zspage. |
|
*/ |
|
static void lock_zspage(struct zspage *zspage) |
|
{ |
|
struct page *page = get_first_page(zspage); |
|
|
|
do { |
|
lock_page(page); |
|
} while ((page = get_next_page(page)) != NULL); |
|
} |
|
|
|
static int zs_init_fs_context(struct fs_context *fc) |
|
{ |
|
return init_pseudo(fc, ZSMALLOC_MAGIC) ? 0 : -ENOMEM; |
|
} |
|
|
|
static struct file_system_type zsmalloc_fs = { |
|
.name = "zsmalloc", |
|
.init_fs_context = zs_init_fs_context, |
|
.kill_sb = kill_anon_super, |
|
}; |
|
|
|
static int zsmalloc_mount(void) |
|
{ |
|
int ret = 0; |
|
|
|
zsmalloc_mnt = kern_mount(&zsmalloc_fs); |
|
if (IS_ERR(zsmalloc_mnt)) |
|
ret = PTR_ERR(zsmalloc_mnt); |
|
|
|
return ret; |
|
} |
|
|
|
static void zsmalloc_unmount(void) |
|
{ |
|
kern_unmount(zsmalloc_mnt); |
|
} |
|
|
|
static void migrate_lock_init(struct zspage *zspage) |
|
{ |
|
rwlock_init(&zspage->lock); |
|
} |
|
|
|
static void migrate_read_lock(struct zspage *zspage) __acquires(&zspage->lock) |
|
{ |
|
read_lock(&zspage->lock); |
|
} |
|
|
|
static void migrate_read_unlock(struct zspage *zspage) __releases(&zspage->lock) |
|
{ |
|
read_unlock(&zspage->lock); |
|
} |
|
|
|
static void migrate_write_lock(struct zspage *zspage) |
|
{ |
|
write_lock(&zspage->lock); |
|
} |
|
|
|
static void migrate_write_unlock(struct zspage *zspage) |
|
{ |
|
write_unlock(&zspage->lock); |
|
} |
|
|
|
/* Number of isolated subpage for *page migration* in this zspage */ |
|
static void inc_zspage_isolation(struct zspage *zspage) |
|
{ |
|
zspage->isolated++; |
|
} |
|
|
|
static void dec_zspage_isolation(struct zspage *zspage) |
|
{ |
|
zspage->isolated--; |
|
} |
|
|
|
static void putback_zspage_deferred(struct zs_pool *pool, |
|
struct size_class *class, |
|
struct zspage *zspage) |
|
{ |
|
enum fullness_group fg; |
|
|
|
fg = putback_zspage(class, zspage); |
|
if (fg == ZS_EMPTY) |
|
schedule_work(&pool->free_work); |
|
|
|
} |
|
|
|
static inline void zs_pool_dec_isolated(struct zs_pool *pool) |
|
{ |
|
VM_BUG_ON(atomic_long_read(&pool->isolated_pages) <= 0); |
|
atomic_long_dec(&pool->isolated_pages); |
|
/* |
|
* There's no possibility of racing, since wait_for_isolated_drain() |
|
* checks the isolated count under &class->lock after enqueuing |
|
* on migration_wait. |
|
*/ |
|
if (atomic_long_read(&pool->isolated_pages) == 0 && pool->destroying) |
|
wake_up_all(&pool->migration_wait); |
|
} |
|
|
|
static void replace_sub_page(struct size_class *class, struct zspage *zspage, |
|
struct page *newpage, struct page *oldpage) |
|
{ |
|
struct page *page; |
|
struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE] = {NULL, }; |
|
int idx = 0; |
|
|
|
page = get_first_page(zspage); |
|
do { |
|
if (page == oldpage) |
|
pages[idx] = newpage; |
|
else |
|
pages[idx] = page; |
|
idx++; |
|
} while ((page = get_next_page(page)) != NULL); |
|
|
|
create_page_chain(class, zspage, pages); |
|
set_first_obj_offset(newpage, get_first_obj_offset(oldpage)); |
|
if (unlikely(PageHugeObject(oldpage))) |
|
newpage->index = oldpage->index; |
|
__SetPageMovable(newpage, page_mapping(oldpage)); |
|
