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1998 lines
56 KiB
1998 lines
56 KiB
/* |
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* mm/rmap.c - physical to virtual reverse mappings |
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* |
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* Copyright 2001, Rik van Riel <[email protected]> |
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* Released under the General Public License (GPL). |
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* |
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* Simple, low overhead reverse mapping scheme. |
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* Please try to keep this thing as modular as possible. |
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* |
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* Provides methods for unmapping each kind of mapped page: |
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* the anon methods track anonymous pages, and |
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* the file methods track pages belonging to an inode. |
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* |
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* Original design by Rik van Riel <[email protected]> 2001 |
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* File methods by Dave McCracken <[email protected]> 2003, 2004 |
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* Anonymous methods by Andrea Arcangeli <[email protected]> 2004 |
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* Contributions by Hugh Dickins 2003, 2004 |
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*/ |
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|
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/* |
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* Lock ordering in mm: |
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* |
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* inode->i_mutex (while writing or truncating, not reading or faulting) |
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* mm->mmap_lock |
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* page->flags PG_locked (lock_page) * (see huegtlbfs below) |
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* hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share) |
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* mapping->i_mmap_rwsem |
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* hugetlb_fault_mutex (hugetlbfs specific page fault mutex) |
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* anon_vma->rwsem |
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* mm->page_table_lock or pte_lock |
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* swap_lock (in swap_duplicate, swap_info_get) |
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* mmlist_lock (in mmput, drain_mmlist and others) |
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* mapping->private_lock (in __set_page_dirty_buffers) |
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* lock_page_memcg move_lock (in __set_page_dirty_buffers) |
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* i_pages lock (widely used) |
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* lruvec->lru_lock (in lock_page_lruvec_irq) |
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* inode->i_lock (in set_page_dirty's __mark_inode_dirty) |
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* bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) |
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* sb_lock (within inode_lock in fs/fs-writeback.c) |
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* i_pages lock (widely used, in set_page_dirty, |
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* in arch-dependent flush_dcache_mmap_lock, |
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* within bdi.wb->list_lock in __sync_single_inode) |
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* |
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* anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon) |
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* ->tasklist_lock |
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* pte map lock |
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* |
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* * hugetlbfs PageHuge() pages take locks in this order: |
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* mapping->i_mmap_rwsem |
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* hugetlb_fault_mutex (hugetlbfs specific page fault mutex) |
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* page->flags PG_locked (lock_page) |
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*/ |
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|
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#include <linux/mm.h> |
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#include <linux/sched/mm.h> |
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#include <linux/sched/task.h> |
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#include <linux/pagemap.h> |
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#include <linux/swap.h> |
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#include <linux/swapops.h> |
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#include <linux/slab.h> |
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#include <linux/init.h> |
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#include <linux/ksm.h> |
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#include <linux/rmap.h> |
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#include <linux/rcupdate.h> |
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#include <linux/export.h> |
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#include <linux/memcontrol.h> |
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#include <linux/mmu_notifier.h> |
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#include <linux/migrate.h> |
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#include <linux/hugetlb.h> |
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#include <linux/huge_mm.h> |
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#include <linux/backing-dev.h> |
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#include <linux/page_idle.h> |
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#include <linux/memremap.h> |
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#include <linux/userfaultfd_k.h> |
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|
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#include <asm/tlbflush.h> |
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#include <trace/events/tlb.h> |
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#include "internal.h" |
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static struct kmem_cache *anon_vma_cachep; |
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static struct kmem_cache *anon_vma_chain_cachep; |
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|
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static inline struct anon_vma *anon_vma_alloc(void) |
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{ |
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struct anon_vma *anon_vma; |
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anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); |
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if (anon_vma) { |
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atomic_set(&anon_vma->refcount, 1); |
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anon_vma->degree = 1; /* Reference for first vma */ |
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anon_vma->parent = anon_vma; |
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/* |
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* Initialise the anon_vma root to point to itself. If called |
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* from fork, the root will be reset to the parents anon_vma. |
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*/ |
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anon_vma->root = anon_vma; |
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} |
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|
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return anon_vma; |
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} |
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static inline void anon_vma_free(struct anon_vma *anon_vma) |
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{ |
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VM_BUG_ON(atomic_read(&anon_vma->refcount)); |
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|
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/* |
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* Synchronize against page_lock_anon_vma_read() such that |
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* we can safely hold the lock without the anon_vma getting |
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* freed. |
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* |
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* Relies on the full mb implied by the atomic_dec_and_test() from |
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* put_anon_vma() against the acquire barrier implied by |
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* down_read_trylock() from page_lock_anon_vma_read(). This orders: |
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* |
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* page_lock_anon_vma_read() VS put_anon_vma() |
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* down_read_trylock() atomic_dec_and_test() |
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* LOCK MB |
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* atomic_read() rwsem_is_locked() |
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* |
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* LOCK should suffice since the actual taking of the lock must |
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* happen _before_ what follows. |
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*/ |
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might_sleep(); |
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if (rwsem_is_locked(&anon_vma->root->rwsem)) { |
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anon_vma_lock_write(anon_vma); |
