| // 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 <linux/secretmem.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_lock 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) |
| { |
| int nr_pages; |
| |
| if (!TestClearPageMlocked(page)) |
| return; |
| |
| nr_pages = thp_nr_pages(page); |
| mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); |
| count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages); |
| /* |
| * 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_events(UNEVICTABLE_PGSTRANDED, nr_pages); |
| } |
| } |
| |
| /* |
| * 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)) { |
| int nr_pages = thp_nr_pages(page); |
| |
| mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages); |
| count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); |
| if (!isolate_lru_page(page)) |
| putback_lru_page(page); |
| } |
| } |
| |
| /* |
| * Finish munlock after successful page isolation |
| * |
| * Page must be locked. This is a wrapper for page_mlock() |
| * 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) |
| page_mlock(page); |
| |
| /* Did try_to_unlock() succeed or punt? */ |
| if (!PageMlocked(page)) |
| count_vm_events(UNEVICTABLE_PGMUNLOCKED, thp_nr_pages(page)); |
| |
| 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) |
| { |
| int nr_pages = thp_nr_pages(page); |
| |
| if (PageUnevictable(page)) |
| __count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages); |
| else |
| __count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages); |
| } |
| |
| /** |
| * 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 |
| * page_mlock() 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; |
| |
| /* For page_mlock() and to serialize with page migration */ |
| BUG_ON(!PageLocked(page)); |
| VM_BUG_ON_PAGE(PageTail(page), page); |
| |
| if (!TestClearPageMlocked(page)) { |
| /* Potentially, PTE-mapped THP: do not skip the rest PTEs */ |
| return 0; |
| } |
| |
| nr_pages = thp_nr_pages(page); |
| mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); |
| |
| if (!isolate_lru_page(page)) |
| __munlock_isolated_page(page); |
| else |
| __munlock_isolation_failed(page); |
| |
| 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 page_mlock() 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; |
| struct lruvec *lruvec = NULL; |
| int pgrescued = 0; |
| |
| pagevec_init(&pvec_putback); |
| |
| /* Phase 1: page isolation */ |
| for (i = 0; i < nr; i++) { |
| struct page *page = pvec->pages[i]; |
| struct folio *folio = page_folio(page); |
| |
| if (TestClearPageMlocked(page)) { |
| /* |
| * We already have pin from follow_page_mask() |
| * so we can spare the get_page() here. |
| */ |
| if (TestClearPageLRU(page)) { |
| lruvec = folio_lruvec_relock_irq(folio, lruvec); |
| del_page_from_lru_list(page, lruvec); |
| 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; |
| } |
| if (lruvec) { |
| __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); |
| unlock_page_lruvec_irq(lruvec); |
| } else if (delta_munlocked) { |
| mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); |
| } |
| |
| /* 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_lock 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 page_mlock/try_to_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) || vma_is_secretmem(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, anon_vma_name(vma)); |
| 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_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 (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) |
| return 0; |
| |
| 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 (mmap_write_lock_killable(current->mm)) |
| return -EINTR; |
| |
| locked += current->mm->locked_vm; |
| if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) { |
| /* |
| * It is possible that the regions requested intersect with |
| * previously mlocked areas, that part area in "mm->locked_vm" |
| * should not be counted to new mlock increment count. So check |
| * and adjust locked count if necessary. |
| */ |
| locked -= count_mm_mlocked_page_nr(current->mm, |
| start, len); |
| } |
| |
| /* check against resource limits */ |
