summaryrefslogtreecommitdiffstats
path: root/mm/mlock.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/mlock.c')
-rw-r--r--mm/mlock.c868
1 files changed, 868 insertions, 0 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
new file mode 100644
index 000000000..0ab8250af
--- /dev/null
+++ b/mm/mlock.c
@@ -0,0 +1,868 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/mm/mlock.c
+ *
+ * (C) Copyright 1995 Linus Torvalds
+ * (C) Copyright 2002 Christoph Hellwig
+ */
+
+#include <linux/capability.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/sched/user.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/mempolicy.h>
+#include <linux/syscalls.h>
+#include <linux/sched.h>
+#include <linux/export.h>
+#include <linux/rmap.h>
+#include <linux/mmzone.h>
+#include <linux/hugetlb.h>
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
+
+#include "internal.h"
+
+bool can_do_mlock(void)
+{
+ if (rlimit(RLIMIT_MEMLOCK) != 0)
+ return true;
+ if (capable(CAP_IPC_LOCK))
+ return true;
+ return false;
+}
+EXPORT_SYMBOL(can_do_mlock);
+
+/*
+ * Mlocked pages are marked with PageMlocked() flag for efficient testing
+ * in vmscan and, possibly, the fault path; and to support semi-accurate
+ * statistics.
+ *
+ * An mlocked page [PageMlocked(page)] is unevictable. As such, it will
+ * be placed on the LRU "unevictable" list, rather than the [in]active lists.
+ * The unevictable list is an LRU sibling list to the [in]active lists.
+ * PageUnevictable is set to indicate the unevictable state.
+ *
+ * When lazy mlocking via vmscan, it is important to ensure that the
+ * vma's VM_LOCKED status is not concurrently being modified, otherwise we
+ * may have mlocked a page that is being munlocked. So lazy mlock must take
+ * the mmap_sem for read, and verify that the vma really is locked
+ * (see mm/rmap.c).
+ */
+
+/*
+ * LRU accounting for clear_page_mlock()
+ */
+void clear_page_mlock(struct page *page)
+{
+ if (!TestClearPageMlocked(page))
+ return;
+
+ mod_zone_page_state(page_zone(page), NR_MLOCK,
+ -hpage_nr_pages(page));
+ count_vm_event(UNEVICTABLE_PGCLEARED);
+ /*
+ * The previous TestClearPageMlocked() corresponds to the smp_mb()
+ * in __pagevec_lru_add_fn().
+ *
+ * See __pagevec_lru_add_fn for more explanation.
+ */
+ if (!isolate_lru_page(page)) {
+ putback_lru_page(page);
+ } else {
+ /*
+ * We lost the race. the page already moved to evictable list.
+ */
+ if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+ }
+}
+
+/*
+ * Mark page as mlocked if not already.
+ * If page on LRU, isolate and putback to move to unevictable list.
+ */
+void mlock_vma_page(struct page *page)
+{
+ /* Serialize with page migration */
+ BUG_ON(!PageLocked(page));
+
+ VM_BUG_ON_PAGE(PageTail(page), page);
+ VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
+
+ if (!TestSetPageMlocked(page)) {
+ mod_zone_page_state(page_zone(page), NR_MLOCK,
+ hpage_nr_pages(page));
+ count_vm_event(UNEVICTABLE_PGMLOCKED);
+ if (!isolate_lru_page(page))
+ putback_lru_page(page);
+ }
+}
+
+/*
+ * Isolate a page from LRU with optional get_page() pin.
+ * Assumes lru_lock already held and page already pinned.
+ */
+static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
+{
+ if (PageLRU(page)) {
+ struct lruvec *lruvec;
+
+ lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
+ if (getpage)
+ get_page(page);
+ ClearPageLRU(page);
+ del_page_from_lru_list(page, lruvec, page_lru(page));
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Finish munlock after successful page isolation
+ *
+ * Page must be locked. This is a wrapper for try_to_munlock()
+ * and putback_lru_page() with munlock accounting.
+ */
+static void __munlock_isolated_page(struct page *page)
+{
+ /*
+ * Optimization: if the page was mapped just once, that's our mapping
+ * and we don't need to check all the other vmas.