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anon_vma_unlock_write(anon_vma); |
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} |
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kmem_cache_free(anon_vma_cachep, anon_vma); |
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} |
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static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp) |
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{ |
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return kmem_cache_alloc(anon_vma_chain_cachep, gfp); |
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} |
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static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) |
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{ |
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kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); |
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} |
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static void anon_vma_chain_link(struct vm_area_struct *vma, |
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struct anon_vma_chain *avc, |
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struct anon_vma *anon_vma) |
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{ |
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avc->vma = vma; |
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avc->anon_vma = anon_vma; |
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list_add(&avc->same_vma, &vma->anon_vma_chain); |
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anon_vma_interval_tree_insert(avc, &anon_vma->rb_root); |
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} |
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|
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/** |
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* __anon_vma_prepare - attach an anon_vma to a memory region |
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* @vma: the memory region in question |
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* |
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* This makes sure the memory mapping described by 'vma' has |
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* an 'anon_vma' attached to it, so that we can associate the |
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* anonymous pages mapped into it with that anon_vma. |
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* |
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* The common case will be that we already have one, which |
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* is handled inline by anon_vma_prepare(). But if |
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* not we either need to find an adjacent mapping that we |
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* can re-use the anon_vma from (very common when the only |
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* reason for splitting a vma has been mprotect()), or we |
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* allocate a new one. |
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* |
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* Anon-vma allocations are very subtle, because we may have |
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* optimistically looked up an anon_vma in page_lock_anon_vma_read() |
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* and that may actually touch the rwsem even in the newly |
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* allocated vma (it depends on RCU to make sure that the |
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* anon_vma isn't actually destroyed). |
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* |
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* As a result, we need to do proper anon_vma locking even |
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* for the new allocation. At the same time, we do not want |
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* to do any locking for the common case of already having |
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* an anon_vma. |
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* |
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* This must be called with the mmap_lock held for reading. |
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*/ |
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int __anon_vma_prepare(struct vm_area_struct *vma) |
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{ |
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struct mm_struct *mm = vma->vm_mm; |
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struct anon_vma *anon_vma, *allocated; |
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struct anon_vma_chain *avc; |
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might_sleep(); |
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avc = anon_vma_chain_alloc(GFP_KERNEL); |
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if (!avc) |
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goto out_enomem; |
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anon_vma = find_mergeable_anon_vma(vma); |
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allocated = NULL; |
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if (!anon_vma) { |
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anon_vma = anon_vma_alloc(); |
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if (unlikely(!anon_vma)) |
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goto out_enomem_free_avc; |
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allocated = anon_vma; |
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} |
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anon_vma_lock_write(anon_vma); |
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/* page_table_lock to protect against threads */ |
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spin_lock(&mm->page_table_lock); |
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if (likely(!vma->anon_vma)) { |
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vma->anon_vma = anon_vma; |
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anon_vma_chain_link(vma, avc, anon_vma); |
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/* vma reference or self-parent link for new root */ |
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anon_vma->degree++; |
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allocated = NULL; |
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avc = NULL; |
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} |
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spin_unlock(&mm->page_table_lock); |
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anon_vma_unlock_write(anon_vma); |
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if (unlikely(allocated)) |
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put_anon_vma(allocated); |
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if (unlikely(avc)) |
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anon_vma_chain_free(avc); |
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return 0; |
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out_enomem_free_avc: |
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anon_vma_chain_free(avc); |
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out_enomem: |
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return -ENOMEM; |
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} |
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/* |
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* This is a useful helper function for locking the anon_vma root as |
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* we traverse the vma->anon_vma_chain, looping over anon_vma's that |
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* have the same vma. |
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* |
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* Such anon_vma's should have the same root, so you'd expect to see |
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* just a single mutex_lock for the whole traversal. |
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*/ |
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static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma) |
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{ |
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struct anon_vma *new_root = anon_vma->root; |
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if (new_root != root) { |
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if (WARN_ON_ONCE(root)) |
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up_write(&root->rwsem); |
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root = new_root; |
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down_write(&root->rwsem); |
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} |
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return root; |
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} |
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static inline void unlock_anon_vma_root(struct anon_vma *root) |
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{ |
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if (root) |
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up_write(&root->rwsem); |
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} |
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/* |
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* Attach the anon_vmas from src to dst. |
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* Returns 0 on success, -ENOMEM on failure. |
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* |
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* anon_vma_clone() is called by __vma_split(), __split_vma(), copy_vma() and |
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* anon_vma_fork(). The first three want an exact copy of src, while the last |
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* one, anon_vma_fork(), may try to reuse an existing anon_vma to prevent |
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* endless growth of anon_vma. Since dst->anon_vma is set to NULL before call, |
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* we can identify this case by checking (!dst->anon_vma && src->anon_vma). |
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* |
