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776 lines
19 KiB
776 lines
19 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/mm/mlock.c |
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* |
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* (C) Copyright 1995 Linus Torvalds |
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* (C) Copyright 2002 Christoph Hellwig |
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*/ |
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|
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#include <linux/capability.h> |
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#include <linux/mman.h> |
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#include <linux/mm.h> |
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#include <linux/sched/user.h> |
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#include <linux/swap.h> |
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#include <linux/swapops.h> |
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#include <linux/pagemap.h> |
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#include <linux/pagevec.h> |
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#include <linux/pagewalk.h> |
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#include <linux/mempolicy.h> |
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#include <linux/syscalls.h> |
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#include <linux/sched.h> |
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#include <linux/export.h> |
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#include <linux/rmap.h> |
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#include <linux/mmzone.h> |
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#include <linux/hugetlb.h> |
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#include <linux/memcontrol.h> |
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#include <linux/mm_inline.h> |
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#include <linux/secretmem.h> |
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#include "internal.h" |
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struct mlock_pvec { |
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local_lock_t lock; |
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struct pagevec vec; |
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}; |
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static DEFINE_PER_CPU(struct mlock_pvec, mlock_pvec) = { |
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.lock = INIT_LOCAL_LOCK(lock), |
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}; |
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bool can_do_mlock(void) |
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{ |
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if (rlimit(RLIMIT_MEMLOCK) != 0) |
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return true; |
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if (capable(CAP_IPC_LOCK)) |
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return true; |
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return false; |
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} |
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EXPORT_SYMBOL(can_do_mlock); |
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|
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/* |
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* Mlocked pages are marked with PageMlocked() flag for efficient testing |
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* in vmscan and, possibly, the fault path; and to support semi-accurate |
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* statistics. |
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* |
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* An mlocked page [PageMlocked(page)] is unevictable. As such, it will |
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* be placed on the LRU "unevictable" list, rather than the [in]active lists. |
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* The unevictable list is an LRU sibling list to the [in]active lists. |
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* PageUnevictable is set to indicate the unevictable state. |
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*/ |
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|
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static struct lruvec *__mlock_page(struct page *page, struct lruvec *lruvec) |
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{ |
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/* There is nothing more we can do while it's off LRU */ |
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if (!TestClearPageLRU(page)) |
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return lruvec; |
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lruvec = folio_lruvec_relock_irq(page_folio(page), lruvec); |
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if (unlikely(page_evictable(page))) { |
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/* |
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* This is a little surprising, but quite possible: |
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* PageMlocked must have got cleared already by another CPU. |
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* Could this page be on the Unevictable LRU? I'm not sure, |
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* but move it now if so. |
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*/ |
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if (PageUnevictable(page)) { |
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del_page_from_lru_list(page, lruvec); |
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ClearPageUnevictable(page); |
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add_page_to_lru_list(page, lruvec); |
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__count_vm_events(UNEVICTABLE_PGRESCUED, |
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thp_nr_pages(page)); |
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} |
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goto out; |
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} |
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if (PageUnevictable(page)) { |
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if (PageMlocked(page)) |
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page->mlock_count++; |
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goto out; |
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} |
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del_page_from_lru_list(page, lruvec); |
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ClearPageActive(page); |
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SetPageUnevictable(page); |
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page->mlock_count = !!PageMlocked(page); |
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add_page_to_lru_list(page, lruvec); |
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__count_vm_events(UNEVICTABLE_PGCULLED, thp_nr_pages(page)); |
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out: |
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SetPageLRU(page); |
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return lruvec; |
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} |
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static struct lruvec *__mlock_new_page(struct page *page, struct lruvec *lruvec) |
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{ |
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VM_BUG_ON_PAGE(PageLRU(page), page); |