} |
|
|
|
static bool zs_page_isolate(struct page *page, isolate_mode_t mode) |
|
{ |
|
struct zs_pool *pool; |
|
struct size_class *class; |
|
int class_idx; |
|
enum fullness_group fullness; |
|
struct zspage *zspage; |
|
struct address_space *mapping; |
|
|
|
/* |
|
* Page is locked so zspage couldn't be destroyed. For detail, look at |
|
* lock_zspage in free_zspage. |
|
*/ |
|
VM_BUG_ON_PAGE(!PageMovable(page), page); |
|
VM_BUG_ON_PAGE(PageIsolated(page), page); |
|
|
|
zspage = get_zspage(page); |
|
|
|
/* |
|
* Without class lock, fullness could be stale while class_idx is okay |
|
* because class_idx is constant unless page is freed so we should get |
|
* fullness again under class lock. |
|
*/ |
|
get_zspage_mapping(zspage, &class_idx, &fullness); |
|
mapping = page_mapping(page); |
|
pool = mapping->private_data; |
|
class = pool->size_class[class_idx]; |
|
|
|
spin_lock(&class->lock); |
|
if (get_zspage_inuse(zspage) == 0) { |
|
spin_unlock(&class->lock); |
|
return false; |
|
} |
|
|
|
/* zspage is isolated for object migration */ |
|
if (list_empty(&zspage->list) && !is_zspage_isolated(zspage)) { |
|
spin_unlock(&class->lock); |
|
return false; |
|
} |
|
|
|
/* |
|
* If this is first time isolation for the zspage, isolate zspage from |
|
* size_class to prevent further object allocation from the zspage. |
|
*/ |
|
if (!list_empty(&zspage->list) && !is_zspage_isolated(zspage)) { |
|
get_zspage_mapping(zspage, &class_idx, &fullness); |
|
atomic_long_inc(&pool->isolated_pages); |
|
remove_zspage(class, zspage, fullness); |
|
} |
|
|
|
inc_zspage_isolation(zspage); |
|
spin_unlock(&class->lock); |
|
|
|
return true; |
|
} |
|
|
|
static int zs_page_migrate(struct address_space *mapping, struct page *newpage, |
|
struct page *page, enum migrate_mode mode) |
|
{ |
|
struct zs_pool *pool; |
|
struct size_class *class; |
|
int class_idx; |
|
enum fullness_group fullness; |
|
struct zspage *zspage; |
|
struct page *dummy; |
|
void *s_addr, *d_addr, *addr; |
|
int offset, pos; |
|
unsigned long handle, head; |
|
unsigned long old_obj, new_obj; |
|
unsigned int obj_idx; |
|
int ret = -EAGAIN; |
|
|
|
/* |
|
* We cannot support the _NO_COPY case here, because copy needs to |
|
* happen under the zs lock, which does not work with |
|
* MIGRATE_SYNC_NO_COPY workflow. |
|
*/ |
|
if (mode == MIGRATE_SYNC_NO_COPY) |
|
return -EINVAL; |
|
|
|
VM_BUG_ON_PAGE(!PageMovable(page), page); |
|
VM_BUG_ON_PAGE(!PageIsolated(page), page); |
|
|
|
zspage = get_zspage(page); |
|
|
|
/* Concurrent compactor cannot migrate any subpage in zspage */ |
|
migrate_write_lock(zspage); |
|
get_zspage_mapping(zspage, &class_idx, &fullness); |
|
pool = mapping->private_data; |
|
class = pool->size_class[class_idx]; |
|
offset = get_first_obj_offset(page); |
|
|
|
spin_lock(&class->lock); |
|
if (!get_zspage_inuse(zspage)) { |
|
/* |
|
* Set "offset" to end of the page so that every loops |
|
* skips unnecessary object scanning. |
|
*/ |
|
offset = PAGE_SIZE; |
|
} |
|
|
|
pos = offset; |
|
s_addr = kmap_atomic(page); |
|
while (pos < PAGE_SIZE) { |
|