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* If (!dst->anon_vma && src->anon_vma) is true, this function tries to find |
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* and reuse existing anon_vma which has no vmas and only one child anon_vma. |
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* This prevents degradation of anon_vma hierarchy to endless linear chain in |
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* case of constantly forking task. On the other hand, an anon_vma with more |
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* than one child isn't reused even if there was no alive vma, thus rmap |
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* walker has a good chance of avoiding scanning the whole hierarchy when it |
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* searches where page is mapped. |
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*/ |
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int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) |
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{ |
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struct anon_vma_chain *avc, *pavc; |
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struct anon_vma *root = NULL; |
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list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { |
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struct anon_vma *anon_vma; |
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avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN); |
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if (unlikely(!avc)) { |
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unlock_anon_vma_root(root); |
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root = NULL; |
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avc = anon_vma_chain_alloc(GFP_KERNEL); |
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if (!avc) |
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goto enomem_failure; |
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} |
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anon_vma = pavc->anon_vma; |
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root = lock_anon_vma_root(root, anon_vma); |
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anon_vma_chain_link(dst, avc, anon_vma); |
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|
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/* |
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* Reuse existing anon_vma if its degree lower than two, |
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* that means it has no vma and only one anon_vma child. |
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* |
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* Do not chose parent anon_vma, otherwise first child |
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* will always reuse it. Root anon_vma is never reused: |
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* it has self-parent reference and at least one child. |
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*/ |
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if (!dst->anon_vma && src->anon_vma && |
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anon_vma != src->anon_vma && anon_vma->degree < 2) |
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dst->anon_vma = anon_vma; |
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} |
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if (dst->anon_vma) |
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dst->anon_vma->degree++; |
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unlock_anon_vma_root(root); |
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return 0; |
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enomem_failure: |
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/* |
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* dst->anon_vma is dropped here otherwise its degree can be incorrectly |
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* decremented in unlink_anon_vmas(). |
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* We can safely do this because callers of anon_vma_clone() don't care |
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* about dst->anon_vma if anon_vma_clone() failed. |
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*/ |
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dst->anon_vma = NULL; |
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unlink_anon_vmas(dst); |
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return -ENOMEM; |
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} |
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/* |
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* Attach vma to its own anon_vma, as well as to the anon_vmas that |
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* the corresponding VMA in the parent process is attached to. |
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* Returns 0 on success, non-zero on failure. |
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*/ |
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int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) |
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{ |
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struct anon_vma_chain *avc; |
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struct anon_vma *anon_vma; |
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int error; |
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/* Don't bother if the parent process has no anon_vma here. */ |
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if (!pvma->anon_vma) |
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return 0; |
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|
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/* Drop inherited anon_vma, we'll reuse existing or allocate new. */ |
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vma->anon_vma = NULL; |
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/* |
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* First, attach the new VMA to the parent VMA's anon_vmas, |
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* so rmap can find non-COWed pages in child processes. |
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*/ |
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error = anon_vma_clone(vma, pvma); |
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if (error) |
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return error; |
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|
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/* An existing anon_vma has been reused, all done then. */ |
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if (vma->anon_vma) |
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return 0; |
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|
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/* Then add our own anon_vma. */ |
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anon_vma = anon_vma_alloc(); |
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if (!anon_vma) |
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goto out_error; |
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avc = anon_vma_chain_alloc(GFP_KERNEL); |
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if (!avc) |
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goto out_error_free_anon_vma; |
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|
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/* |
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* The root anon_vma's rwsem is the lock actually used when we |
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* lock any of the anon_vmas in this anon_vma tree. |
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*/ |
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anon_vma->root = pvma->anon_vma->root; |
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anon_vma->parent = pvma->anon_vma; |
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/* |
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* With refcounts, an anon_vma can stay around longer than the |
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* process it belongs to. The root anon_vma needs to be pinned until |
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* this anon_vma is freed, because the lock lives in the root. |
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*/ |
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get_anon_vma(anon_vma->root); |
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/* Mark this anon_vma as the one where our new (COWed) pages go. */ |
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vma->anon_vma = anon_vma; |
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anon_vma_lock_write(anon_vma); |
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anon_vma_chain_link(vma, avc, anon_vma); |
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anon_vma->parent->degree++; |
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anon_vma_unlock_write(anon_vma); |
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return 0; |
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out_error_free_anon_vma: |
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put_anon_vma(anon_vma); |
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out_error: |
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unlink_anon_vmas(vma); |
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return -ENOMEM; |
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} |
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void unlink_anon_vmas(struct vm_area_struct *vma) |
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{ |
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struct anon_vma_chain *avc, *next; |
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struct anon_vma *root = NULL; |
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|
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/* |
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* Unlink each anon_vma chained to the VMA. This list is ordered |
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* from newest to oldest, ensuring the root anon_vma gets freed last. |
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*/ |
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list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