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lruvec = folio_lruvec_relock_irq(page_folio(page), lruvec); |
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/* As above, this is a little surprising, but possible */ |
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if (unlikely(page_evictable(page))) |
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goto out; |
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SetPageUnevictable(page); |
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page->mlock_count = !!PageMlocked(page); |
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__count_vm_events(UNEVICTABLE_PGCULLED, thp_nr_pages(page)); |
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out: |
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add_page_to_lru_list(page, lruvec); |
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SetPageLRU(page); |
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return lruvec; |
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} |
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static struct lruvec *__munlock_page(struct page *page, struct lruvec *lruvec) |
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{ |
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int nr_pages = thp_nr_pages(page); |
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bool isolated = false; |
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if (!TestClearPageLRU(page)) |
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goto munlock; |
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isolated = true; |
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lruvec = folio_lruvec_relock_irq(page_folio(page), lruvec); |
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if (PageUnevictable(page)) { |
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/* Then mlock_count is maintained, but might undercount */ |
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if (page->mlock_count) |
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page->mlock_count--; |
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if (page->mlock_count) |
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goto out; |
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} |
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/* else assume that was the last mlock: reclaim will fix it if not */ |
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munlock: |
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if (TestClearPageMlocked(page)) { |
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__mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); |
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if (isolated || !PageUnevictable(page)) |
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__count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages); |
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else |
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__count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages); |
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} |
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/* page_evictable() has to be checked *after* clearing Mlocked */ |
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if (isolated && PageUnevictable(page) && page_evictable(page)) { |
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del_page_from_lru_list(page, lruvec); |
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ClearPageUnevictable(page); |
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add_page_to_lru_list(page, lruvec); |
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__count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages); |
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} |
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out: |
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if (isolated) |
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SetPageLRU(page); |
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return lruvec; |
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} |
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/* |
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* Flags held in the low bits of a struct page pointer on the mlock_pvec. |
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*/ |
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#define LRU_PAGE 0x1 |
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#define NEW_PAGE 0x2 |
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static inline struct page *mlock_lru(struct page *page) |
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{ |
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return (struct page *)((unsigned long)page + LRU_PAGE); |
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} |
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static inline struct page *mlock_new(struct page *page) |
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{ |
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return (struct page *)((unsigned long)page + NEW_PAGE); |
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} |
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/* |
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* mlock_pagevec() is derived from pagevec_lru_move_fn(): |
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* perhaps that can make use of such page pointer flags in future, |
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* but for now just keep it for mlock. We could use three separate |
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* pagevecs instead, but one feels better (munlocking a full pagevec |
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* does not need to drain mlocking pagevecs first). |
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*/ |
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static void mlock_pagevec(struct pagevec *pvec) |
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{ |
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struct lruvec *lruvec = NULL; |
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unsigned long mlock; |
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struct page *page; |
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int i; |
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for (i = 0; i < pagevec_count(pvec); i++) { |
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page = pvec->pages[i]; |
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mlock = (unsigned long)page & (LRU_PAGE | NEW_PAGE); |
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page = (struct page *)((unsigned long)page - mlock); |
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pvec->pages[i] = page; |
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if (mlock & LRU_PAGE) |
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lruvec = __mlock_page(page, lruvec); |
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else if (mlock & NEW_PAGE) |
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lruvec = __mlock_new_page(page, lruvec); |
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else |
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lruvec = __munlock_page(page, lruvec); |
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} |
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if (lruvec) |
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unlock_page_lruvec_irq(lruvec); |
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release_pages(pvec->pages, pvec->nr); |
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pagevec_reinit(pvec); |
