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![Hugh Dickins](/assets/img/avatar_default.png)
Since commitdc68badced
("mm: mlock: update mlock_pte_range to handle large folio") I've just occasionally seen VM_WARN_ON_FOLIO(folio_test_ksm) warnings from folio_within_range(), in a splurge after testing with KSM hyperactive. folio_referenced_one()'s use of folio_within_vma() is safe because it checks folio_test_large() first; but allow_mlock_munlock() needs to do the same to avoid those warnings (or check !folio_test_ksm() itself? Or move either check into folio_within_range()? Hard to tell without more examples of its use). Link: https://lkml.kernel.org/r/23852f6a-5bfa-1ffd-30db-30c5560ad426@google.com Fixes:dc68badced
("mm: mlock: update mlock_pte_range to handle large folio") Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Stefan Roesch <shr@devkernel.io> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
834 lines
21 KiB
C
834 lines
21 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/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_fbatch {
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local_lock_t lock;
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struct folio_batch fbatch;
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};
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static DEFINE_PER_CPU(struct mlock_fbatch, mlock_fbatch) = {
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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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* Mlocked folios are marked with the PG_mlocked 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 folio [folio_test_mlocked(folio)] is unevictable. As such, it
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* will be ostensibly placed on the LRU "unevictable" list (actually no such
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* list exists), rather than the [in]active lists. PG_unevictable is set to
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* indicate the unevictable state.
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*/
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static struct lruvec *__mlock_folio(struct folio *folio, 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 (!folio_test_clear_lru(folio))
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return lruvec;
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lruvec = folio_lruvec_relock_irq(folio, lruvec);
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if (unlikely(folio_evictable(folio))) {
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/*
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* This is a little surprising, but quite possible: PG_mlocked
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* must have got cleared already by another CPU. Could this
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* folio be unevictable? I'm not sure, but move it now if so.
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*/
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if (folio_test_unevictable(folio)) {
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lruvec_del_folio(lruvec, folio);
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folio_clear_unevictable(folio);
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lruvec_add_folio(lruvec, folio);
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__count_vm_events(UNEVICTABLE_PGRESCUED,
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folio_nr_pages(folio));
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}
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goto out;
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}
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if (folio_test_unevictable(folio)) {
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if (folio_test_mlocked(folio))
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folio->mlock_count++;
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goto out;
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}
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lruvec_del_folio(lruvec, folio);
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folio_clear_active(folio);
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folio_set_unevictable(folio);
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folio->mlock_count = !!folio_test_mlocked(folio);
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lruvec_add_folio(lruvec, folio);
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__count_vm_events(UNEVICTABLE_PGCULLED, folio_nr_pages(folio));
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out:
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folio_set_lru(folio);
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return lruvec;
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}
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static struct lruvec *__mlock_new_folio(struct folio *folio, struct lruvec *lruvec)
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{
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VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
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lruvec = folio_lruvec_relock_irq(folio, lruvec);
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/* As above, this is a little surprising, but possible */
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if (unlikely(folio_evictable(folio)))
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goto out;
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folio_set_unevictable(folio);
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folio->mlock_count = !!folio_test_mlocked(folio);
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__count_vm_events(UNEVICTABLE_PGCULLED, folio_nr_pages(folio));
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out:
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lruvec_add_folio(lruvec, folio);
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folio_set_lru(folio);
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return lruvec;
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}
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static struct lruvec *__munlock_folio(struct folio *folio, struct lruvec *lruvec)
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{
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int nr_pages = folio_nr_pages(folio);
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bool isolated = false;
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if (!folio_test_clear_lru(folio))
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goto munlock;
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isolated = true;
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lruvec = folio_lruvec_relock_irq(folio, lruvec);
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if (folio_test_unevictable(folio)) {
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/* Then mlock_count is maintained, but might undercount */
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if (folio->mlock_count)
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folio->mlock_count--;
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if (folio->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 (folio_test_clear_mlocked(folio)) {
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__zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
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if (isolated || !folio_test_unevictable(folio))
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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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/* folio_evictable() has to be checked *after* clearing Mlocked */
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if (isolated && folio_test_unevictable(folio) && folio_evictable(folio)) {
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lruvec_del_folio(lruvec, folio);
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folio_clear_unevictable(folio);
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lruvec_add_folio(lruvec, folio);
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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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folio_set_lru(folio);
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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 folio pointer on the mlock_fbatch.