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struct anon_vma *anon_vma = avc->anon_vma; |
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|
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root = lock_anon_vma_root(root, anon_vma); |
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anon_vma_interval_tree_remove(avc, &anon_vma->rb_root); |
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|
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/* |
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* Leave empty anon_vmas on the list - we'll need |
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* to free them outside the lock. |
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*/ |
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if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) { |
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anon_vma->parent->degree--; |
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continue; |
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} |
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|
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list_del(&avc->same_vma); |
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anon_vma_chain_free(avc); |
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} |
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if (vma->anon_vma) { |
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vma->anon_vma->degree--; |
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|
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/* |
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* vma would still be needed after unlink, and anon_vma will be prepared |
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* when handle fault. |
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*/ |
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vma->anon_vma = NULL; |
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} |
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unlock_anon_vma_root(root); |
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|
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/* |
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* Iterate the list once more, it now only contains empty and unlinked |
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* anon_vmas, destroy them. Could not do before due to __put_anon_vma() |
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* needing to write-acquire the anon_vma->root->rwsem. |
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*/ |
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list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
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struct anon_vma *anon_vma = avc->anon_vma; |
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VM_WARN_ON(anon_vma->degree); |
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put_anon_vma(anon_vma); |
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list_del(&avc->same_vma); |
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anon_vma_chain_free(avc); |
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} |
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} |
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static void anon_vma_ctor(void *data) |
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{ |
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struct anon_vma *anon_vma = data; |
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|
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init_rwsem(&anon_vma->rwsem); |
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atomic_set(&anon_vma->refcount, 0); |
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anon_vma->rb_root = RB_ROOT_CACHED; |
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} |
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void __init anon_vma_init(void) |
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{ |
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anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), |
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0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT, |
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anon_vma_ctor); |
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anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, |
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SLAB_PANIC|SLAB_ACCOUNT); |
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} |
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|
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/* |
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* Getting a lock on a stable anon_vma from a page off the LRU is tricky! |
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* |
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* Since there is no serialization what so ever against page_remove_rmap() |
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* the best this function can do is return a refcount increased anon_vma |
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* that might have been relevant to this page. |
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* |
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* The page might have been remapped to a different anon_vma or the anon_vma |
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* returned may already be freed (and even reused). |
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* |
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* In case it was remapped to a different anon_vma, the new anon_vma will be a |
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* child of the old anon_vma, and the anon_vma lifetime rules will therefore |
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* ensure that any anon_vma obtained from the page will still be valid for as |
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* long as we observe page_mapped() [ hence all those page_mapped() tests ]. |
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* |
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* All users of this function must be very careful when walking the anon_vma |
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* chain and verify that the page in question is indeed mapped in it |
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* [ something equivalent to page_mapped_in_vma() ]. |
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* |
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* Since anon_vma's slab is SLAB_TYPESAFE_BY_RCU and we know from |
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* page_remove_rmap() that the anon_vma pointer from page->mapping is valid |
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* if there is a mapcount, we can dereference the anon_vma after observing |
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* those. |
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*/ |
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struct anon_vma *page_get_anon_vma(struct page *page) |
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{ |
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struct anon_vma *anon_vma = NULL; |
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unsigned long anon_mapping; |
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|
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rcu_read_lock(); |
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anon_mapping = (unsigned long)READ_ONCE(page->mapping); |
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if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
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goto out; |
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if (!page_mapped(page)) |
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goto out; |
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anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
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if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
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anon_vma = NULL; |
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goto out; |
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} |
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|
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/* |
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* If this page is still mapped, then its anon_vma cannot have been |
|
* freed. But if it has been unmapped, we have no security against the |
|
* anon_vma structure being freed and reused (for another anon_vma: |
|
* SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero() |
|
* above cannot corrupt). |
|
*/ |
|
if (!page_mapped(page)) { |
|
rcu_read_unlock(); |
|
put_anon_vma(anon_vma); |
|
return NULL; |
|
} |
|
out: |
|
rcu_read_unlock(); |
|
|
|
return anon_vma; |
|
} |
|
|
|
/* |
|
* Similar to page_get_anon_vma() except it locks the anon_vma. |
|
* |
|
* Its a little more complex as it tries to keep the fast path to a single |
|
* atomic op -- the trylock. If we fail the trylock, we fall back to getting a |
|
* reference like with page_get_anon_vma() and then block on the mutex. |
|
*/ |
|
struct anon_vma *page_lock_anon_vma_read(struct page *page) |
|
{ |
|
struct anon_vma *anon_vma = NULL; |
|
struct anon_vma *root_anon_vma; |
|
unsigned long anon_mapping; |
|
|
|
rcu_read_lock(); |
|
anon_mapping = (unsigned long)READ_ONCE(page->mapping); |
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
|
goto out; |
|
if (!page_mapped(page)) |
|
goto out; |
|
|
|
anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
|
root_anon_vma = READ_ONCE(anon_vma->root); |
|
if (down_read_trylock(&root_anon_vma->rwsem)) { |
|
/* |
|
* If the page is still mapped, then this anon_vma is still |
|
* its anon_vma, and holding the mutex ensures that it will |
|
* not go away, see anon_vma_free(). |
|
*/ |
|
if (!page_mapped(page)) { |
|
up_read(&root_anon_vma->rwsem); |
|
anon_vma = NULL; |
|
} |
|
goto out; |
|
} |
|
|
|
/* trylock failed, we got to sleep */ |
|
if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
|
anon_vma = NULL; |
|
goto out; |
|
} |
|
|
|
if (!page_mapped(page)) { |
|
rcu_read_unlock(); |
|
put_anon_vma(anon_vma); |
|
return NULL; |
|
} |
|
|
|
/* we pinned the anon_vma, its safe to sleep */ |
|
rcu_read_unlock(); |
|
anon_vma_lock_read(anon_vma); |
|
|
|