head = obj_to_head(page, s_addr + pos); |
|
if (head & OBJ_ALLOCATED_TAG) { |
|
handle = head & ~OBJ_ALLOCATED_TAG; |
|
if (!trypin_tag(handle)) |
|
goto unpin_objects; |
|
} |
|
pos += class->size; |
|
} |
|
|
|
/* |
|
* Here, any user cannot access all objects in the zspage so let's move. |
|
*/ |
|
d_addr = kmap_atomic(newpage); |
|
memcpy(d_addr, s_addr, PAGE_SIZE); |
|
kunmap_atomic(d_addr); |
|
|
|
for (addr = s_addr + offset; addr < s_addr + pos; |
|
addr += class->size) { |
|
head = obj_to_head(page, addr); |
|
if (head & OBJ_ALLOCATED_TAG) { |
|
handle = head & ~OBJ_ALLOCATED_TAG; |
|
if (!testpin_tag(handle)) |
|
BUG(); |
|
|
|
old_obj = handle_to_obj(handle); |
|
obj_to_location(old_obj, &dummy, &obj_idx); |
|
new_obj = (unsigned long)location_to_obj(newpage, |
|
obj_idx); |
|
new_obj |= BIT(HANDLE_PIN_BIT); |
|
record_obj(handle, new_obj); |
|
} |
|
} |
|
|
|
replace_sub_page(class, zspage, newpage, page); |
|
get_page(newpage); |
|
|
|
dec_zspage_isolation(zspage); |
|
|
|
/* |
|
* Page migration is done so let's putback isolated zspage to |
|
* the list if @page is final isolated subpage in the zspage. |
|
*/ |
|
if (!is_zspage_isolated(zspage)) { |
|
/* |
|
* We cannot race with zs_destroy_pool() here because we wait |
|
* for isolation to hit zero before we start destroying. |
|
* Also, we ensure that everyone can see pool->destroying before |
|
* we start waiting. |
|
*/ |
|
putback_zspage_deferred(pool, class, zspage); |
|
zs_pool_dec_isolated(pool); |
|
} |
|
|
|
if (page_zone(newpage) != page_zone(page)) { |
|
dec_zone_page_state(page, NR_ZSPAGES); |
|
inc_zone_page_state(newpage, NR_ZSPAGES); |
|
} |
|
|
|
reset_page(page); |
|
put_page(page); |
|
page = newpage; |
|
|
|
ret = MIGRATEPAGE_SUCCESS; |
|
unpin_objects: |
|
for (addr = s_addr + offset; addr < s_addr + pos; |
|
addr += class->size) { |
|
head = obj_to_head(page, addr); |
|
if (head & OBJ_ALLOCATED_TAG) { |
|
handle = head & ~OBJ_ALLOCATED_TAG; |
|
if (!testpin_tag(handle)) |
|
BUG(); |
|
unpin_tag(handle); |
|
} |
|
} |
|
kunmap_atomic(s_addr); |
|
spin_unlock(&class->lock); |
|
migrate_write_unlock(zspage); |
|
|
|
return ret; |
|
} |
|
|
|
static void zs_page_putback(struct page *page) |
|
{ |
|
struct zs_pool *pool; |
|
struct size_class *class; |
|
int class_idx; |
|
enum fullness_group fg; |
|
struct address_space *mapping; |
|
struct zspage *zspage; |
|
|
|
VM_BUG_ON_PAGE(!PageMovable(page), page); |
|
VM_BUG_ON_PAGE(!PageIsolated(page), page); |
|
|
|
zspage = get_zspage(page); |
|
get_zspage_mapping(zspage, &class_idx, &fg); |
|
mapping = page_mapping(page); |
|
pool = mapping->private_data; |
|
class = pool->size_class[class_idx]; |
|
|
|
spin_lock(&class->lock); |
|
dec_zspage_isolation(zspage); |
|
if (!is_zspage_isolated(zspage)) { |
|
/* |
|
* Due to page_lock, we cannot free zspage immediately |
|
* so let's defer. |
|
*/ |
|
putback_zspage_deferred(pool, class, zspage); |
|
zs_pool_dec_isolated(pool); |
|
} |
|
spin_unlock(&class->lock); |
|
} |
|
|
|
static const struct address_space_operations zsmalloc_aops = { |
|
.isolate_page = zs_page_isolate, |
|
