874 lines
23 KiB
C
874 lines
23 KiB
C
// 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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#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/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 "internal.h"
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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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* 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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* When lazy mlocking via vmscan, it is important to ensure that the
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* vma's VM_LOCKED status is not concurrently being modified, otherwise we
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* may have mlocked a page that is being munlocked. So lazy mlock must take
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* the mmap_sem for read, and verify that the vma really is locked
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* (see mm/rmap.c).
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*/
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/*
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* LRU accounting for clear_page_mlock()
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*/
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void clear_page_mlock(struct page *page)
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{
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if (!TestClearPageMlocked(page))
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return;
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mod_zone_page_state(page_zone(page), NR_MLOCK,
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-hpage_nr_pages(page));
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count_vm_event(UNEVICTABLE_PGCLEARED);
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/*
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* The previous TestClearPageMlocked() corresponds to the smp_mb()
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* in __pagevec_lru_add_fn().
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*
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* See __pagevec_lru_add_fn for more explanation.
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*/
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if (!isolate_lru_page(page)) {
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putback_lru_page(page);
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} else {
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/*
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* We lost the race. the page already moved to evictable list.
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*/
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if (PageUnevictable(page))
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count_vm_event(UNEVICTABLE_PGSTRANDED);
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}
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}
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/*
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* Mark page as mlocked if not already.
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* If page on LRU, isolate and putback to move to unevictable list.
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*/
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void mlock_vma_page(struct page *page)
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{
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/* Serialize with page migration */
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BUG_ON(!PageLocked(page));
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VM_BUG_ON_PAGE(PageTail(page), page);
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VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
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if (!TestSetPageMlocked(page)) {
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mod_zone_page_state(page_zone(page), NR_MLOCK,
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hpage_nr_pages(page));
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count_vm_event(UNEVICTABLE_PGMLOCKED);
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if (!isolate_lru_page(page))
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putback_lru_page(page);
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}
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}
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/*
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* Isolate a page from LRU with optional get_page() pin.
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* Assumes lru_lock already held and page already pinned.
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*/
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static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
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{
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if (PageLRU(page)) {
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struct lruvec *lruvec;
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lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
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if (getpage)
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get_page(page);
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ClearPageLRU(page);
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del_page_from_lru_list(page, lruvec, page_lru(page));
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return true;
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}
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return false;
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}
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/*
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* Finish munlock after successful page isolation
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*
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* Page must be locked. This is a wrapper for try_to_munlock()
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* and putback_lru_page() with munlock accounting.
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*/
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static void __munlock_isolated_page(struct page *page)
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{
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/*
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* Optimization: if the page was mapped just once, that's our mapping
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* and we don't need to check all the other vmas.
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*/
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if (page_mapcount(page) > 1)
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try_to_munlock(page);
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/* Did try_to_unlock() succeed or punt? */
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if (!PageMlocked(page))
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count_vm_event(UNEVICTABLE_PGMUNLOCKED);
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putback_lru_page(page);
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}
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/*
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* Accounting for page isolation fail during munlock
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*
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* Performs accounting when page isolation fails in munlock. There is nothing
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* else to do because it means some other task has already removed the page
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* from the LRU. putback_lru_page() will take care of removing the page from
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* the unevictable list, if necessary. vmscan [page_referenced()] will move
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* the page back to the unevictable list if some other vma has it mlocked.
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*/
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static void __munlock_isolation_failed(struct page *page)
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{
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if (PageUnevictable(page))
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__count_vm_event(UNEVICTABLE_PGSTRANDED);
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else
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__count_vm_event(UNEVICTABLE_PGMUNLOCKED);
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}
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/**
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* munlock_vma_page - munlock a vma page
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* @page: page to be unlocked, either a normal page or THP page head
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*
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* returns the size of the page as a page mask (0 for normal page,
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* HPAGE_PMD_NR - 1 for THP head page)
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*
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* called from munlock()/munmap() path with page supposedly on the LRU.
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* When we munlock a page, because the vma where we found the page is being
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* munlock()ed or munmap()ed, we want to check whether other vmas hold the
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* page locked so that we can leave it on the unevictable lru list and not
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* bother vmscan with it. However, to walk the page's rmap list in
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* try_to_munlock() we must isolate the page from the LRU. If some other
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* task has removed the page from the LRU, we won't be able to do that.