if (atomic_dec_and_test(&anon_vma->refcount)) { |
|
/* |
|
* Oops, we held the last refcount, release the lock |
|
* and bail -- can't simply use put_anon_vma() because |
|
* we'll deadlock on the anon_vma_lock_write() recursion. |
|
*/ |
|
anon_vma_unlock_read(anon_vma); |
|
__put_anon_vma(anon_vma); |
|
anon_vma = NULL; |
|
} |
|
|
|
return anon_vma; |
|
|
|
out: |
|
rcu_read_unlock(); |
|
return anon_vma; |
|
} |
|
|
|
void page_unlock_anon_vma_read(struct anon_vma *anon_vma) |
|
{ |
|
anon_vma_unlock_read(anon_vma); |
|
} |
|
|
|
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH |
|
/* |
|
* Flush TLB entries for recently unmapped pages from remote CPUs. It is |
|
* important if a PTE was dirty when it was unmapped that it's flushed |
|
* before any IO is initiated on the page to prevent lost writes. Similarly, |
|
* it must be flushed before freeing to prevent data leakage. |
|
*/ |
|
void try_to_unmap_flush(void) |
|
{ |
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; |
|
|
|
if (!tlb_ubc->flush_required) |
|
return; |
|
|
|
arch_tlbbatch_flush(&tlb_ubc->arch); |
|
tlb_ubc->flush_required = false; |
|
tlb_ubc->writable = false; |
|
} |
|
|
|
/* Flush iff there are potentially writable TLB entries that can race with IO */ |
|
void try_to_unmap_flush_dirty(void) |
|
{ |
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; |
|
|
|
if (tlb_ubc->writable) |
|
try_to_unmap_flush(); |
|
} |
|
|
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) |
|
{ |
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; |
|
|
|
arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); |
|
tlb_ubc->flush_required = true; |
|
|
|
/* |
|
* Ensure compiler does not re-order the setting of tlb_flush_batched |
|
* before the PTE is cleared. |
|
*/ |
|
barrier(); |
|
mm->tlb_flush_batched = true; |
|
|
|
/* |
|
* If the PTE was dirty then it's best to assume it's writable. The |
|
* caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush() |
|
* before the page is queued for IO. |
|
*/ |
|
if (writable) |
|
tlb_ubc->writable = true; |
|
} |
|
|
|
/* |
|
* Returns true if the TLB flush should be deferred to the end of a batch of |
|
* unmap operations to reduce IPIs. |
|
*/ |
|
static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) |
|
{ |
|
bool should_defer = false; |
|
|
|
if (!(flags & TTU_BATCH_FLUSH)) |
|
return false; |
|
|
|
/* If remote CPUs need to be flushed then defer batch the flush */ |
|
if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) |
|
should_defer = true; |
|
put_cpu(); |
|
|
|
return should_defer; |
|
} |
|
|
|
/* |
|
* Reclaim unmaps pages under the PTL but do not flush the TLB prior to |
|
* releasing the PTL if TLB flushes are batched. It's possible for a parallel |
|
* operation such as mprotect or munmap to race between reclaim unmapping |
|
* the page and flushing the page. If this race occurs, it potentially allows |
|
* access to data via a stale TLB entry. Tracking all mm's that have TLB |
|
* batching in flight would be expensive during reclaim so instead track |
|
* whether TLB batching occurred in the past and if so then do a flush here |
|
* if required. This will cost one additional flush per reclaim cycle paid |
|
* by the first operation at risk such as mprotect and mumap. |
|
* |
|
* This must be called under the PTL so that an access to tlb_flush_batched |
|
* that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise |
|
* via the PTL. |
|
*/ |
|
void flush_tlb_batched_pending(struct mm_struct *mm) |
|
{ |
|
if (data_race(mm->tlb_flush_batched)) { |
|
flush_tlb_mm(mm); |
|
|
|
/* |
|
* Do not allow the compiler to re-order the clearing of |
|
* tlb_flush_batched before the tlb is flushed. |
|
*/ |
|
barrier(); |
|
mm->tlb_flush_batched = false; |
|
} |
|
} |
|
#else |
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) |
|
{ |
|
} |
|
|
|
static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) |
|
{ |
|
return false; |
|
} |
|
#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */ |
|
|
|
/* |
|
* At what user virtual address is page expected in vma? |
|
* Caller should check the page is actually part of the vma. |
|
*/ |
|
unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) |
|
{ |
|
unsigned long address; |
|
if (PageAnon(page)) { |
|
struct anon_vma *page__anon_vma = page_anon_vma(page); |
|
/* |
|
* Note: swapoff's unuse_vma() is more efficient with this |
|
* check, and needs it to match anon_vma when KSM is active. |
|
*/ |
|
if (!vma->anon_vma || !page__anon_vma || |
|
vma->anon_vma->root != page__anon_vma->root) |
|
return -EFAULT; |
|
} else if (page->mapping) { |
|
if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping) |
|
return -EFAULT; |
|
} else |
|
return -EFAULT; |
|
address = __vma_address(page, vma); |
|
if (unlikely(address < vma->vm_start || address >= vma->vm_end)) |
|
return -EFAULT; |
|
return address; |
|
} |
|
|
|
pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) |
|
{ |
|
pgd_t *pgd; |
|
p4d_t *p4d; |
|
pud_t *pud; |
|
pmd_t *pmd = NULL; |
|
pmd_t pmde; |
|
|
|
pgd = pgd_offset(mm, address); |
|
if (!pgd_present(*pgd)) |
|
goto out; |
|
|
|
p4d = p4d_offset(pgd, address); |
|
if (!p4d_present(*p4d)) |
|
goto out; |
|
|
|
pud = pud_offset(p4d, address); |
|
if (!pud_present(*pud)) |
|
goto out; |
|
|
|
pmd = pmd_offset(pud, address); |
|
/* |
|
* Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at() |
|
* without holding anon_vma lock for write. So when looking for a |
|
* genuine pmde (in which to find pte), test present and !THP together. |
|
*/ |
|
pmde = *pmd; |
|
barrier(); |
|
if (!pmd_present(pmde) || pmd_trans_huge(pmde)) |
|
pmd = NULL; |
|
out: |
|
return pmd; |
|
} |
|
|
|
struct page_referenced_arg { |
|
int mapcount; |
|
int referenced; |
|
unsigned long vm_flags; |
|
struct mem_cgroup *memcg; |
|
}; |
|
/* |
|
* arg: page_referenced_arg will be passed |
|
*/ |
|
static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, |
|
unsigned long address, void *arg) |
|
{ |
|
struct page_referenced_arg *pra = arg; |
|
struct page_vma_mapped_walk pvmw = { |
|
.page = page, |
|
.vma = vma, |
|
.address = address, |
|
}; |
|
int referenced = 0; |
|
|
|
while (page_vma_mapped_walk(&pvmw)) { |
|
address = pvmw.address; |
|
|
|
if (vma->vm_flags & VM_LOCKED) { |
|
page_vma_mapped_walk_done(&pvmw); |
|
pra->vm_flags |= VM_LOCKED; |
|
return false; /* To break the loop */ |
|
} |
|
|
|
if (pvmw.pte) { |
|
if (ptep_clear_flush_young_notify(vma, address, |
|
pvmw.pte)) { |
|
/* |
|
* Don't treat a reference through |
|
* a sequentially read mapping as such. |
|
* If the page has been used in another mapping, |
|
* we will catch it; if this other mapping is |
|
* already gone, the unmap path will have set |
|
* PG_referenced or activated the page. |
|
*/ |
|
if (likely(!(vma->vm_flags & VM_SEQ_READ))) |
|
referenced++; |
|
} |
|
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { |
|
if (pmdp_clear_flush_young_notify(vma, address, |
|
pvmw.pmd)) |
|
referenced++; |
|
} else { |
|
/* unexpected pmd-mapped page? */ |
|
WARN_ON_ONCE(1); |
|
} |
|
|
|
pra->mapcount--; |
|
} |
|
|
|
if (referenced) |
|
clear_page_idle(page); |
|
if (test_and_clear_page_young(page)) |
|
referenced++; |
|
|
|
if (referenced) { |
|
pra->referenced++; |
|
pra->vm_flags |= vma->vm_flags; |
|
} |
|
|
|
if (!pra->mapcount) |
|
return false; /* To break the loop */ |
|
|
|
return true; |
|
} |
|
|
|
static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) |
|
{ |
|
struct page_referenced_arg *pra = arg; |
|
struct mem_cgroup *memcg = pra->memcg; |
|
|
|
if (!mm_match_cgroup(vma->vm_mm, memcg)) |
|
return true; |
|
|
|
return false; |
|
} |
|
|
|
/** |
|
* page_referenced - test if the page was referenced |
|
* @page: the page to test |
|
* @is_locked: caller holds lock on the page |
|
* @memcg: target memory cgroup |
|
* @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
|
* |
|
* Quick test_and_clear_referenced for all mappings to a page, |
|
* returns the number of ptes which referenced the page. |
|
*/ |
|
int page_referenced(struct page *page, |
|
int is_locked, |
|
struct mem_cgroup *memcg, |
|
unsigned long *vm_flags) |
|
{ |
|
int we_locked = 0; |
|
struct page_referenced_arg pra = { |
|
.mapcount = total_mapcount(page), |
|
.memcg = memcg, |
|
}; |
|
struct rmap_walk_control rwc = { |
|
.rmap_one = page_referenced_one, |
|
.arg = (void *)&pra, |
|
.anon_lock = page_lock_anon_vma_read, |
|
}; |
|
|
|
*vm_flags = 0; |
|
if (!pra.mapcount) |
|
return 0; |
|
|
|
if (!page_rmapping(page)) |
|
return 0; |
|
|
|
if (!is_locked && (!PageAnon(page) || PageKsm(page))) { |
|
we_locked = trylock_page(page); |
|
if (!we_locked) |
|
return 1; |
|
} |
|
|
|
/* |
|
* If we are reclaiming on behalf of a cgroup, skip |
|
* counting on behalf of references from different |
|
* cgroups |
|
*/ |
|
if (memcg) { |
|
rwc.invalid_vma = invalid_page_referenced_vma; |
|
} |
|
|
|
rmap_walk(page, &rwc); |
|
*vm_flags = pra.vm_flags; |
|
|
|
if (we_locked) |
|
unlock_page(page); |
|
|
|
return pra.referenced; |
|
} |
|
|
|
static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, |
|
unsigned long address, void *arg) |
|
{ |
|
struct page_vma_mapped_walk pvmw = { |
|
.page = page, |
|
.vma = vma, |
|
.address = address, |
|
.flags = PVMW_SYNC, |
|
}; |
|
struct mmu_notifier_range range; |
|
int *cleaned = arg; |
|
|
|
/* |
|
* We have to assume the worse case ie pmd for invalidation. Note that |
|
* the page can not be free from this function. |
|
*/ |
|
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, |
|
0, vma, vma->vm_mm, address, |
|
min(vma->vm_end, address + page_size(page))); |
|
mmu_notifier_invalidate_range_start(&range); |
|
|
|
while (page_vma_mapped_walk(&pvmw)) { |
|
int ret = 0; |
|
|
|
address = pvmw.address; |
|
if (pvmw.pte) { |
|
pte_t entry; |
|
pte_t *pte = pvmw.pte; |
|
|
|
if (!pte_dirty(*pte) && !pte_write(*pte)) |
|
continue; |
|
|
|
flush_cache_page(vma, address, pte_pfn(*pte)); |
|
entry = ptep_clear_flush(vma, address, pte); |
|
entry = pte_wrprotect(entry); |
|
entry = pte_mkclean(entry); |
|
set_pte_at(vma->vm_mm, address, pte, entry); |
|
ret = 1; |
|
} else { |
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE |
|
pmd_t *pmd = pvmw.pmd; |
|
pmd_t entry; |
|
|
|
if (!pmd_dirty(*pmd) && !pmd_write(*pmd)) |
|
continue; |
|
|
|
flush_cache_page(vma, address, page_to_pfn(page)); |
|
entry = pmdp_invalidate(vma, address, pmd); |
|
entry = pmd_wrprotect(entry); |
|
entry = pmd_mkclean(entry); |
|
set_pmd_at(vma->vm_mm, address, pmd, entry); |
|
ret = 1; |
|
#else |
|
/* unexpected pmd-mapped page? */ |