+ */
+ if (page_mapcount(page) > 1)
+ try_to_munlock(page);
+
+ /* Did try_to_unlock() succeed or punt? */
+ if (!PageMlocked(page))
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
+ putback_lru_page(page);
+}
+
+/*
+ * Accounting for page isolation fail during munlock
+ *
+ * Performs accounting when page isolation fails in munlock. There is nothing
+ * else to do because it means some other task has already removed the page
+ * from the LRU. putback_lru_page() will take care of removing the page from
+ * the unevictable list, if necessary. vmscan [page_referenced()] will move
+ * the page back to the unevictable list if some other vma has it mlocked.
+ */
+static void __munlock_isolation_failed(struct page *page)
+{
+ if (PageUnevictable(page))
+ __count_vm_event(UNEVICTABLE_PGSTRANDED);
+ else
+ __count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+}
+
+/**
+ * munlock_vma_page - munlock a vma page
+ * @page: page to be unlocked, either a normal page or THP page head
+ *
+ * returns the size of the page as a page mask (0 for normal page,
+ * HPAGE_PMD_NR - 1 for THP head page)
+ *
+ * called from munlock()/munmap() path with page supposedly on the LRU.
+ * When we munlock a page, because the vma where we found the page is being
+ * munlock()ed or munmap()ed, we want to check whether other vmas hold the
+ * page locked so that we can leave it on the unevictable lru list and not
+ * bother vmscan with it. However, to walk the page's rmap list in
+ * try_to_munlock() we must isolate the page from the LRU. If some other
+ * task has removed the page from the LRU, we won't be able to do that.
+ * So we clear the PageMlocked as we might not get another chance. If we
+ * can't isolate the page, we leave it for putback_lru_page() and vmscan
+ * [page_referenced()/try_to_unmap()] to deal with.
+ */
+unsigned int munlock_vma_page(struct page *page)
+{
+ int nr_pages;
+ struct zone *zone = page_zone(page);
+
+ /* For try_to_munlock() and to serialize with page migration */
+ BUG_ON(!PageLocked(page));
+
+ VM_BUG_ON_PAGE(PageTail(page), page);
+
+ /*
+ * Serialize with any parallel __split_huge_page_refcount() which
+ * might otherwise copy PageMlocked to part of the tail pages before
+ * we clear it in the head page. It also stabilizes hpage_nr_pages().
+ */
+ spin_lock_irq(zone_lru_lock(zone));
+
+ if (!TestClearPageMlocked(page)) {
+ /* Potentially, PTE-mapped THP: do not skip the rest PTEs */
+ nr_pages = 1;
+ goto unlock_out;
+ }
+
+ nr_pages = hpage_nr_pages(page);
+ __mod_zone_page_state(zone, NR_MLOCK, -nr_pages);
+
+ if (__munlock_isolate_lru_page(page, true)) {
+ spin_unlock_irq(zone_lru_lock(zone));
+ __munlock_isolated_page(page);
+ goto out;
+ }
+ __munlock_isolation_failed(page);
+
+unlock_out:
+ spin_unlock_irq(zone_lru_lock(zone));
+
+out:
+ return nr_pages - 1;
+}
+
+/*
+ * 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;
+}
+
+/*
+ * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
+ *
+ * The fast path is available only for evictable pages with single mapping.
+ * Then we can bypass the per-cpu pvec and get better performance.
+ * when mapcount > 1 we need try_to_munlock() which can fail.
+ * when !page_evictable(), we need the full redo logic of putback_lru_page to
+ * avoid leaving evictable page in unevictable list.
+ *
+ * In case of success, @page is added to @pvec and @pgrescued is incremented
+ * in case that the page was previously unevictable. @page is also unlocked.
+ */
+static bool __putback_lru_fast_prepare(struct page *page, struct pagevec *pvec,
+ int *pgrescued)
+{
+ VM_BUG_ON_PAGE(PageLRU(page), page);
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+ if (page_mapcount(page) <= 1 && page_evictable(page)) {
+ pagevec_add(pvec, page);
+ if (TestClearPageUnevictable(page))
+ (*pgrescued)++;
+ unlock_page(page);
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Putback multiple evictable pages to the LRU
+ *
+ * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
+ * the pages might have meanwhile become unevictable but that is OK.