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} |
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void mlock_page_drain_local(void) |
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{ |
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struct pagevec *pvec; |
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local_lock(&mlock_pvec.lock); |
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pvec = this_cpu_ptr(&mlock_pvec.vec); |
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if (pagevec_count(pvec)) |
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mlock_pagevec(pvec); |
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local_unlock(&mlock_pvec.lock); |
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} |
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void mlock_page_drain_remote(int cpu) |
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{ |
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struct pagevec *pvec; |
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WARN_ON_ONCE(cpu_online(cpu)); |
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pvec = &per_cpu(mlock_pvec.vec, cpu); |
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if (pagevec_count(pvec)) |
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mlock_pagevec(pvec); |
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} |
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bool need_mlock_page_drain(int cpu) |
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{ |
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return pagevec_count(&per_cpu(mlock_pvec.vec, cpu)); |
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} |
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/** |
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* mlock_folio - mlock a folio already on (or temporarily off) LRU |
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* @folio: folio to be mlocked. |
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*/ |
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void mlock_folio(struct folio *folio) |
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{ |
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struct pagevec *pvec; |
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local_lock(&mlock_pvec.lock); |
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pvec = this_cpu_ptr(&mlock_pvec.vec); |
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if (!folio_test_set_mlocked(folio)) { |
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int nr_pages = folio_nr_pages(folio); |
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zone_stat_mod_folio(folio, NR_MLOCK, nr_pages); |
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__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); |
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} |
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folio_get(folio); |
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if (!pagevec_add(pvec, mlock_lru(&folio->page)) || |
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folio_test_large(folio) || lru_cache_disabled()) |
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mlock_pagevec(pvec); |
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local_unlock(&mlock_pvec.lock); |
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} |
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/** |
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* mlock_new_page - mlock a newly allocated page not yet on LRU |
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* @page: page to be mlocked, either a normal page or a THP head. |
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*/ |
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void mlock_new_page(struct page *page) |
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{ |
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struct pagevec *pvec; |
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int nr_pages = thp_nr_pages(page); |
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local_lock(&mlock_pvec.lock); |
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pvec = this_cpu_ptr(&mlock_pvec.vec); |
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SetPageMlocked(page); |
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mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages); |
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__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); |
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get_page(page); |
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if (!pagevec_add(pvec, mlock_new(page)) || |
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PageHead(page) || lru_cache_disabled()) |
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mlock_pagevec(pvec); |
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local_unlock(&mlock_pvec.lock); |
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} |
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/** |
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* munlock_page - munlock a page |
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* @page: page to be munlocked, either a normal page or a THP head. |
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*/ |
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void munlock_page(struct page *page) |
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{ |
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struct pagevec *pvec; |
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local_lock(&mlock_pvec.lock); |
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pvec = this_cpu_ptr(&mlock_pvec.vec); |
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/* |
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* TestClearPageMlocked(page) must be left to __munlock_page(), |
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* which will check whether the page is multiply mlocked. |
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*/ |
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get_page(page); |
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if (!pagevec_add(pvec, page) || |
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PageHead(page) || lru_cache_disabled()) |
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mlock_pagevec(pvec); |
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local_unlock(&mlock_pvec.lock); |
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} |
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static int mlock_pte_range(pmd_t *pmd, unsigned long addr, |
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unsigned long end, struct mm_walk *walk) |
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{ |
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struct vm_area_struct *vma = walk->vma; |
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spinlock_t *ptl; |
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pte_t *start_pte, *pte; |
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struct page *page; |
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ptl = pmd_trans_huge_lock(pmd, vma); |
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if (ptl) { |
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if (!pmd_present(*pmd)) |
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goto out; |
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if (is_huge_zero_pmd(*pmd)) |
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goto out; |
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page = pmd_page(*pmd); |
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if (vma->vm_flags & VM_LOCKED) |