| if ((locked <= lock_limit) || capable(CAP_IPC_LOCK)) |
| error = apply_vma_lock_flags(start, len, flags); |
| |
| mmap_write_unlock(current->mm); |
| if (error) |
| return error; |
| |
| error = __mm_populate(start, len, 0); |
| if (error) |
| return __mlock_posix_error_return(error); |
| return 0; |
| } |
| |
| SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len) |
| { |
| return do_mlock(start, len, VM_LOCKED); |
| } |
| |
| SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags) |
| { |
| vm_flags_t vm_flags = VM_LOCKED; |
| |
| if (flags & ~MLOCK_ONFAULT) |
| return -EINVAL; |
| |
| if (flags & MLOCK_ONFAULT) |
| vm_flags |= VM_LOCKONFAULT; |
| |
| return do_mlock(start, len, vm_flags); |
| } |
| |
| SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) |
| { |
| int ret; |
| |
| start = untagged_addr(start); |
| |
| len = PAGE_ALIGN(len + (offset_in_page(start))); |
| start &= PAGE_MASK; |
| |
| if (mmap_write_lock_killable(current->mm)) |
| return -EINTR; |
| ret = apply_vma_lock_flags(start, len, 0); |
| mmap_write_unlock(current->mm); |
| |
| return ret; |
| } |
| |
| /* |
| * Take the MCL_* flags passed into mlockall (or 0 if called from munlockall) |
| * and translate into the appropriate modifications to mm->def_flags and/or the |
| * flags for all current VMAs. |
| * |
| * There are a couple of subtleties with this. If mlockall() is called multiple |
| * times with different flags, the values do not necessarily stack. If mlockall |
| * is called once including the MCL_FUTURE flag and then a second time without |
| * it, VM_LOCKED and VM_LOCKONFAULT will be cleared from mm->def_flags. |
| */ |
| static int apply_mlockall_flags(int flags) |
| { |
| struct vm_area_struct *vma, *prev = NULL; |
| vm_flags_t to_add = 0; |
| |
| current->mm->def_flags &= VM_LOCKED_CLEAR_MASK; |
| if (flags & MCL_FUTURE) { |
| current->mm->def_flags |= VM_LOCKED; |
| |
| if (flags & MCL_ONFAULT) |
| current->mm->def_flags |= VM_LOCKONFAULT; |
| |
| if (!(flags & MCL_CURRENT)) |
| goto out; |
| } |
| |
| if (flags & MCL_CURRENT) { |
| to_add |= VM_LOCKED; |
| if (flags & MCL_ONFAULT) |
| to_add |= VM_LOCKONFAULT; |
| } |
| |
| for (vma = current->mm->mmap; vma ; vma = prev->vm_next) { |
| vm_flags_t newflags; |
| |
| newflags = vma->vm_flags & VM_LOCKED_CLEAR_MASK; |
| newflags |= to_add; |
| |
| /* Ignore errors */ |
| mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); |
| cond_resched(); |
| } |
| out: |
| return 0; |
| } |
| |
| SYSCALL_DEFINE1(mlockall, int, flags) |
| { |
| unsigned long lock_limit; |
| int ret; |
| |
| if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ONFAULT)) || |
| flags == MCL_ONFAULT) |
| return -EINVAL; |
| |
| if (!can_do_mlock()) |
| return -EPERM; |
| |
| lock_limit = rlimit(RLIMIT_MEMLOCK); |
| lock_limit >>= PAGE_SHIFT; |
| |
| if (mmap_write_lock_killable(current->mm)) |
| return -EINTR; |
| |
| ret = -ENOMEM; |
| if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) || |
| capable(CAP_IPC_LOCK)) |
| ret = apply_mlockall_flags(flags); |
| mmap_write_unlock(current->mm); |
| if (!ret && (flags & MCL_CURRENT)) |
| mm_populate(0, TASK_SIZE); |
| |
| return ret; |
| } |
| |
| SYSCALL_DEFINE0(munlockall) |
| { |
| int ret; |
| |
| if (mmap_write_lock_killable(current->mm)) |
| return -EINTR; |
| ret = apply_mlockall_flags(0); |
| mmap_write_unlock(current->mm); |
| return ret; |
| } |
| |
| /* |
| * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB |
| * shm segments) get accounted against the user_struct instead. |
| */ |
| static DEFINE_SPINLOCK(shmlock_user_lock); |
| |
| int user_shm_lock(size_t size, struct ucounts *ucounts) |
| { |
| unsigned long lock_limit, locked; |
| long memlock; |
| int allowed = 0; |
| |
| locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| lock_limit = rlimit(RLIMIT_MEMLOCK); |
| if (lock_limit == RLIM_INFINITY) |
| allowed = 1; |
| lock_limit >>= PAGE_SHIFT; |
| spin_lock(&shmlock_user_lock); |
| memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked); |
| |
| if (!allowed && (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); |
| 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); |
| } |