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* So we clear the PageMlocked as we might not get another chance. If we
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* can't isolate the page, we leave it for putback_lru_page() and vmscan
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* [page_referenced()/try_to_unmap()] to deal with.
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*/
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unsigned int munlock_vma_page(struct page *page)
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{
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int nr_pages;
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pg_data_t *pgdat = page_pgdat(page);
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/* For try_to_munlock() and to serialize with page migration */
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BUG_ON(!PageLocked(page));
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VM_BUG_ON_PAGE(PageTail(page), page);
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/*
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* Serialize with any parallel __split_huge_page_refcount() which
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* might otherwise copy PageMlocked to part of the tail pages before
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* we clear it in the head page. It also stabilizes hpage_nr_pages().
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*/
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spin_lock_irq(&pgdat->lru_lock);
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if (!TestClearPageMlocked(page)) {
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/* Potentially, PTE-mapped THP: do not skip the rest PTEs */
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nr_pages = 1;
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goto unlock_out;
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}
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nr_pages = hpage_nr_pages(page);
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__mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
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if (__munlock_isolate_lru_page(page, true)) {
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spin_unlock_irq(&pgdat->lru_lock);
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__munlock_isolated_page(page);
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goto out;
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}
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__munlock_isolation_failed(page);
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unlock_out:
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spin_unlock_irq(&pgdat->lru_lock);
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out:
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return nr_pages - 1;
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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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*/
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static int __mlock_posix_error_return(long retval)
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{
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if (retval == -EFAULT)
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retval = -ENOMEM;
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else if (retval == -ENOMEM)
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retval = -EAGAIN;
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return retval;
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}
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/*
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* Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
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*
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* The fast path is available only for evictable pages with single mapping.
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* Then we can bypass the per-cpu pvec and get better performance.
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* when mapcount > 1 we need try_to_munlock() which can fail.
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* when !page_evictable(), we need the full redo logic of putback_lru_page to
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* avoid leaving evictable page in unevictable list.
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*
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* In case of success, @page is added to @pvec and @pgrescued is incremented
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* in case that the page was previously unevictable. @page is also unlocked.
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*/
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static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec,
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int *pgrescued)
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{
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VM_BUG_ON_PAGE(PageLRU(page), page);
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VM_BUG_ON_PAGE(!PageLocked(page), page);
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if (page_mapcount(page) <= 1 && page_evictable(page)) {
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pagevec_add(pvec, page);
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if (TestClearPageUnevictable(page))
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(*pgrescued)++;
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unlock_page(page);
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return true;
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}
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return false;
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}
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/*
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* Putback multiple evictable pages to the LRU
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*
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* Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
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* the pages might have meanwhile become unevictable but that is OK.
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*/
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static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
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{
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count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
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/*
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*__pagevec_lru_add() calls release_pages() so we don't call
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* put_page() explicitly
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*/
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__pagevec_lru_add(pvec);
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count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
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}
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/*
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* Munlock a batch of pages from the same zone
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*
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* The work is split to two main phases. First phase clears the Mlocked flag
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* and attempts to isolate the pages, all under a single zone lru lock.
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* The second phase finishes the munlock only for pages where isolation
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* succeeded.
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*
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* Note that the pagevec may be modified during the process.
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*/
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static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
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{
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int i;
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int nr = pagevec_count(pvec);
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int delta_munlocked = -nr;
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struct pagevec pvec_putback;
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int pgrescued = 0;
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pagevec_init(&pvec_putback);
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/* Phase 1: page isolation */
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spin_lock_irq(&zone->zone_pgdat->lru_lock);
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for (i = 0; i < nr; i++) {
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struct page *page = pvec->pages[i];
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if (TestClearPageMlocked(page)) {
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/*
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* We already have pin from follow_page_mask()
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* so we can spare the get_page() here.
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*/
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if (__munlock_isolate_lru_page(page, false))
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continue;
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else
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__munlock_isolation_failed(page);
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} else {
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delta_munlocked++;
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}
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/*
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* We won't be munlocking this page in the next phase
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* but we still need to release the follow_page_mask()
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* pin. We cannot do it under lru_lock however. If it's
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* the last pin, __page_cache_release() would deadlock.