+ */
+static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
+{
+ count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
+ /*
+ *__pagevec_lru_add() calls release_pages() so we don't call
+ * put_page() explicitly
+ */
+ __pagevec_lru_add(pvec);
+ count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
+}
+
+/*
+ * Munlock a batch of pages from the same zone
+ *
+ * The work is split to two main phases. First phase clears the Mlocked flag
+ * and attempts to isolate the pages, all under a single zone lru lock.
+ * The second phase finishes the munlock only for pages where isolation
+ * succeeded.
+ *
+ * Note that the pagevec may be modified during the process.
+ */
+static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
+{
+ int i;
+ int nr = pagevec_count(pvec);
+ int delta_munlocked = -nr;
+ struct pagevec pvec_putback;
+ int pgrescued = 0;
+
+ pagevec_init(&pvec_putback);
+
+ /* Phase 1: page isolation */
+ spin_lock_irq(zone_lru_lock(zone));
+ for (i = 0; i < nr; i++) {
+ struct page *page = pvec->pages[i];
+
+ if (TestClearPageMlocked(page)) {
+ /*
+ * We already have pin from follow_page_mask()
+ * so we can spare the get_page() here.
+ */
+ if (__munlock_isolate_lru_page(page, false))
+ continue;
+ else
+ __munlock_isolation_failed(page);
+ } else {
+ delta_munlocked++;
+ }
+
+ /*
+ * We won't be munlocking this page in the next phase
+ * but we still need to release the follow_page_mask()
+ * pin. We cannot do it under lru_lock however. If it's
+ * the last pin, __page_cache_release() would deadlock.
+ */
+ pagevec_add(&pvec_putback, pvec->pages[i]);
+ pvec->pages[i] = NULL;
+ }
+ __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
+ spin_unlock_irq(zone_lru_lock(zone));
+
+ /* Now we can release pins of pages that we are not munlocking */
+ pagevec_release(&pvec_putback);
+
+ /* Phase 2: page munlock */
+ for (i = 0; i < nr; i++) {
+ struct page *page = pvec->pages[i];
+
+ if (page) {
+ lock_page(page);
+ if (!__putback_lru_fast_prepare(page, &pvec_putback,
+ &pgrescued)) {
+ /*
+ * Slow path. We don't want to lose the last
+ * pin before unlock_page()
+ */
+ get_page(page); /* for putback_lru_page() */
+ __munlock_isolated_page(page);
+ unlock_page(page);
+ put_page(page); /* from follow_page_mask() */
+ }
+ }
+ }
+
+ /*
+ * Phase 3: page putback for pages that qualified for the fast path
+ * This will also call put_page() to return pin from follow_page_mask()
+ */
+ if (pagevec_count(&pvec_putback))
+ __putback_lru_fast(&pvec_putback, pgrescued);
+}
+
+/*
+ * Fill up pagevec for __munlock_pagevec using pte walk
+ *
+ * The function expects that the struct page corresponding to @start address is
+ * a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
+ *
+ * The rest of @pvec is filled by subsequent pages within the same pmd and same
+ * zone, as long as the pte's are present and vm_normal_page() succeeds. These
+ * pages also get pinned.
+ *
+ * Returns the address of the next page that should be scanned. This equals
+ * @start + PAGE_SIZE when no page could be added by the pte walk.
+ */
+static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
+ struct vm_area_struct *vma, struct zone *zone,
+ unsigned long start, unsigned long end)
+{
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ /*
+ * Initialize pte walk starting at the already pinned page where we
+ * are sure that there is a pte, as it was pinned under the same
+ * mmap_sem write op.
+ */
+ pte = get_locked_pte(vma->vm_mm, start, &ptl);
+ /* Make sure we do not cross the page table boundary */
+ end = pgd_addr_end(start, end);
+ end = p4d_addr_end(start, end);
+ end = pud_addr_end(start, end);
+ end = pmd_addr_end(start, end);
+
+ /* The page next to the pinned page is the first we will try to get */
+ start += PAGE_SIZE;
+ while (start < end) {
+ struct page *page = NULL;
+ pte++;
+ if (pte_present(*pte))
+ page = vm_normal_page(vma, start, *pte);
+ /*
+ * Break if page could not be obtained or the page's node+zone does not
+ * match
+ */
+ if (!page || page_zone(page) != zone)
+ break;
+
+ /*
+ * Do not use pagevec for PTE-mapped THP,
+ * munlock_vma_pages_range() will handle them.