.migratepage = zs_page_migrate, |
|
.putback_page = zs_page_putback, |
|
}; |
|
|
|
static int zs_register_migration(struct zs_pool *pool) |
|
{ |
|
pool->inode = alloc_anon_inode(zsmalloc_mnt->mnt_sb); |
|
if (IS_ERR(pool->inode)) { |
|
pool->inode = NULL; |
|
return 1; |
|
} |
|
|
|
pool->inode->i_mapping->private_data = pool; |
|
pool->inode->i_mapping->a_ops = &zsmalloc_aops; |
|
return 0; |
|
} |
|
|
|
static bool pool_isolated_are_drained(struct zs_pool *pool) |
|
{ |
|
return atomic_long_read(&pool->isolated_pages) == 0; |
|
} |
|
|
|
/* Function for resolving migration */ |
|
static void wait_for_isolated_drain(struct zs_pool *pool) |
|
{ |
|
|
|
/* |
|
* We're in the process of destroying the pool, so there are no |
|
* active allocations. zs_page_isolate() fails for completely free |
|
* zspages, so we need only wait for the zs_pool's isolated |
|
* count to hit zero. |
|
*/ |
|
wait_event(pool->migration_wait, |
|
pool_isolated_are_drained(pool)); |
|
} |
|
|
|
static void zs_unregister_migration(struct zs_pool *pool) |
|
{ |
|
pool->destroying = true; |
|
/* |
|
* We need a memory barrier here to ensure global visibility of |
|
* pool->destroying. Thus pool->isolated pages will either be 0 in which |
|
* case we don't care, or it will be > 0 and pool->destroying will |
|
* ensure that we wake up once isolation hits 0. |
|
*/ |
|
smp_mb(); |
|
wait_for_isolated_drain(pool); /* This can block */ |
|
flush_work(&pool->free_work); |
|
iput(pool->inode); |
|
} |
|
|
|
/* |
|
* Caller should hold page_lock of all pages in the zspage |
|
* In here, we cannot use zspage meta data. |
|
*/ |
|
static void async_free_zspage(struct work_struct *work) |
|
{ |
|
int i; |
|
struct size_class *class; |
|
unsigned int class_idx; |
|
enum fullness_group fullness; |
|
struct zspage *zspage, *tmp; |
|
LIST_HEAD(free_pages); |
|
struct zs_pool *pool = container_of(work, struct zs_pool, |
|
free_work); |
|
|
|
for (i = 0; i < ZS_SIZE_CLASSES; i++) { |
|
class = pool->size_class[i]; |
|
if (class->index != i) |
|
continue; |
|
|
|
spin_lock(&class->lock); |
|
list_splice_init(&class->fullness_list[ZS_EMPTY], &free_pages); |
|
spin_unlock(&class->lock); |
|
} |
|
|
|
|
|
list_for_each_entry_safe(zspage, tmp, &free_pages, list) { |
|
list_del(&zspage->list); |
|
lock_zspage(zspage); |
|
|
|
get_zspage_mapping(zspage, &class_idx, &fullness); |
|
VM_BUG_ON(fullness != ZS_EMPTY); |
|
class = pool->size_class[class_idx]; |
|
spin_lock(&class->lock); |
|
__free_zspage(pool, pool->size_class[class_idx], zspage); |
|
spin_unlock(&class->lock); |
|
} |
|
}; |
|
|
|
static void kick_deferred_free(struct zs_pool *pool) |
|
{ |
|
schedule_work(&pool->free_work); |
|
} |
|
|
|
static void init_deferred_free(struct zs_pool *pool) |
|
{ |
|
INIT_WORK(&pool->free_work, async_free_zspage); |
|
} |
|
|
|
static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) |
|
{ |
|
struct page *page = get_first_page(zspage); |
|
|
|
do { |
|
WARN_ON(!trylock_page(page)); |
|
__SetPageMovable(page, pool->inode->i_mapping); |
|
unlock_page(page); |
|
} while ((page = get_next_page(page)) != NULL); |