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*/
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#define LRU_FOLIO 0x1
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#define NEW_FOLIO 0x2
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static inline struct folio *mlock_lru(struct folio *folio)
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{
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return (struct folio *)((unsigned long)folio + LRU_FOLIO);
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}
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static inline struct folio *mlock_new(struct folio *folio)
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{
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return (struct folio *)((unsigned long)folio + NEW_FOLIO);
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}
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/*
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* mlock_folio_batch() is derived from folio_batch_move_lru(): perhaps that can
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* make use of such folio pointer flags in future, but for now just keep it for
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* mlock. We could use three separate folio batches instead, but one feels
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* better (munlocking a full folio batch does not need to drain mlocking folio
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* batches first).
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*/
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static void mlock_folio_batch(struct folio_batch *fbatch)
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{
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struct lruvec *lruvec = NULL;
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unsigned long mlock;
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struct folio *folio;
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int i;
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for (i = 0; i < folio_batch_count(fbatch); i++) {
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folio = fbatch->folios[i];
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mlock = (unsigned long)folio & (LRU_FOLIO | NEW_FOLIO);
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folio = (struct folio *)((unsigned long)folio - mlock);
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fbatch->folios[i] = folio;
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if (mlock & LRU_FOLIO)
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lruvec = __mlock_folio(folio, lruvec);
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else if (mlock & NEW_FOLIO)
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lruvec = __mlock_new_folio(folio, lruvec);
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else
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lruvec = __munlock_folio(folio, lruvec);
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}
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if (lruvec)
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unlock_page_lruvec_irq(lruvec);
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folios_put(fbatch->folios, folio_batch_count(fbatch));
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folio_batch_reinit(fbatch);
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}
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void mlock_drain_local(void)
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{
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struct folio_batch *fbatch;
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local_lock(&mlock_fbatch.lock);
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fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
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if (folio_batch_count(fbatch))
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mlock_folio_batch(fbatch);
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local_unlock(&mlock_fbatch.lock);
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}
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void mlock_drain_remote(int cpu)
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{
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struct folio_batch *fbatch;
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WARN_ON_ONCE(cpu_online(cpu));
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fbatch = &per_cpu(mlock_fbatch.fbatch, cpu);
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if (folio_batch_count(fbatch))
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mlock_folio_batch(fbatch);
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}
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bool need_mlock_drain(int cpu)
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{
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return folio_batch_count(&per_cpu(mlock_fbatch.fbatch, 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 folio_batch *fbatch;
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local_lock(&mlock_fbatch.lock);
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fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
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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 (!folio_batch_add(fbatch, mlock_lru(folio)) ||
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folio_test_large(folio) || lru_cache_disabled())
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mlock_folio_batch(fbatch);
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local_unlock(&mlock_fbatch.lock);
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}
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/**
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* mlock_new_folio - mlock a newly allocated folio not yet on LRU
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* @folio: folio to be mlocked, either normal or a THP head.
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*/
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void mlock_new_folio(struct folio *folio)
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{
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struct folio_batch *fbatch;
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int nr_pages = folio_nr_pages(folio);
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local_lock(&mlock_fbatch.lock);
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fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
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folio_set_mlocked(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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folio_get(folio);
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if (!folio_batch_add(fbatch, mlock_new(folio)) ||
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folio_test_large(folio) || lru_cache_disabled())
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mlock_folio_batch(fbatch);
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local_unlock(&mlock_fbatch.lock);
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}
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/**
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* munlock_folio - munlock a folio
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* @folio: folio to be munlocked, either normal or a THP head.