+ */
+ if (PageTransCompound(page))
+ break;
+
+ get_page(page);
+ /*
+ * Increase the address that will be returned *before* the
+ * eventual break due to pvec becoming full by adding the page
+ */
+ start += PAGE_SIZE;
+ if (pagevec_add(pvec, page) == 0)
+ break;
+ }
+ pte_unmap_unlock(pte, ptl);
+ return start;
+}
+
+/*
+ * munlock_vma_pages_range() - munlock all pages in the vma range.'
+ * @vma - vma containing range to be munlock()ed.
+ * @start - start address in @vma of the range
+ * @end - end of range in @vma.
+ *
+ * For mremap(), munmap() and exit().
+ *
+ * Called with @vma VM_LOCKED.
+ *
+ * Returns with VM_LOCKED cleared. Callers must be prepared to
+ * deal with this.
+ *
+ * We don't save and restore VM_LOCKED here because pages are
+ * still on lru. In unmap path, pages might be scanned by reclaim
+ * and re-mlocked by try_to_{munlock|unmap} before we unmap and
+ * free them. This will result in freeing mlocked pages.
+ */
+void munlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end)
+{
+ vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+
+ while (start < end) {
+ struct page *page;
+ unsigned int page_mask = 0;
+ unsigned long page_increm;
+ struct pagevec pvec;
+ struct zone *zone;
+
+ pagevec_init(&pvec);
+ /*
+ * Although FOLL_DUMP is intended for get_dump_page(),
+ * it just so happens that its special treatment of the
+ * ZERO_PAGE (returning an error instead of doing get_page)
+ * suits munlock very well (and if somehow an abnormal page
+ * has sneaked into the range, we won't oops here: great).
+ */
+ page = follow_page(vma, start, FOLL_GET | FOLL_DUMP);
+
+ if (page && !IS_ERR(page)) {
+ if (PageTransTail(page)) {
+ VM_BUG_ON_PAGE(PageMlocked(page), page);
+ put_page(page); /* follow_page_mask() */
+ } else if (PageTransHuge(page)) {
+ lock_page(page);
+ /*
+ * Any THP page found by follow_page_mask() may
+ * have gotten split before reaching
+ * munlock_vma_page(), so we need to compute
+ * the page_mask here instead.
+ */
+ page_mask = munlock_vma_page(page);
+ unlock_page(page);
+ put_page(page); /* follow_page_mask() */
+ } else {
+ /*
+ * Non-huge pages are handled in batches via
+ * pagevec. The pin from follow_page_mask()
+ * prevents them from collapsing by THP.
+ */
+ pagevec_add(&pvec, page);
+ zone = page_zone(page);
+
+ /*
+ * Try to fill the rest of pagevec using fast
+ * pte walk. This will also update start to
+ * the next page to process. Then munlock the
+ * pagevec.
+ */
+ 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;
+
+ 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(&current->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(&current->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;
+
+ len = PAGE_ALIGN(len + (offset_in_page(start)));
+ start &= PAGE_MASK;
+
+ if (down_write_killable(&current->mm->mmap_sem))
+ return -EINTR;
+ ret = apply_vma_lock_flags(start, len, 0);
+ up_write(&current->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)))
+ return -EINVAL;
+
+ if (!can_do_mlock())
+ return -EPERM;
+
+ lock_limit = rlimit(RLIMIT_MEMLOCK);
+ lock_limit >>= PAGE_SHIFT;
+
+ if (down_write_killable(&current->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(&current->mm->mmap_sem);
+ if (!ret && (flags & MCL_CURRENT))
+ mm_populate(0, TASK_SIZE);
+
+ return ret;
+}
+
+SYSCALL_DEFINE0(munlockall)
+{
+ int ret;
+
+ if (down_write_killable(&current->mm->mmap_sem))
+ return -EINTR;
+ ret = apply_mlockall_flags(0);
+ up_write(&current->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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-01 01:42:10 +0000