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mlock_folio(page_folio(page)); |
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else |
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munlock_page(page); |
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goto out; |
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} |
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start_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
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for (pte = start_pte; addr != end; pte++, addr += PAGE_SIZE) { |
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if (!pte_present(*pte)) |
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continue; |
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page = vm_normal_page(vma, addr, *pte); |
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if (!page || is_zone_device_page(page)) |
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continue; |
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if (PageTransCompound(page)) |
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continue; |
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if (vma->vm_flags & VM_LOCKED) |
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mlock_folio(page_folio(page)); |
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else |
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munlock_page(page); |
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} |
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pte_unmap(start_pte); |
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out: |
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spin_unlock(ptl); |
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cond_resched(); |
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return 0; |
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} |
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/* |
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* mlock_vma_pages_range() - mlock any pages already in the range, |
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* or munlock all pages in the range. |
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* @vma - vma containing range to be mlock()ed or munlock()ed |
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* @start - start address in @vma of the range |
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* @end - end of range in @vma |
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* @newflags - the new set of flags for @vma. |
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* |
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* Called for mlock(), mlock2() and mlockall(), to set @vma VM_LOCKED; |
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* called for munlock() and munlockall(), to clear VM_LOCKED from @vma. |
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*/ |
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static void mlock_vma_pages_range(struct vm_area_struct *vma, |
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unsigned long start, unsigned long end, vm_flags_t newflags) |
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{ |
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static const struct mm_walk_ops mlock_walk_ops = { |
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.pmd_entry = mlock_pte_range, |
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}; |
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/* |
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* There is a slight chance that concurrent page migration, |
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* or page reclaim finding a page of this now-VM_LOCKED vma, |
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* will call mlock_vma_page() and raise page's mlock_count: |
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* double counting, leaving the page unevictable indefinitely. |
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* Communicate this danger to mlock_vma_page() with VM_IO, |
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* which is a VM_SPECIAL flag not allowed on VM_LOCKED vmas. |
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* mmap_lock is held in write mode here, so this weird |
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* combination should not be visible to other mmap_lock users; |
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* but WRITE_ONCE so rmap walkers must see VM_IO if VM_LOCKED. |
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*/ |
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if (newflags & VM_LOCKED) |
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newflags |= VM_IO; |
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WRITE_ONCE(vma->vm_flags, newflags); |
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lru_add_drain(); |
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walk_page_range(vma->vm_mm, start, end, &mlock_walk_ops, NULL); |
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lru_add_drain(); |
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if (newflags & VM_IO) { |
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newflags &= ~VM_IO; |
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WRITE_ONCE(vma->vm_flags, newflags); |
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} |
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} |
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/* |
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* mlock_fixup - handle mlock[all]/munlock[all] requests. |
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* |
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* Filters out "special" vmas -- VM_LOCKED never gets set for these, and |
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* munlock is a no-op. However, for some special vmas, we go ahead and |
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* populate the ptes. |
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* |
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* For vmas that pass the filters, merge/split as appropriate. |
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*/ |
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static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev, |
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unsigned long start, unsigned long end, vm_flags_t newflags) |
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{ |
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struct mm_struct *mm = vma->vm_mm; |
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pgoff_t pgoff; |
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int nr_pages; |
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int ret = 0; |
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vm_flags_t oldflags = vma->vm_flags; |
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if (newflags == oldflags || (oldflags & VM_SPECIAL) || |
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is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) || |
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vma_is_dax(vma) || vma_is_secretmem(vma)) |
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/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */ |
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goto out; |
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pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); |
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*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma, |
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vma->vm_file, pgoff, vma_policy(vma), |