|
WARN_ON_ONCE(1); |
|
#endif |
|
} |
|
|
|
/* |
|
* No need to call mmu_notifier_invalidate_range() as we are |
|
* downgrading page table protection not changing it to point |
|
* to a new page. |
|
* |
|
* See Documentation/vm/mmu_notifier.rst |
|
*/ |
|
if (ret) |
|
(*cleaned)++; |
|
} |
|
|
|
mmu_notifier_invalidate_range_end(&range); |
|
|
|
return true; |
|
} |
|
|
|
static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg) |
|
{ |
|
if (vma->vm_flags & VM_SHARED) |
|
return false; |
|
|
|
return true; |
|
} |
|
|
|
int page_mkclean(struct page *page) |
|
{ |
|
int cleaned = 0; |
|
struct address_space *mapping; |
|
struct rmap_walk_control rwc = { |
|
.arg = (void *)&cleaned, |
|
.rmap_one = page_mkclean_one, |
|
.invalid_vma = invalid_mkclean_vma, |
|
}; |
|
|
|
BUG_ON(!PageLocked(page)); |
|
|
|
if (!page_mapped(page)) |
|
return 0; |
|
|
|
mapping = page_mapping(page); |
|
if (!mapping) |
|
return 0; |
|
|
|
rmap_walk(page, &rwc); |
|
|
|
return cleaned; |
|
} |
|
EXPORT_SYMBOL_GPL(page_mkclean); |
|
|
|
/** |
|
* page_move_anon_rmap - move a page to our anon_vma |
|
* @page: the page to move to our anon_vma |
|
* @vma: the vma the page belongs to |
|
* |
|
* When a page belongs exclusively to one process after a COW event, |
|
* that page can be moved into the anon_vma that belongs to just that |
|
* process, so the rmap code will not search the parent or sibling |
|
* processes. |
|
*/ |
|
void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma) |
|
{ |
|
struct anon_vma *anon_vma = vma->anon_vma; |
|
|
|
page = compound_head(page); |
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
VM_BUG_ON_VMA(!anon_vma, vma); |
|
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
|
/* |
|
* Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written |
|
* simultaneously, so a concurrent reader (eg page_referenced()'s |
|
* PageAnon()) will not see one without the other. |
|
*/ |
|
WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); |
|
} |
|
|
|
/** |
|
* __page_set_anon_rmap - set up new anonymous rmap |
|
* @page: Page or Hugepage to add to rmap |
|
* @vma: VM area to add page to. |
|
* @address: User virtual address of the mapping |
|
* @exclusive: the page is exclusively owned by the current process |
|
*/ |
|
static void __page_set_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address, int exclusive) |
|
{ |
|
struct anon_vma *anon_vma = vma->anon_vma; |
|
|
|
BUG_ON(!anon_vma); |
|
|
|
if (PageAnon(page)) |
|
return; |
|
|
|
/* |
|
* If the page isn't exclusively mapped into this vma, |
|
* we must use the _oldest_ possible anon_vma for the |
|
* page mapping! |
|
*/ |
|
if (!exclusive) |
|
anon_vma = anon_vma->root; |
|
|
|
/* |
|
* page_idle does a lockless/optimistic rmap scan on page->mapping. |
|
* Make sure the compiler doesn't split the stores of anon_vma and |
|
* the PAGE_MAPPING_ANON type identifier, otherwise the rmap code |
|
* could mistake the mapping for a struct address_space and crash. |
|
*/ |
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
|
WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); |
|
page->index = linear_page_index(vma, address); |
|
} |
|
|
|
/** |
|
* __page_check_anon_rmap - sanity check anonymous rmap addition |
|
* @page: the page to add the mapping to |
|
* @vma: the vm area in which the mapping is added |
|
* @address: the user virtual address mapped |
|
*/ |
|
static void __page_check_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address) |
|
{ |
|
/* |
|
* The page's anon-rmap details (mapping and index) are guaranteed to |
|
* be set up correctly at this point. |
|
* |
|
* We have exclusion against page_add_anon_rmap because the caller |
|
* always holds the page locked. |
|
* |
|
* We have exclusion against page_add_new_anon_rmap because those pages |
|
* are initially only visible via the pagetables, and the pte is locked |
|
* over the call to page_add_new_anon_rmap. |
|
*/ |
|
VM_BUG_ON_PAGE(page_anon_vma(page)->root != vma->anon_vma->root, page); |
|
VM_BUG_ON_PAGE(page_to_pgoff(page) != linear_page_index(vma, address), |
|
page); |
|
} |
|
|
|
/** |
|
* page_add_anon_rmap - add pte mapping to an anonymous page |
|
* @page: the page to add the mapping to |
|
* @vma: the vm area in which the mapping is added |
|
* @address: the user virtual address mapped |
|
* @compound: charge the page as compound or small page |
|
* |
|
* The caller needs to hold the pte lock, and the page must be locked in |
|
* the anon_vma case: to serialize mapping,index checking after setting, |
|
* and to ensure that PageAnon is not being upgraded racily to PageKsm |
|
* (but PageKsm is never downgraded to PageAnon). |
|
*/ |
|
void page_add_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address, bool compound) |
|
{ |
|
do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0); |
|
} |
|
|
|
/* |
|
* Special version of the above for do_swap_page, which often runs |
|
* into pages that are exclusively owned by the current process. |
|
* Everybody else should continue to use page_add_anon_rmap above. |
|
*/ |
|
void do_page_add_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address, int flags) |
|
{ |
|
bool compound = flags & RMAP_COMPOUND; |
|
bool first; |
|
|
|
if (unlikely(PageKsm(page))) |
|
lock_page_memcg(page); |
|
else |
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
|
|
if (compound) { |
|
atomic_t *mapcount; |
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page); |
|
mapcount = compound_mapcount_ptr(page); |
|
first = atomic_inc_and_test(mapcount); |
|
} else { |
|
first = atomic_inc_and_test(&page->_mapcount); |
|
} |
|
|
|
if (first) { |
|
int nr = compound ? thp_nr_pages(page) : 1; |
|
/* |
|
* We use the irq-unsafe __{inc|mod}_zone_page_stat because |
|
* these counters are not modified in interrupt context, and |
|
* pte lock(a spinlock) is held, which implies preemption |
|
* disabled. |
|
*/ |
|
if (compound) |
|
__mod_lruvec_page_state(page, NR_ANON_THPS, nr); |
|
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr); |
|
} |
|
|
|
if (unlikely(PageKsm(page))) { |
|
unlock_page_memcg(page); |
|
return; |
|
} |
|
|
|
/* address might be in next vma when migration races vma_adjust */ |
|
if (first) |
|
__page_set_anon_rmap(page, vma, address, |
|
flags & RMAP_EXCLUSIVE); |
|
else |
|
__page_check_anon_rmap(page, vma, address); |
|
} |
|
|
|
/** |
|
* page_add_new_anon_rmap - add pte mapping to a new anonymous page |
|
* @page: the page to add the mapping to |
|
* @vma: the vm area in which the mapping is added |
|
* @address: the user virtual address mapped |
|
* @compound: charge the page as compound or small page |
|
* |
|
* Same as page_add_anon_rmap but must only be called on *new* pages. |
|
* This means the inc-and-test can be bypassed. |
|
* Page does not have to be locked. |
|
*/ |
|
void page_add_new_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address, bool compound) |
|
{ |
|
int nr = compound ? thp_nr_pages(page) : 1; |
|
|
|
VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); |
|
__SetPageSwapBacked(page); |
|
if (compound) { |
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page); |
|
/* increment count (starts at -1) */ |
|
atomic_set(compound_mapcount_ptr(page), 0); |
|
if (hpage_pincount_available(page)) |
|
atomic_set(compound_pincount_ptr(page), 0); |
|
|
|
__mod_lruvec_page_state(page, NR_ANON_THPS, nr); |
|
} else { |
|
/* Anon THP always mapped first with PMD */ |
|
VM_BUG_ON_PAGE(PageTransCompound(page), page); |
|
/* increment count (starts at -1) */ |
|
atomic_set(&page->_mapcount, 0); |
|
} |
|
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr); |
|
__page_set_anon_rmap(page, vma, address, 1); |
|
} |
|
|
|
/** |
|
* page_add_file_rmap - add pte mapping to a file page |
|
* @page: the page to add the mapping to |
|
* @compound: charge the page as compound or small page |
|
* |
|
* The caller needs to hold the pte lock. |
|
*/ |
|
void page_add_file_rmap(struct page *page, bool compound) |
|
{ |
|
int i, nr = 1; |
|
|
|
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page); |
|
lock_page_memcg(page); |
|
if (compound && PageTransHuge(page)) { |
|
int nr_pages = thp_nr_pages(page); |
|
|
|
for (i = 0, nr = 0; i < nr_pages; i++) { |
|
if (atomic_inc_and_test(&page[i]._mapcount)) |
|
nr++; |
|
} |
|
if (!atomic_inc_and_test(compound_mapcount_ptr(page))) |
|
goto out; |
|
if (PageSwapBacked(page)) |
|
__mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, |
|
nr_pages); |
|
else |
|
__mod_lruvec_page_state(page, NR_FILE_PMDMAPPED, |
|
nr_pages); |
|
} else { |
|
if (PageTransCompound(page) && page_mapping(page)) { |
|
VM_WARN_ON_ONCE(!PageLocked(page)); |
|
|
|
SetPageDoubleMap(compound_head(page)); |
|
if (PageMlocked(page)) |
|
clear_page_mlock(compound_head(page)); |
|
} |
|
if (!atomic_inc_and_test(&page->_mapcount)) |
|
goto out; |
|
} |
|
__mod_lruvec_page_state(page, NR_FILE_MAPPED, nr); |
|
out: |
|
unlock_page_memcg(page); |
|
} |
|
|
|
static void page_remove_file_rmap(struct page *page, bool compound) |
|
{ |
|
int i, nr = 1; |
|
|
|
VM_BUG_ON_PAGE(compound && !PageHead(page), page); |
|
|
|
/* Hugepages are not counted in NR_FILE_MAPPED for now. */ |
|
if (unlikely(PageHuge(page))) { |
|
/* hugetlb pages are always mapped with pmds */ |
|
atomic_dec(compound_mapcount_ptr(page)); |
|
return; |
|
} |
|
|
|
/* page still mapped by someone else? */ |
|
if (compound && PageTransHuge(page)) { |
|
int nr_pages = thp_nr_pages(page); |
|
|
|
for (i = 0, nr = 0; i < nr_pages; i++) { |
|
if (atomic_add_negative(-1, &page[i]._mapcount)) |
|
nr++; |
|
} |
|
if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) |
|
return; |
|
if (PageSwapBacked(page)) |
|
__mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, |
|
-nr_pages); |
|
else |
|
__mod_lruvec_page_state(page, NR_FILE_PMDMAPPED, |
|
-nr_pages); |
|
} else { |
|
if (!atomic_add_negative(-1, &page->_mapcount)) |
|
return; |
|
} |
|
|
|
/* |
|
* We use the irq-unsafe __{inc|mod}_lruvec_page_state because |
|
* these counters are not modified in interrupt context, and |
|
* pte lock(a spinlock) is held, which implies preemption disabled. |
|
*/ |
|
__mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr); |
|
|
|
if (unlikely(PageMlocked(page))) |
|
clear_page_mlock(page); |
|
} |
|
|
|
static void page_remove_anon_compound_rmap(struct page *page) |
|
{ |
|
int i, nr; |
|
|
|
if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) |
|
return; |
|
|
|
/* Hugepages are not counted in NR_ANON_PAGES for now. */ |
|
if (unlikely(PageHuge(page))) |
|
return; |