|
} |
|
#endif |
|
|
|
/* |
|
* |
|
* Based on the number of unused allocated objects calculate |
|
* and return the number of pages that we can free. |
|
*/ |
|
static unsigned long zs_can_compact(struct size_class *class) |
|
{ |
|
unsigned long obj_wasted; |
|
unsigned long obj_allocated = zs_stat_get(class, OBJ_ALLOCATED); |
|
unsigned long obj_used = zs_stat_get(class, OBJ_USED); |
|
|
|
if (obj_allocated <= obj_used) |
|
return 0; |
|
|
|
obj_wasted = obj_allocated - obj_used; |
|
obj_wasted /= class->objs_per_zspage; |
|
|
|
return obj_wasted * class->pages_per_zspage; |
|
} |
|
|
|
static unsigned long __zs_compact(struct zs_pool *pool, |
|
struct size_class *class) |
|
{ |
|
struct zs_compact_control cc; |
|
struct zspage *src_zspage; |
|
struct zspage *dst_zspage = NULL; |
|
unsigned long pages_freed = 0; |
|
|
|
spin_lock(&class->lock); |
|
while ((src_zspage = isolate_zspage(class, true))) { |
|
|
|
if (!zs_can_compact(class)) |
|
break; |
|
|
|
cc.obj_idx = 0; |
|
cc.s_page = get_first_page(src_zspage); |
|
|
|
while ((dst_zspage = isolate_zspage(class, false))) { |
|
cc.d_page = get_first_page(dst_zspage); |
|
/* |
|
* If there is no more space in dst_page, resched |
|
* and see if anyone had allocated another zspage. |
|
*/ |
|
if (!migrate_zspage(pool, class, &cc)) |
|
break; |
|
|
|
putback_zspage(class, dst_zspage); |
|
} |
|
|
|
/* Stop if we couldn't find slot */ |
|
if (dst_zspage == NULL) |
|
break; |
|
|
|
putback_zspage(class, dst_zspage); |
|
if (putback_zspage(class, src_zspage) == ZS_EMPTY) { |
|
free_zspage(pool, class, src_zspage); |
|
pages_freed += class->pages_per_zspage; |
|
} |
|
spin_unlock(&class->lock); |
|
cond_resched(); |
|
spin_lock(&class->lock); |
|
} |
|
|
|
if (src_zspage) |
|
putback_zspage(class, src_zspage); |
|
|
|
spin_unlock(&class->lock); |
|
|
|
return pages_freed; |
|
} |
|
|
|
unsigned long zs_compact(struct zs_pool *pool) |
|
{ |
|
int i; |
|
struct size_class *class; |
|
unsigned long pages_freed = 0; |
|
|
|
for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { |
|
class = pool->size_class[i]; |
|
if (!class) |
|
continue; |
|
if (class->index != i) |
|
continue; |
|
pages_freed += __zs_compact(pool, class); |
|
} |
|
atomic_long_add(pages_freed, &pool->stats.pages_compacted); |
|
|
|
return pages_freed; |
|
} |
|
EXPORT_SYMBOL_GPL(zs_compact); |
|
|
|
void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats) |
|
{ |
|
memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats)); |
|
} |
|
EXPORT_SYMBOL_GPL(zs_pool_stats); |
|
|
|
static unsigned long zs_shrinker_scan(struct shrinker *shrinker, |
|
struct shrink_control *sc) |
|
{ |
|
unsigned long pages_freed; |
|
struct zs_pool *pool = container_of(shrinker, struct zs_pool, |
|
shrinker); |
|
|
|
/* |
|
* Compact classes and calculate compaction delta. |
|
* Can run concurrently with a manually triggered |
|
* (by user) compaction. |
|
*/ |
|
pages_freed = zs_compact(pool); |
|
|
|
return pages_freed ? pages_freed : SHRINK_STOP; |
|
} |
|
|
|
static unsigned long zs_shrinker_count(struct shrinker *shrinker, |
|