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vma->vm_userfaultfd_ctx, anon_vma_name(vma)); |
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if (*prev) { |
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vma = *prev; |
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goto success; |
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} |
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if (start != vma->vm_start) { |
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ret = split_vma(mm, vma, start, 1); |
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if (ret) |
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goto out; |
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} |
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if (end != vma->vm_end) { |
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ret = split_vma(mm, vma, end, 0); |
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if (ret) |
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goto out; |
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} |
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success: |
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/* |
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* Keep track of amount of locked VM. |
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*/ |
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nr_pages = (end - start) >> PAGE_SHIFT; |
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if (!(newflags & VM_LOCKED)) |
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nr_pages = -nr_pages; |
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else if (oldflags & VM_LOCKED) |
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nr_pages = 0; |
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mm->locked_vm += nr_pages; |
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|
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/* |
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* vm_flags is protected by the mmap_lock held in write mode. |
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* It's okay if try_to_unmap_one unmaps a page just after we |
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* set VM_LOCKED, populate_vma_page_range will bring it back. |
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*/ |
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if ((newflags & VM_LOCKED) && (oldflags & VM_LOCKED)) { |
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/* No work to do, and mlocking twice would be wrong */ |
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vma->vm_flags = newflags; |
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} else { |
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mlock_vma_pages_range(vma, start, end, newflags); |
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} |
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out: |
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*prev = vma; |
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return ret; |
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} |
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|
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static int apply_vma_lock_flags(unsigned long start, size_t len, |
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vm_flags_t flags) |
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{ |
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unsigned long nstart, end, tmp; |
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struct vm_area_struct *vma, *prev; |
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int error; |
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VM_BUG_ON(offset_in_page(start)); |
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VM_BUG_ON(len != PAGE_ALIGN(len)); |
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end = start + len; |
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if (end < start) |
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return -EINVAL; |
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if (end == start) |
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return 0; |
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vma = find_vma(current->mm, start); |
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if (!vma || vma->vm_start > start) |
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return -ENOMEM; |
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prev = vma->vm_prev; |
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if (start > vma->vm_start) |
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prev = vma; |
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|
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for (nstart = start ; ; ) { |
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vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK; |
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newflags |= flags; |
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/* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
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tmp = vma->vm_end; |
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if (tmp > end) |
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tmp = end; |
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error = mlock_fixup(vma, &prev, nstart, tmp, newflags); |
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if (error) |
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break; |
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nstart = tmp; |
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if (nstart < prev->vm_end) |
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nstart = prev->vm_end; |
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if (nstart >= end) |
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break; |
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vma = prev->vm_next; |
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if (!vma || vma->vm_start != nstart) { |
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error = -ENOMEM; |
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break; |
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} |
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} |
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return error; |
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} |
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|
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/* |
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* Go through vma areas and sum size of mlocked |
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* vma pages, as return value. |
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* Note deferred memory locking case(mlock2(,,MLOCK_ONFAULT) |
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* is also counted. |
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* Return value: previously mlocked page counts |
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*/ |
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static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm, |
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unsigned long start, size_t len) |
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{ |
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struct vm_area_struct *vma; |
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unsigned long count = 0; |
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|
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if (mm == NULL) |
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mm = current->mm; |