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*/
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pagevec_add(&pvec_putback, pvec->pages[i]);
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pvec->pages[i] = NULL;
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}
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__mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
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spin_unlock_irq(&zone->zone_pgdat->lru_lock);
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/* Now we can release pins of pages that we are not munlocking */
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pagevec_release(&pvec_putback);
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/* Phase 2: page munlock */
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for (i = 0; i < nr; i++) {
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struct page *page = pvec->pages[i];
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if (page) {
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lock_page(page);
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if (!__putback_lru_fast_prepare(page, &pvec_putback,
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&pgrescued)) {
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/*
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* Slow path. We don't want to lose the last
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* pin before unlock_page()
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*/
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get_page(page); /* for putback_lru_page() */
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__munlock_isolated_page(page);
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unlock_page(page);
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put_page(page); /* from follow_page_mask() */
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}
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}
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}
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/*
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* Phase 3: page putback for pages that qualified for the fast path
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* This will also call put_page() to return pin from follow_page_mask()
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*/
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if (pagevec_count(&pvec_putback))
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__putback_lru_fast(&pvec_putback, pgrescued);
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}
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/*
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* Fill up pagevec for __munlock_pagevec using pte walk
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*
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* The function expects that the struct page corresponding to @start address is
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* a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
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*
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* The rest of @pvec is filled by subsequent pages within the same pmd and same
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* zone, as long as the pte's are present and vm_normal_page() succeeds. These
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* pages also get pinned.
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*
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* Returns the address of the next page that should be scanned. This equals
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* @start + PAGE_SIZE when no page could be added by the pte walk.
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*/
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static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
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struct vm_area_struct *vma, struct zone *zone,
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unsigned long start, unsigned long end)
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{
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pte_t *pte;
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spinlock_t *ptl;
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/*
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* Initialize pte walk starting at the already pinned page where we
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* are sure that there is a pte, as it was pinned under the same
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* mmap_sem write op.
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*/
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pte = get_locked_pte(vma->vm_mm, start, &ptl);
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/* Make sure we do not cross the page table boundary */
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end = pgd_addr_end(start, end);
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end = p4d_addr_end(start, end);
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end = pud_addr_end(start, end);
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end = pmd_addr_end(start, end);
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/* The page next to the pinned page is the first we will try to get */
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start += PAGE_SIZE;
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while (start < end) {
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struct page *page = NULL;
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pte++;
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if (pte_present(*pte))
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page = vm_normal_page(vma, start, *pte);
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/*
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* Break if page could not be obtained or the page's node+zone does not
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* match
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*/
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if (!page || page_zone(page) != zone)
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break;
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/*
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* Do not use pagevec for PTE-mapped THP,
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* munlock_vma_pages_range() will handle them.
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*/
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if (PageTransCompound(page))
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break;
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get_page(page);
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/*
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* Increase the address that will be returned *before* the
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* eventual break due to pvec becoming full by adding the page
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*/
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start += PAGE_SIZE;
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if (pagevec_add(pvec, page) == 0)
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break;
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}
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pte_unmap_unlock(pte, ptl);
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return start;
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}
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/*
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* munlock_vma_pages_range() - munlock all pages in the vma range.'
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* @vma - vma containing range to be 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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*
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* For mremap(), munmap() and exit().
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*
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* Called with @vma VM_LOCKED.
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*
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* Returns with VM_LOCKED cleared. Callers must be prepared to
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* deal with this.
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*
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* We don't save and restore VM_LOCKED here because pages are
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* still on lru. In unmap path, pages might be scanned by reclaim
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* and re-mlocked by try_to_{munlock|unmap} before we unmap and
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* free them. This will result in freeing mlocked pages.
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*/
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void munlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
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while (start < end) {
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struct page *page;
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unsigned int page_mask = 0;
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unsigned long page_increm;
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struct pagevec pvec;
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struct zone *zone;
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pagevec_init(&pvec);
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/*
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* Although FOLL_DUMP is intended for get_dump_page(),
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* it just so happens that its special treatment of the
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* ZERO_PAGE (returning an error instead of doing get_page)
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* suits munlock very well (and if somehow an abnormal page
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* has sneaked into the range, we won't oops here: great).