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*/
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void munlock_folio(struct folio *folio)
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{
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struct folio_batch *fbatch;
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local_lock(&mlock_fbatch.lock);
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fbatch = this_cpu_ptr(&mlock_fbatch.fbatch);
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/*
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* folio_test_clear_mlocked(folio) must be left to __munlock_folio(),
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* which will check whether the folio is multiply mlocked.
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*/
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folio_get(folio);
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if (!folio_batch_add(fbatch, folio) ||
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folio_test_large(folio) || lru_cache_disabled())
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mlock_folio_batch(fbatch);
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local_unlock(&mlock_fbatch.lock);
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}
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static inline unsigned int folio_mlock_step(struct folio *folio,
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pte_t *pte, unsigned long addr, unsigned long end)
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{
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unsigned int count, i, nr = folio_nr_pages(folio);
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unsigned long pfn = folio_pfn(folio);
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pte_t ptent = ptep_get(pte);
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if (!folio_test_large(folio))
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return 1;
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count = pfn + nr - pte_pfn(ptent);
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count = min_t(unsigned int, count, (end - addr) >> PAGE_SHIFT);
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for (i = 0; i < count; i++, pte++) {
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pte_t entry = ptep_get(pte);
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if (!pte_present(entry))
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break;
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if (pte_pfn(entry) - pfn >= nr)
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break;
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}
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return i;
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}
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static inline bool allow_mlock_munlock(struct folio *folio,
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struct vm_area_struct *vma, unsigned long start,
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unsigned long end, unsigned int step)
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{
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/*
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* For unlock, allow munlock large folio which is partially
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* mapped to VMA. As it's possible that large folio is
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* mlocked and VMA is split later.
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*
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* During memory pressure, such kind of large folio can
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* be split. And the pages are not in VM_LOCKed VMA
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* can be reclaimed.
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*/
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if (!(vma->vm_flags & VM_LOCKED))
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return true;
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/* folio_within_range() cannot take KSM, but any small folio is OK */
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if (!folio_test_large(folio))
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return true;
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/* folio not in range [start, end), skip mlock */
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if (!folio_within_range(folio, vma, start, end))
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return false;
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/* folio is not fully mapped, skip mlock */
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if (step != folio_nr_pages(folio))
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return false;
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return true;
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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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pte_t ptent;
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struct folio *folio;
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unsigned int step = 1;
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unsigned long start = addr;
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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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folio = page_folio(pmd_page(*pmd));
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if (vma->vm_flags & VM_LOCKED)
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mlock_folio(folio);
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else
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munlock_folio(folio);
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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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if (!start_pte) {
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walk->action = ACTION_AGAIN;
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return 0;
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}
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for (pte = start_pte; addr != end; pte++, addr += PAGE_SIZE) {
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ptent = ptep_get(pte);
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if (!pte_present(ptent))
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continue;
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folio = vm_normal_folio(vma, addr, ptent);
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if (!folio || folio_is_zone_device(folio))
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continue;
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step = folio_mlock_step(folio, pte, addr, end);
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if (!allow_mlock_munlock(folio, vma, start, end, step))
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goto next_entry;
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if (vma->vm_flags & VM_LOCKED)
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mlock_folio(folio);
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else
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munlock_folio(folio);
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next_entry:
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pte += step - 1;
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addr += (step - 1) << PAGE_SHIFT;
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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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.walk_lock = PGWALK_WRLOCK_VERIFY,
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};
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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_folio() 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_folio() 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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vma_start_write(vma);
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vm_flags_reset_once(vma, 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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|
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if (newflags & VM_IO) {
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newflags &= ~VM_IO;
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vm_flags_reset_once(vma, newflags);
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}
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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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|
*
|
|
* 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 vma_iterator *vmi, 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;
|
|
int nr_pages;
|
|
int ret = 0;
|
|
vm_flags_t oldflags = vma->vm_flags;
|
|
|
|
if (newflags == oldflags || (oldflags & VM_SPECIAL) ||
|
|
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
|
|
vma_is_dax(vma) || vma_is_secretmem(vma))
|
|
/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
|
|
goto out;
|
|
|
|
vma = vma_modify_flags(vmi, *prev, vma, start, end, newflags);
|
|
if (IS_ERR(vma)) {
|
|
ret = PTR_ERR(vma);
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Keep track of amount of locked VM.