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|
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vma = find_vma(mm, start); |
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if (vma == NULL) |
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return 0; |
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|
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for (; vma ; vma = vma->vm_next) { |
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if (start >= vma->vm_end) |
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continue; |
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if (start + len <= vma->vm_start) |
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break; |
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if (vma->vm_flags & VM_LOCKED) { |
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if (start > vma->vm_start) |
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count -= (start - vma->vm_start); |
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if (start + len < vma->vm_end) { |
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count += start + len - vma->vm_start; |
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break; |
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} |
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count += vma->vm_end - vma->vm_start; |
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} |
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} |
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|
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return count >> PAGE_SHIFT; |
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} |
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|
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/* |
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* convert get_user_pages() return value to posix mlock() error |
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*/ |
|
static int __mlock_posix_error_return(long retval) |
|
{ |
|
if (retval == -EFAULT) |
|
retval = -ENOMEM; |
|
else if (retval == -ENOMEM) |
|
retval = -EAGAIN; |
|
return retval; |
|
} |
|
|
|
static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t flags) |
|
{ |
|
unsigned long locked; |
|
unsigned long lock_limit; |
|
int error = -ENOMEM; |
|
|
|
start = untagged_addr(start); |
|
|
|
if (!can_do_mlock()) |
|
return -EPERM; |
|
|
|
len = PAGE_ALIGN(len + (offset_in_page(start))); |
|
start &= PAGE_MASK; |
|
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK); |
|
lock_limit >>= PAGE_SHIFT; |
|
locked = len >> PAGE_SHIFT; |
|
|
|
if (mmap_write_lock_killable(current->mm)) |
|
return -EINTR; |
|
|
|
locked += current->mm->locked_vm; |
|
if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) { |
|
/* |
|
* It is possible that the regions requested intersect with |
|
* previously mlocked areas, that part area in "mm->locked_vm" |
|
* should not be counted to new mlock increment count. So check |
|
* and adjust locked count if necessary. |
|
*/ |
|
locked -= count_mm_mlocked_page_nr(current->mm, |
|
start, len); |
|
} |
|
|
|
/* check against resource limits */ |
|
if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) |
|
error = apply_vma_lock_flags(start, len, flags); |
|
|
|
mmap_write_unlock(current->mm); |
|
if (error) |
|
return error; |
|
|
|
error = __mm_populate(start, len, 0); |
|
if (error) |
|
return __mlock_posix_error_return(error); |
|
return 0; |
|
} |
|
|
|
SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) |
|
{ |
|
return do_mlock(start, len, VM_LOCKED); |
|
} |
|
|
|
SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags) |
|
{ |
|
vm_flags_t vm_flags = VM_LOCKED; |
|
|
|
if (flags & ~MLOCK_ONFAULT) |
|
return -EINVAL; |
|
|
|
if (flags & MLOCK_ONFAULT) |
|
vm_flags |= VM_LOCKONFAULT; |
|
|
|
return do_mlock(start, len, vm_flags); |
|
} |
|
|
|
SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) |
|
{ |
|
int ret; |
|
|
|
start = untagged_addr(start); |
|
|
|
len = PAGE_ALIGN(len + (offset_in_page(start))); |
|
start &= PAGE_MASK; |
|
|
|
if (mmap_write_lock_killable(current->mm)) |
|
return -EINTR; |
|
ret = apply_vma_lock_flags(start, len, 0); |
|
mmap_write_unlock(current->mm); |
|
|
|
return ret; |
|
} |
|
|
|
/* |
|
* Take the MCL_* flags passed into mlockall (or 0 if called from munlockall) |
|
* and translate into the appropriate modifications to mm->def_flags and/or the |
|
* flags for all current VMAs. |
|
* |
|
* There are a couple of subtleties with this. If mlockall() is called multiple |
|
* times with different flags, the values do not necessarily stack. If mlockall |
|
* is called once including the MCL_FUTURE flag and then a second time without |
|
* it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags. |
|
*/ |
|
static int apply_mlockall_flags(int flags) |
|
{ |
|
struct vm_area_struct *vma, *prev = NULL; |
|
vm_flags_t to_add = 0; |
|
|
|
current->mm->def_flags &= VM_LOCKED_CLEAR_MASK; |
|
if (flags & MCL_FUTURE) { |
|
current->mm->def_flags |= VM_LOCKED; |
|
|
|
if (flags & MCL_ONFAULT) |
|
current->mm->def_flags |= VM_LOCKONFAULT; |
|
|
|
if (!(flags & MCL_CURRENT)) |
|
goto out; |
|
} |
|
|
|
if (flags & MCL_CURRENT) { |
|
to_add |= VM_LOCKED; |
|
if (flags & MCL_ONFAULT) |
|
to_add |= VM_LOCKONFAULT; |
|
} |
|
|
|
for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { |
|
vm_flags_t newflags; |
|
|
|
newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK; |
|
newflags |= to_add; |
|
|
|
/* Ignore errors */ |
|
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); |
|
cond_resched(); |
|
} |
|
out: |
|
return 0; |
|
} |
|
|
|
SYSCALL_DEFINE1(mlockall, int, flags) |
|
{ |
|
unsigned long lock_limit; |
|
int ret; |
|
|
|
if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) || |
|
flags == MCL_ONFAULT) |
|
return -EINVAL; |
|
|
|
if (!can_do_mlock()) |
|
return -EPERM; |
|
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK); |
|
lock_limit >>= PAGE_SHIFT; |
|
|
|
if (mmap_write_lock_killable(current->mm)) |
|
return -EINTR; |
|
|
|
ret = -ENOMEM; |
|
if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || |
|
capable(CAP_IPC_LOCK)) |
|
ret = apply_mlockall_flags(flags); |
|
mmap_write_unlock(current->mm); |
|
if (!ret && (flags & MCL_CURRENT)) |
|
mm_populate(0, TASK_SIZE); |
|
|
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE0(munlockall) |
|
{ |
|
int ret; |
|
|
|
if (mmap_write_lock_killable(current->mm)) |
|
return -EINTR; |
|
ret = apply_mlockall_flags(0); |
|
mmap_write_unlock(current->mm); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB |
|
* shm segments) get accounted against the user_struct instead. |
|
*/ |
|
static DEFINE_SPINLOCK(shmlock_user_lock); |
|
|
|
int user_shm_lock(size_t size, struct ucounts *ucounts) |
|
{ |
|
unsigned long lock_limit, locked; |
|
long memlock; |
|
int allowed = 0; |
|
|
|
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
|
lock_limit = rlimit(RLIMIT_MEMLOCK); |
|
if (lock_limit != RLIM_INFINITY) |
|
lock_limit >>= PAGE_SHIFT; |
|
spin_lock(&shmlock_user_lock); |
|
memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); |
|
|
|
if ((memlock == LONG_MAX || memlock > lock_limit) && !capable(CAP_IPC_LOCK)) { |
|
dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); |
|
goto out; |
|
} |
|
if (!get_ucounts(ucounts)) { |
|
dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); |
|
allowed = 0; |
|
goto out; |
|
} |
|
allowed = 1; |
|
out: |
|
spin_unlock(&shmlock_user_lock); |
|
return allowed; |
|
} |
|
|
|
void user_shm_unlock(size_t size, struct ucounts *ucounts) |
|
{ |
|
spin_lock(&shmlock_user_lock); |
|
dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT); |
|
spin_unlock(&shmlock_user_lock); |
|
put_ucounts(ucounts); |
|
}
|
|
|