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*/
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page = follow_page(vma, start, FOLL_GET | FOLL_DUMP);
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if (page && !IS_ERR(page)) {
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if (PageTransTail(page)) {
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VM_BUG_ON_PAGE(PageMlocked(page), page);
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put_page(page); /* follow_page_mask() */
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} else if (PageTransHuge(page)) {
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lock_page(page);
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/*
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* Any THP page found by follow_page_mask() may
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* have gotten split before reaching
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* munlock_vma_page(), so we need to compute
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* the page_mask here instead.
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*/
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page_mask = munlock_vma_page(page);
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unlock_page(page);
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put_page(page); /* follow_page_mask() */
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} else {
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/*
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* Non-huge pages are handled in batches via
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* pagevec. The pin from follow_page_mask()
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* prevents them from collapsing by THP.
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*/
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pagevec_add(&pvec, page);
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zone = page_zone(page);
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/*
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* Try to fill the rest of pagevec using fast
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* pte walk. This will also update start to
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* the next page to process. Then munlock the
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* pagevec.
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*/
|
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start = __munlock_pagevec_fill(&pvec, vma,
|
|
zone, start, end);
|
|
__munlock_pagevec(&pvec, zone);
|
|
goto next;
|
|
}
|
|
}
|
|
page_increm = 1 + page_mask;
|
|
start += page_increm * PAGE_SIZE;
|
|
next:
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* mlock_fixup - handle mlock[all]/munlock[all] requests.
|
|
*
|
|
* Filters out "special" vmas -- VM_LOCKED never gets set for these, and
|
|
* munlock is a no-op. However, for some special vmas, we go ahead and
|
|
* populate the ptes.
|
|
*
|
|
* For vmas that pass the filters, merge/split as appropriate.
|
|
*/
|
|
static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
|
|
unsigned long start, unsigned long end, vm_flags_t newflags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgoff_t pgoff;
|
|
int nr_pages;
|
|
int ret = 0;
|
|
int lock = !!(newflags & VM_LOCKED);
|
|
vm_flags_t old_flags = vma->vm_flags;
|
|
|
|
if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
|
|
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
|
|
vma_is_dax(vma))
|
|
/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
|
|
goto out;
|
|
|
|
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
|
|
*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
|
|
vma->vm_file, pgoff, vma_policy(vma),
|
|
vma->vm_userfaultfd_ctx);
|
|
if (*prev) {
|
|
vma = *prev;
|
|
goto success;
|
|
}
|
|
|
|
if (start != vma->vm_start) {
|
|
ret = split_vma(mm, vma, start, 1);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
if (end != vma->vm_end) {
|
|
ret = split_vma(mm, vma, end, 0);
|
|
if (ret)
|
|
goto out;
|
|
}
|
|
|
|
success:
|
|
/*
|
|
* Keep track of amount of locked VM.
|
|
*/
|
|
nr_pages = (end - start) >> PAGE_SHIFT;
|
|
if (!lock)
|
|
nr_pages = -nr_pages;
|
|
else if (old_flags & VM_LOCKED)
|
|
nr_pages = 0;
|
|
mm->locked_vm += nr_pages;
|
|
|
|
/*
|
|
* vm_flags is protected by the mmap_sem held in write mode.
|
|
* It's okay if try_to_unmap_one unmaps a page just after we
|
|
* set VM_LOCKED, populate_vma_page_range will bring it back.