|
|
*/
|
|
nr_pages = (end - start) >> PAGE_SHIFT;
|
|
if (!(newflags & VM_LOCKED))
|
|
nr_pages = -nr_pages;
|
|
else if (oldflags & VM_LOCKED)
|
|
nr_pages = 0;
|
|
mm->locked_vm += nr_pages;
|
|
|
|
/*
|
|
* vm_flags is protected by the mmap_lock 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 ((newflags & VM_LOCKED) && (oldflags & VM_LOCKED)) {
|
|
/* No work to do, and mlocking twice would be wrong */
|
|
vma_start_write(vma);
|
|
vm_flags_reset(vma, newflags);
|
|
} else {
|
|
mlock_vma_pages_range(vma, start, end, newflags);
|
|
}
|
|
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;
|
|
VMA_ITERATOR(vmi, current->mm, start);
|
|
|
|
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 = vma_iter_load(&vmi);
|
|
if (!vma)
|
|
return -ENOMEM;
|
|
|
|
prev = vma_prev(&vmi);
|
|
if (start > vma->vm_start)
|
|
prev = vma;
|
|
|
|
nstart = start;
|
|
tmp = vma->vm_start;
|
|
for_each_vma_range(vmi, vma, end) {
|
|
int error;
|
|
vm_flags_t newflags;
|
|
|
|
if (vma->vm_start != tmp)
|
|
return -ENOMEM;
|
|
|
|
newflags = vma->vm_flags & ~VM_LOCKED_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(&vmi, vma, &prev, nstart, tmp, newflags);
|
|
if (error)
|
|
return error;
|
|
tmp = vma_iter_end(&vmi);
|
|
nstart = tmp;
|
|
}
|
|
|
|
if (tmp < end)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
unsigned long end;
|
|
VMA_ITERATOR(vmi, mm, start);
|
|
|
|
/* Don't overflow past ULONG_MAX */
|
|
if (unlikely(ULONG_MAX - len < start))
|
|
end = ULONG_MAX;
|
|
else
|
|
end = start + len;
|
|
|
|
for_each_vma_range(vmi, vma, end) {
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
if (start > vma->vm_start)
|
|
count -= (start - vma->vm_start);
|
|
if (end < vma->vm_end) {
|
|
count += end - vma->vm_start;
|
|
break;
|
|
}
|
|
count += vma->vm_end - vma->vm_start;
|
|
}
|
|
}
|
|
|
|
return count >> PAGE_SHIFT;
|
|
}
|
|
|
|
/*
|
|
* convert get_user_pages() return value to posix mlock() error
|
|
*/
|
|
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)
|
|
{
|
|
VMA_ITERATOR(vmi, current->mm, 0);
|
|
struct vm_area_struct *vma, *prev = NULL;
|
|
vm_flags_t to_add = 0;
|
|
|
|
current->mm->def_flags &= ~VM_LOCKED_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_each_vma(vmi, vma) {
|
|
vm_flags_t newflags;
|
|
|
|
newflags = vma->vm_flags & ~VM_LOCKED_MASK;
|
|
newflags |= to_add;
|
|
|
|
/* Ignore errors */
|
|
mlock_fixup(&vmi, 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);
|
|
}
|