struct shrink_control *sc) |
|
{ |
|
int i; |
|
struct size_class *class; |
|
unsigned long pages_to_free = 0; |
|
struct zs_pool *pool = container_of(shrinker, struct zs_pool, |
|
shrinker); |
|
|
|
for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { |
|
class = pool->size_class[i]; |
|
if (!class) |
|
continue; |
|
if (class->index != i) |
|
continue; |
|
|
|
pages_to_free += zs_can_compact(class); |
|
} |
|
|
|
return pages_to_free; |
|
} |
|
|
|
static void zs_unregister_shrinker(struct zs_pool *pool) |
|
{ |
|
unregister_shrinker(&pool->shrinker); |
|
} |
|
|
|
static int zs_register_shrinker(struct zs_pool *pool) |
|
{ |
|
pool->shrinker.scan_objects = zs_shrinker_scan; |
|
pool->shrinker.count_objects = zs_shrinker_count; |
|
pool->shrinker.batch = 0; |
|
pool->shrinker.seeks = DEFAULT_SEEKS; |
|
|
|
return register_shrinker(&pool->shrinker); |
|
} |
|
|
|
/** |
|
* zs_create_pool - Creates an allocation pool to work from. |
|
* @name: pool name to be created |
|
* |
|
* This function must be called before anything when using |
|
* the zsmalloc allocator. |
|
* |
|
* On success, a pointer to the newly created pool is returned, |
|
* otherwise NULL. |
|
*/ |
|
struct zs_pool *zs_create_pool(const char *name) |
|
{ |
|
int i; |
|
struct zs_pool *pool; |
|
struct size_class *prev_class = NULL; |
|
|
|
pool = kzalloc(sizeof(*pool), GFP_KERNEL); |
|
if (!pool) |
|
return NULL; |
|
|
|
init_deferred_free(pool); |
|
|
|
pool->name = kstrdup(name, GFP_KERNEL); |
|
if (!pool->name) |
|
goto err; |
|
|
|
#ifdef CONFIG_COMPACTION |
|
init_waitqueue_head(&pool->migration_wait); |
|
#endif |
|
|
|
if (create_cache(pool)) |
|
goto err; |
|
|
|
/* |
|
* Iterate reversely, because, size of size_class that we want to use |
|
* for merging should be larger or equal to current size. |
|
*/ |
|
for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) { |
|
int size; |
|
int pages_per_zspage; |
|
int objs_per_zspage; |
|
struct size_class *class; |
|
int fullness = 0; |
|
|
|
size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA; |
|
if (size > ZS_MAX_ALLOC_SIZE) |
|
size = ZS_MAX_ALLOC_SIZE; |
|
pages_per_zspage = get_pages_per_zspage(size); |
|
objs_per_zspage = pages_per_zspage * PAGE_SIZE / size; |
|
|
|
/* |
|
* We iterate from biggest down to smallest classes, |
|
* so huge_class_size holds the size of the first huge |
|
* class. Any object bigger than or equal to that will |
|
* endup in the huge class. |
|
*/ |
|
if (pages_per_zspage != 1 && objs_per_zspage != 1 && |
|
!huge_class_size) { |
|
huge_class_size = size; |
|
/* |
|
* The object uses ZS_HANDLE_SIZE bytes to store the |
|
* handle. We need to subtract it, because zs_malloc() |
|
* unconditionally adds handle size before it performs |
|
* size class search - so object may be smaller than |
|
* huge class size, yet it still can end up in the huge |
|
* class because it grows by ZS_HANDLE_SIZE extra bytes |
|
* right before class lookup. |
|
*/ |
|
huge_class_size -= (ZS_HANDLE_SIZE - 1); |
|
} |
|
|
|
/* |
|
* size_class is used for normal zsmalloc operation such |
|