|
|
*/
|
|
|
|
if (lock)
|
|
vma->vm_flags = newflags;
|
|
else
|
|
munlock_vma_pages_range(vma, start, end);
|
|
|
|
out:
|
|
*prev = vma;
|
|
return ret;
|
|
}
|
|
|
|
static int apply_vma_lock_flags(unsigned long start, size_t len,
|
|
vm_flags_t flags)
|
|
{
|
|
unsigned long nstart, end, tmp;
|
|
struct vm_area_struct * vma, * prev;
|
|
int error;
|
|
|
|
VM_BUG_ON(offset_in_page(start));
|
|
VM_BUG_ON(len != PAGE_ALIGN(len));
|
|
end = start + len;
|
|
if (end < start)
|
|
return -EINVAL;
|
|
if (end == start)
|
|
return 0;
|
|
vma = find_vma(current->mm, start);
|
|
if (!vma || vma->vm_start > start)
|
|
return -ENOMEM;
|
|
|
|
prev = vma->vm_prev;
|
|
if (start > vma->vm_start)
|
|
prev = vma;
|
|
|
|
for (nstart = start ; ; ) {
|
|
vm_flags_t newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
|
|
|
|
newflags |= flags;
|
|
|
|
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
|
|
tmp = vma->vm_end;
|
|
if (tmp > end)
|
|
tmp = end;
|
|
error = mlock_fixup(vma, &prev, nstart, tmp, newflags);
|
|
if (error)
|
|
break;
|
|
nstart = tmp;
|
|
if (nstart < prev->vm_end)
|
|
nstart = prev->vm_end;
|
|
if (nstart >= end)
|
|
break;
|
|
|
|
vma = prev->vm_next;
|
|
if (!vma || vma->vm_start != nstart) {
|
|
error = -ENOMEM;
|
|
break;
|
|
}
|
|
}
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Go through vma areas and sum size of mlocked
|
|
* vma pages, as return value.
|
|
* Note deferred memory locking case(mlock2(,,MLOCK_ONFAULT)
|
|
* is also counted.
|
|
* Return value: previously mlocked page counts
|
|
*/
|
|
static unsigned long count_mm_mlocked_page_nr(struct mm_struct *mm,
|
|
unsigned long start, size_t len)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long count = 0;
|
|
|
|
if (mm == NULL)
|
|
mm = current->mm;
|
|
|
|
vma = find_vma(mm, start);
|
|
if (vma == NULL)
|
|
vma = mm->mmap;
|
|
|
|
for (; vma ; vma = vma->vm_next) {
|
|
if (start >= vma->vm_end)
|
|
continue;
|
|
if (start + len <= vma->vm_start)
|
|
break;
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
if (start > vma->vm_start)
|
|
count -= (start - vma->vm_start);
|
|
if (start + len < vma->vm_end) {
|
|
count += start + len - vma->vm_start;
|
|
break;
|
|
}
|
|
count += vma->vm_end - vma->vm_start;
|
|
}
|
|
}
|
|
|
|
return count >> PAGE_SHIFT;
|
|
}
|
|
|
|
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 (down_write_killable(¤t->mm->mmap_sem))
|
|
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);
|
|
|
|
up_write(¤t->mm->mmap_sem);
|
|
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 (down_write_killable(¤t->mm->mmap_sem))
|
|
return -EINTR;
|
|
ret = apply_vma_lock_flags(start, len, 0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
|
|
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 (down_write_killable(¤t->mm->mmap_sem))
|
|
return -EINTR;
|
|
|
|
ret = -ENOMEM;
|
|
if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
|
|
capable(CAP_IPC_LOCK))
|
|
ret = apply_mlockall_flags(flags);
|
|
up_write(¤t->mm->mmap_sem);
|
|
if (!ret && (flags & MCL_CURRENT))
|
|
mm_populate(0, TASK_SIZE);
|
|
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE0(munlockall)
|
|
{
|
|
int ret;
|
|
|
|
if (down_write_killable(¤t->mm->mmap_sem))
|
|
return -EINTR;
|
|
ret = apply_mlockall_flags(0);
|
|
up_write(¤t->mm->mmap_sem);
|
|
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 user_struct *user)
|
|
{
|
|
unsigned long lock_limit, locked;
|
|
int allowed = 0;
|
|
|
|
locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
if (lock_limit == RLIM_INFINITY)
|
|
allowed = 1;
|
|
lock_limit >>= PAGE_SHIFT;
|
|
spin_lock(&shmlock_user_lock);
|
|
if (!allowed &&
|
|
locked + user->locked_shm > lock_limit && !capable(CAP_IPC_LOCK))
|
|
goto out;
|
|
get_uid(user);
|
|
user->locked_shm += locked;
|
|
allowed = 1;
|
|
out:
|
|
spin_unlock(&shmlock_user_lock);
|
|
return allowed;
|
|
}
|
|
|
|
void user_shm_unlock(size_t size, struct user_struct *user)
|
|
{
|
|
spin_lock(&shmlock_user_lock);
|
|
user->locked_shm -= (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
spin_unlock(&shmlock_user_lock);
|
|
free_uid(user);
|
|
}
|