|
|
|
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) |
|
return; |
|
|
|
__mod_lruvec_page_state(page, NR_ANON_THPS, -thp_nr_pages(page)); |
|
|
|
if (TestClearPageDoubleMap(page)) { |
|
/* |
|
* Subpages can be mapped with PTEs too. Check how many of |
|
* them are still mapped. |
|
*/ |
|
for (i = 0, nr = 0; i < thp_nr_pages(page); i++) { |
|
if (atomic_add_negative(-1, &page[i]._mapcount)) |
|
nr++; |
|
} |
|
|
|
/* |
|
* Queue the page for deferred split if at least one small |
|
* page of the compound page is unmapped, but at least one |
|
* small page is still mapped. |
|
*/ |
|
if (nr && nr < thp_nr_pages(page)) |
|
deferred_split_huge_page(page); |
|
} else { |
|
nr = thp_nr_pages(page); |
|
} |
|
|
|
if (unlikely(PageMlocked(page))) |
|
clear_page_mlock(page); |
|
|
|
if (nr) |
|
__mod_lruvec_page_state(page, NR_ANON_MAPPED, -nr); |
|
} |
|
|
|
/** |
|
* page_remove_rmap - take down pte mapping from a page |
|
* @page: page to remove mapping from |
|
* @compound: uncharge the page as compound or small page |
|
* |
|
* The caller needs to hold the pte lock. |
|
*/ |
|
void page_remove_rmap(struct page *page, bool compound) |
|
{ |
|
lock_page_memcg(page); |
|
|
|
if (!PageAnon(page)) { |
|
page_remove_file_rmap(page, compound); |
|
goto out; |
|
} |
|
|
|
if (compound) { |
|
page_remove_anon_compound_rmap(page); |
|
goto out; |
|
} |
|
|
|
/* page still mapped by someone else? */ |
|
if (!atomic_add_negative(-1, &page->_mapcount)) |
|
goto out; |
|
|
|
/* |
|
* We use the irq-unsafe __{inc|mod}_zone_page_stat because |
|
* these counters are not modified in interrupt context, and |
|
* pte lock(a spinlock) is held, which implies preemption disabled. |
|
*/ |
|
__dec_lruvec_page_state(page, NR_ANON_MAPPED); |
|
|
|
if (unlikely(PageMlocked(page))) |
|
clear_page_mlock(page); |
|
|
|
if (PageTransCompound(page)) |
|
deferred_split_huge_page(compound_head(page)); |
|
|
|
/* |
|
* It would be tidy to reset the PageAnon mapping here, |
|
* but that might overwrite a racing page_add_anon_rmap |
|
* which increments mapcount after us but sets mapping |
|
* before us: so leave the reset to free_unref_page, |
|
* and remember that it's only reliable while mapped. |
|
* Leaving it set also helps swapoff to reinstate ptes |
|
* faster for those pages still in swapcache. |
|
*/ |
|
out: |
|
unlock_page_memcg(page); |
|
} |
|
|
|
/* |
|
* @arg: enum ttu_flags will be passed to this argument |
|
*/ |
|
static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
|
unsigned long address, void *arg) |
|
{ |
|
struct mm_struct *mm = vma->vm_mm; |
|
struct page_vma_mapped_walk pvmw = { |
|
.page = page, |
|
.vma = vma, |
|
.address = address, |
|
}; |
|
pte_t pteval; |
|
struct page *subpage; |
|
bool ret = true; |
|
struct mmu_notifier_range range; |
|
enum ttu_flags flags = (enum ttu_flags)(long)arg; |
|
|
|
/* munlock has nothing to gain from examining un-locked vmas */ |
|
if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED)) |
|
return true; |
|
|
|
if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) && |
|
is_zone_device_page(page) && !is_device_private_page(page)) |
|
return true; |
|
|
|
if (flags & TTU_SPLIT_HUGE_PMD) { |
|
split_huge_pmd_address(vma, address, |
|
flags & TTU_SPLIT_FREEZE, page); |
|
} |
|
|
|
/* |
|
* For THP, we have to assume the worse case ie pmd for invalidation. |
|
* For hugetlb, it could be much worse if we need to do pud |
|
* invalidation in the case of pmd sharing. |
|
* |
|
* Note that the page can not be free in this function as call of |
|
* try_to_unmap() must hold a reference on the page. |
|
*/ |
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, |
|
address, |
|
min(vma->vm_end, address + page_size(page))); |
|
if (PageHuge(page)) { |
|
/* |
|
* If sharing is possible, start and end will be adjusted |
|
* accordingly. |
|
*/ |
|
adjust_range_if_pmd_sharing_possible(vma, &range.start, |
|
&range.end); |
|
} |
|
mmu_notifier_invalidate_range_start(&range); |
|
|
|
while (page_vma_mapped_walk(&pvmw)) { |
|
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION |
|
/* PMD-mapped THP migration entry */ |
|
if (!pvmw.pte && (flags & TTU_MIGRATION)) { |
|
VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page); |
|
|
|
set_pmd_migration_entry(&pvmw, page); |
|
continue; |
|
} |
|
#endif |
|
|
|
/* |
|
* If the page is mlock()d, we cannot swap it out. |
|
* If it's recently referenced (perhaps page_referenced |
|
* skipped over this mm) then we should reactivate it. |
|
*/ |
|
if (!(flags & TTU_IGNORE_MLOCK)) { |
|
if (vma->vm_flags & VM_LOCKED) { |
|
/* PTE-mapped THP are never mlocked */ |
|
if (!PageTransCompound(page)) { |
|
/* |
|
* Holding pte lock, we do *not* need |
|
* mmap_lock here |
|
*/ |
|
mlock_vma_page(page); |
|
} |
|
ret = false; |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
if (flags & TTU_MUNLOCK) |
|
continue; |
|
} |
|
|
|
/* Unexpected PMD-mapped THP? */ |
|
VM_BUG_ON_PAGE(!pvmw.pte, page); |
|
|
|
subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); |
|
address = pvmw.address; |
|
|
|
if (PageHuge(page) && !PageAnon(page)) { |
|
/* |
|
* To call huge_pmd_unshare, i_mmap_rwsem must be |
|
* held in write mode. Caller needs to explicitly |
|
* do this outside rmap routines. |
|
*/ |
|
VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); |
|
if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) { |
|
/* |
|
* huge_pmd_unshare unmapped an entire PMD |
|
* page. There is no way of knowing exactly |
|
* which PMDs may be cached for this mm, so |
|
* we must flush them all. start/end were |
|
* already adjusted above to cover this range. |
|
*/ |
|
flush_cache_range(vma, range.start, range.end); |
|
flush_tlb_range(vma, range.start, range.end); |
|
mmu_notifier_invalidate_range(mm, range.start, |
|
range.end); |
|
|
|
/* |
|
* The ref count of the PMD page was dropped |
|
* which is part of the way map counting |
|
* is done for shared PMDs. Return 'true' |
|
* here. When there is no other sharing, |
|
* huge_pmd_unshare returns false and we will |
|
* unmap the actual page and drop map count |
|
* to zero. |
|
*/ |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
} |
|
|
|
if (IS_ENABLED(CONFIG_MIGRATION) && |
|
(flags & TTU_MIGRATION) && |
|
is_zone_device_page(page)) { |
|
swp_entry_t entry; |
|
pte_t swp_pte; |
|
|
|
pteval = ptep_get_and_clear(mm, pvmw.address, pvmw.pte); |
|
|
|
/* |
|
* Store the pfn of the page in a special migration |
|
* pte. do_swap_page() will wait until the migration |
|
* pte is removed and then restart fault handling. |
|
*/ |
|
entry = make_migration_entry(page, 0); |
|
swp_pte = swp_entry_to_pte(entry); |
|
|
|
/* |
|
* pteval maps a zone device page and is therefore |
|
* a swap pte. |
|
*/ |
|
if (pte_swp_soft_dirty(pteval)) |
|
swp_pte = pte_swp_mksoft_dirty(swp_pte); |
|
if (pte_swp_uffd_wp(pteval)) |
|
swp_pte = pte_swp_mkuffd_wp(swp_pte); |
|
set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte); |
|
/* |
|
* No need to invalidate here it will synchronize on |
|
* against the special swap migration pte. |
|
* |
|
* The assignment to subpage above was computed from a |
|
* swap PTE which results in an invalid pointer. |
|
* Since only PAGE_SIZE pages can currently be |
|
* migrated, just set it to page. This will need to be |
|
* changed when hugepage migrations to device private |
|
* memory are supported. |
|
*/ |
|
subpage = page; |
|
goto discard; |
|
} |
|
|
|
/* Nuke the page table entry. */ |
|
flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); |
|
if (should_defer_flush(mm, flags)) { |
|
/* |
|
* We clear the PTE but do not flush so potentially |
|
* a remote CPU could still be writing to the page. |
|
* If the entry was previously clean then the |
|
* architecture must guarantee that a clear->dirty |
|
* transition on a cached TLB entry is written through |
|
* and traps if the PTE is unmapped. |
|
*/ |
|
pteval = ptep_get_and_clear(mm, address, pvmw.pte); |
|
|
|
set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); |
|
} else { |
|
pteval = ptep_clear_flush(vma, address, pvmw.pte); |
|
} |
|
|
|
/* Move the dirty bit to the page. Now the pte is gone. */ |
|
if (pte_dirty(pteval)) |
|
set_page_dirty(page); |
|
|
|
/* Update high watermark before we lower rss */ |
|
update_hiwater_rss(mm); |
|
|
|
if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
|
pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); |
|
if (PageHuge(page)) { |
|
hugetlb_count_sub(compound_nr(page), mm); |
|
set_huge_swap_pte_at(mm, address, |
|
pvmw.pte, pteval, |
|
vma_mmu_pagesize(vma)); |
|
} else { |
|
dec_mm_counter(mm, mm_counter(page)); |
|
set_pte_at(mm, address, pvmw.pte, pteval); |
|
} |
|
|
|
} else if (pte_unused(pteval) && !userfaultfd_armed(vma)) { |
|
/* |
|
* The guest indicated that the page content is of no |
|
* interest anymore. Simply discard the pte, vmscan |
|
* will take care of the rest. |
|
* A future reference will then fault in a new zero |
|
* page. When userfaultfd is active, we must not drop |
|
* this page though, as its main user (postcopy |
|
* migration) will not expect userfaults on already |
|
* copied pages. |
|
*/ |
|
dec_mm_counter(mm, mm_counter(page)); |
|
/* We have to invalidate as we cleared the pte */ |
|
mmu_notifier_invalidate_range(mm, address, |
|
address + PAGE_SIZE); |
|
} else if (IS_ENABLED(CONFIG_MIGRATION) && |
|
(flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))) { |
|
swp_entry_t entry; |
|
pte_t swp_pte; |
|
|
|
if (arch_unmap_one(mm, vma, address, pteval) < 0) { |
|
set_pte_at(mm, address, pvmw.pte, pteval); |
|
ret = false; |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
|
|
/* |
|
* Store the pfn of the page in a special migration |
|
* pte. do_swap_page() will wait until the migration |
|
* pte is removed and then restart fault handling. |
|
*/ |
|
entry = make_migration_entry(subpage, |
|
pte_write(pteval)); |
|
swp_pte = swp_entry_to_pte(entry); |
|
if (pte_soft_dirty(pteval)) |
|
swp_pte = pte_swp_mksoft_dirty(swp_pte); |
|
if (pte_uffd_wp(pteval)) |
|
swp_pte = pte_swp_mkuffd_wp(swp_pte); |
|
set_pte_at(mm, address, pvmw.pte, swp_pte); |
|
/* |
|
* No need to invalidate here it will synchronize on |
|
* against the special swap migration pte. |
|
*/ |
|
} else if (PageAnon(page)) { |
|
swp_entry_t entry = { .val = page_private(subpage) }; |
|
pte_t swp_pte; |
|
/* |
|
* Store the swap location in the pte. |
|
* See handle_pte_fault() ... |
|
*/ |
|
if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) { |
|
WARN_ON_ONCE(1); |
|
ret = false; |
|