* as alloc/free for that size. Although it is natural that we |
|
* have one size_class for each size, there is a chance that we |
|
* can get more memory utilization if we use one size_class for |
|
* many different sizes whose size_class have same |
|
* characteristics. So, we makes size_class point to |
|
* previous size_class if possible. |
|
*/ |
|
if (prev_class) { |
|
if (can_merge(prev_class, pages_per_zspage, objs_per_zspage)) { |
|
pool->size_class[i] = prev_class; |
|
continue; |
|
} |
|
} |
|
|
|
class = kzalloc(sizeof(struct size_class), GFP_KERNEL); |
|
if (!class) |
|
goto err; |
|
|
|
class->size = size; |
|
class->index = i; |
|
class->pages_per_zspage = pages_per_zspage; |
|
class->objs_per_zspage = objs_per_zspage; |
|
spin_lock_init(&class->lock); |
|
pool->size_class[i] = class; |
|
for (fullness = ZS_EMPTY; fullness < NR_ZS_FULLNESS; |
|
fullness++) |
|
INIT_LIST_HEAD(&class->fullness_list[fullness]); |
|
|
|
prev_class = class; |
|
} |
|
|
|
/* debug only, don't abort if it fails */ |
|
zs_pool_stat_create(pool, name); |
|
|
|
if (zs_register_migration(pool)) |
|
goto err; |
|
|
|
/* |
|
* Not critical since shrinker is only used to trigger internal |
|
* defragmentation of the pool which is pretty optional thing. If |
|
* registration fails we still can use the pool normally and user can |
|
* trigger compaction manually. Thus, ignore return code. |
|
*/ |
|
zs_register_shrinker(pool); |
|
|
|
return pool; |
|
|
|
err: |
|
zs_destroy_pool(pool); |
|
return NULL; |
|
} |
|
EXPORT_SYMBOL_GPL(zs_create_pool); |
|
|
|
void zs_destroy_pool(struct zs_pool *pool) |
|
{ |
|
int i; |
|
|
|
zs_unregister_shrinker(pool); |
|
zs_unregister_migration(pool); |
|
zs_pool_stat_destroy(pool); |
|
|
|
for (i = 0; i < ZS_SIZE_CLASSES; i++) { |
|
int fg; |
|
struct size_class *class = pool->size_class[i]; |
|
|
|
if (!class) |
|
continue; |
|
|
|
if (class->index != i) |
|
continue; |
|
|
|
for (fg = ZS_EMPTY; fg < NR_ZS_FULLNESS; fg++) { |
|
if (!list_empty(&class->fullness_list[fg])) { |
|
pr_info("Freeing non-empty class with size %db, fullness group %d\n", |
|
class->size, fg); |
|
} |
|
} |
|
kfree(class); |
|
} |
|
|
|
destroy_cache(pool); |
|
kfree(pool->name); |
|
kfree(pool); |
|
} |
|
EXPORT_SYMBOL_GPL(zs_destroy_pool); |
|
|
|
static int __init zs_init(void) |
|
{ |
|
int ret; |
|
|
|
ret = zsmalloc_mount(); |
|
if (ret) |
|
goto out; |
|
|
|
ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare", |
|
zs_cpu_prepare, zs_cpu_dead); |
|
if (ret) |
|
goto hp_setup_fail; |
|
|
|
#ifdef CONFIG_ZPOOL |
|
zpool_register_driver(&zs_zpool_driver); |
|
#endif |
|
|
|
zs_stat_init(); |
|
|
|
return 0; |
|
|
|
hp_setup_fail: |
|
zsmalloc_unmount(); |
|
out: |
|
return ret; |
|
} |
|
|
|
static void __exit zs_exit(void) |
|
{ |
|
#ifdef CONFIG_ZPOOL |
|
zpool_unregister_driver(&zs_zpool_driver); |
|
#endif |
|
zsmalloc_unmount(); |
|
cpuhp_remove_state(CPUHP_MM_ZS_PREPARE); |
|
|
|
zs_stat_exit(); |
|
} |
|
|
|
module_init(zs_init); |
|
module_exit(zs_exit); |
|
|
|
MODULE_LICENSE("Dual BSD/GPL"); |
|
MODULE_AUTHOR("Nitin Gupta <[email protected]>");
|
|
|