/* We have to invalidate as we cleared the pte */ |
|
mmu_notifier_invalidate_range(mm, address, |
|
address + PAGE_SIZE); |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
|
|
/* MADV_FREE page check */ |
|
if (!PageSwapBacked(page)) { |
|
if (!PageDirty(page)) { |
|
/* Invalidate as we cleared the pte */ |
|
mmu_notifier_invalidate_range(mm, |
|
address, address + PAGE_SIZE); |
|
dec_mm_counter(mm, MM_ANONPAGES); |
|
goto discard; |
|
} |
|
|
|
/* |
|
* If the page was redirtied, it cannot be |
|
* discarded. Remap the page to page table. |
|
*/ |
|
set_pte_at(mm, address, pvmw.pte, pteval); |
|
SetPageSwapBacked(page); |
|
ret = false; |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
|
|
if (swap_duplicate(entry) < 0) { |
|
set_pte_at(mm, address, pvmw.pte, pteval); |
|
ret = false; |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
if (arch_unmap_one(mm, vma, address, pteval) < 0) { |
|
set_pte_at(mm, address, pvmw.pte, pteval); |
|
ret = false; |
|
page_vma_mapped_walk_done(&pvmw); |
|
break; |
|
} |
|
if (list_empty(&mm->mmlist)) { |
|
spin_lock(&mmlist_lock); |
|
if (list_empty(&mm->mmlist)) |
|
list_add(&mm->mmlist, &init_mm.mmlist); |
|
spin_unlock(&mmlist_lock); |
|
} |
|
dec_mm_counter(mm, MM_ANONPAGES); |
|
inc_mm_counter(mm, MM_SWAPENTS); |
|
swp_pte = swp_entry_to_pte(entry); |
|
if (pte_soft_dirty(pteval)) |
|
swp_pte = pte_swp_mksoft_dirty(swp_pte); |
|
if (pte_uffd_wp(pteval)) |
|
swp_pte = pte_swp_mkuffd_wp(swp_pte); |
|
set_pte_at(mm, address, pvmw.pte, swp_pte); |
|
/* Invalidate as we cleared the pte */ |
|
mmu_notifier_invalidate_range(mm, address, |
|
address + PAGE_SIZE); |
|
} else { |
|
/* |
|
* This is a locked file-backed page, thus it cannot |
|
* be removed from the page cache and replaced by a new |
|
* page before mmu_notifier_invalidate_range_end, so no |
|
* concurrent thread might update its page table to |
|
* point at new page while a device still is using this |
|
* page. |
|
* |
|
* See Documentation/vm/mmu_notifier.rst |
|
*/ |
|
dec_mm_counter(mm, mm_counter_file(page)); |
|
} |
|
discard: |
|
/* |
|
* No need to call mmu_notifier_invalidate_range() it has be |
|
* done above for all cases requiring it to happen under page |
|
* table lock before mmu_notifier_invalidate_range_end() |
|
* |
|
* See Documentation/vm/mmu_notifier.rst |
|
*/ |
|
page_remove_rmap(subpage, PageHuge(page)); |
|
put_page(page); |
|
} |
|
|
|
mmu_notifier_invalidate_range_end(&range); |
|
|
|
return ret; |
|
} |
|
|
|
static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) |
|
{ |
|
return vma_is_temporary_stack(vma); |
|
} |
|
|
|
static int page_not_mapped(struct page *page) |
|
{ |
|
return !page_mapped(page); |
|
} |
|
|
|
/** |
|
* try_to_unmap - try to remove all page table mappings to a page |
|
* @page: the page to get unmapped |
|
* @flags: action and flags |
|
* |
|
* Tries to remove all the page table entries which are mapping this |
|
* page, used in the pageout path. Caller must hold the page lock. |
|
* |
|
* If unmap is successful, return true. Otherwise, false. |
|
*/ |
|
bool try_to_unmap(struct page *page, enum ttu_flags flags) |
|
{ |
|
struct rmap_walk_control rwc = { |
|
.rmap_one = try_to_unmap_one, |
|
.arg = (void *)flags, |
|
.done = page_not_mapped, |
|
.anon_lock = page_lock_anon_vma_read, |
|
}; |
|
|
|
/* |
|
* During exec, a temporary VMA is setup and later moved. |
|
* The VMA is moved under the anon_vma lock but not the |
|
* page tables leading to a race where migration cannot |
|
* find the migration ptes. Rather than increasing the |
|
* locking requirements of exec(), migration skips |
|
* temporary VMAs until after exec() completes. |
|
*/ |
|
if ((flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE)) |
|
&& !PageKsm(page) && PageAnon(page)) |
|
rwc.invalid_vma = invalid_migration_vma; |
|
|
|
if (flags & TTU_RMAP_LOCKED) |
|
rmap_walk_locked(page, &rwc); |
|
else |
|
rmap_walk(page, &rwc); |
|
|
|
return !page_mapcount(page) ? true : false; |
|
} |
|
|
|
/** |
|
* try_to_munlock - try to munlock a page |
|
* @page: the page to be munlocked |
|
* |
|
* Called from munlock code. Checks all of the VMAs mapping the page |
|
* to make sure nobody else has this page mlocked. The page will be |
|
* returned with PG_mlocked cleared if no other vmas have it mlocked. |
|
*/ |
|
|
|
void try_to_munlock(struct page *page) |
|
{ |
|
struct rmap_walk_control rwc = { |
|
.rmap_one = try_to_unmap_one, |
|
.arg = (void *)TTU_MUNLOCK, |
|
.done = page_not_mapped, |
|
.anon_lock = page_lock_anon_vma_read, |
|
|
|
}; |
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page); |
|
VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page); |
|
|
|
rmap_walk(page, &rwc); |
|
} |
|
|
|
void __put_anon_vma(struct anon_vma *anon_vma) |
|
{ |
|
struct anon_vma *root = anon_vma->root; |
|
|
|
anon_vma_free(anon_vma); |
|
if (root != anon_vma && atomic_dec_and_test(&root->refcount)) |
|
anon_vma_free(root); |
|
} |
|
|
|
static struct anon_vma *rmap_walk_anon_lock(struct page *page, |
|
struct rmap_walk_control *rwc) |
|
{ |
|
struct anon_vma *anon_vma; |
|
|
|
if (rwc->anon_lock) |
|
return rwc->anon_lock(page); |
|
|
|
/* |
|
* Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() |
|
* because that depends on page_mapped(); but not all its usages |
|
* are holding mmap_lock. Users without mmap_lock are required to |
|
* take a reference count to prevent the anon_vma disappearing |
|
*/ |
|
anon_vma = page_anon_vma(page); |
|
if (!anon_vma) |
|
return NULL; |
|
|
|
anon_vma_lock_read(anon_vma); |
|
return anon_vma; |
|
} |
|
|
|
/* |
|
* rmap_walk_anon - do something to anonymous page using the object-based |
|
* rmap method |
|
* @page: the page to be handled |
|
* @rwc: control variable according to each walk type |
|
* |
|
* Find all the mappings of a page using the mapping pointer and the vma chains |
|
* contained in the anon_vma struct it points to. |
|
* |
|
* When called from try_to_munlock(), the mmap_lock of the mm containing the vma |
|
* where the page was found will be held for write. So, we won't recheck |
|
* vm_flags for that VMA. That should be OK, because that vma shouldn't be |
|
* LOCKED. |
|
*/ |
|
static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc, |
|
bool locked) |
|
{ |
|
struct anon_vma *anon_vma; |
|
pgoff_t pgoff_start, pgoff_end; |
|
struct anon_vma_chain *avc; |
|
|
|
if (locked) { |
|
anon_vma = page_anon_vma(page); |
|
/* anon_vma disappear under us? */ |
|
VM_BUG_ON_PAGE(!anon_vma, page); |
|
} else { |
|
anon_vma = rmap_walk_anon_lock(page, rwc); |
|
} |
|
if (!anon_vma) |
|
return; |
|
|
|
pgoff_start = page_to_pgoff(page); |
|
pgoff_end = pgoff_start + thp_nr_pages(page) - 1; |
|
anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, |
|
pgoff_start, pgoff_end) { |
|
struct vm_area_struct *vma = avc->vma; |
|
unsigned long address = vma_address(page, vma); |
|
|
|
cond_resched(); |
|
|
|
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) |
|
continue; |
|
|
|
if (!rwc->rmap_one(page, vma, address, rwc->arg)) |
|
break; |
|
if (rwc->done && rwc->done(page)) |
|
break; |
|
} |
|
|
|
if (!locked) |
|
anon_vma_unlock_read(anon_vma); |
|
} |
|
|
|
/* |
|
* rmap_walk_file - do something to file page using the object-based rmap method |
|
* @page: the page to be handled |
|
* @rwc: control variable according to each walk type |
|
* |
|
* Find all the mappings of a page using the mapping pointer and the vma chains |
|
* contained in the address_space struct it points to. |
|
* |
|
* When called from try_to_munlock(), the mmap_lock of the mm containing the vma |
|
* where the page was found will be held for write. So, we won't recheck |
|
* vm_flags for that VMA. That should be OK, because that vma shouldn't be |
|
* LOCKED. |
|
*/ |
|
static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc, |
|
bool locked) |
|
{ |
|
struct address_space *mapping = page_mapping(page); |
|
pgoff_t pgoff_start, pgoff_end; |
|
struct vm_area_struct *vma; |
|
|
|
/* |
|
* The page lock not only makes sure that page->mapping cannot |
|
* suddenly be NULLified by truncation, it makes sure that the |
|
* structure at mapping cannot be freed and reused yet, |
|
* so we can safely take mapping->i_mmap_rwsem. |
|
*/ |
|
VM_BUG_ON_PAGE(!PageLocked(page), page); |
|
|
|
if (!mapping) |
|
return; |
|
|
|
pgoff_start = page_to_pgoff(page); |
|
pgoff_end = pgoff_start + thp_nr_pages(page) - 1; |
|
if (!locked) |
|
i_mmap_lock_read(mapping); |
|
vma_interval_tree_foreach(vma, &mapping->i_mmap, |
|
pgoff_start, pgoff_end) { |
|
unsigned long address = vma_address(page, vma); |
|
|
|
cond_resched(); |
|
|
|
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) |
|
continue; |
|
|
|
if (!rwc->rmap_one(page, vma, address, rwc->arg)) |
|
goto done; |
|
if (rwc->done && rwc->done(page)) |
|
goto done; |
|
} |
|
|
|
done: |
|
if (!locked) |
|
i_mmap_unlock_read(mapping); |
|
} |
|
|
|
void rmap_walk(struct page *page, struct rmap_walk_control *rwc) |
|
{ |
|
if (unlikely(PageKsm(page))) |
|
rmap_walk_ksm(page, rwc); |
|
else if (PageAnon(page)) |
|
rmap_walk_anon(page, rwc, false); |
|
else |
|
rmap_walk_file(page, rwc, false); |
|
} |
|
|
|
/* Like rmap_walk, but caller holds relevant rmap lock */ |
|
void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) |
|
{ |
|
/* no ksm support for now */ |
|
VM_BUG_ON_PAGE(PageKsm(page), page); |
|
if (PageAnon(page)) |
|
rmap_walk_anon(page, rwc, true); |
|
else |
|
rmap_walk_file(page, rwc, true); |
|
} |
|
|
|
#ifdef CONFIG_HUGETLB_PAGE |
|
/* |
|
* The following two functions are for anonymous (private mapped) hugepages. |
|
* Unlike common anonymous pages, anonymous hugepages have no accounting code |
|
* and no lru code, because we handle hugepages differently from common pages. |
|
*/ |
|
void hugepage_add_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address) |
|
{ |
|
struct anon_vma *anon_vma = vma->anon_vma; |
|
int first; |
|
|
|
BUG_ON(!PageLocked(page)); |
|
BUG_ON(!anon_vma); |
|
/* address might be in next vma when migration races vma_adjust */ |
|
first = atomic_inc_and_test(compound_mapcount_ptr(page)); |
|
if (first) |
|
__page_set_anon_rmap(page, vma, address, 0); |
|
} |
|
|
|
void hugepage_add_new_anon_rmap(struct page *page, |
|
struct vm_area_struct *vma, unsigned long address) |
|
{ |
|
BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
|
atomic_set(compound_mapcount_ptr(page), 0); |
|
if (hpage_pincount_available(page)) |
|
atomic_set(compound_pincount_ptr(page), 0); |
|
|
|
__page_set_anon_rmap(page, vma, address, 1); |
|
} |
|
#endif /* CONFIG_HUGETLB_PAGE */
|
|
|