return;
}
+ dec_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGCLEARED);
if (!isolate_lru_page(page)) {
putback_lru_page(page);
} else {
lru_add_drain_all();
if (!isolate_lru_page(page))
putback_lru_page(page);
+ else if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+
}
}
{
BUG_ON(!PageLocked(page));
- if (!TestSetPageMlocked(page) && !isolate_lru_page(page))
- putback_lru_page(page);
+ if (!TestSetPageMlocked(page)) {
+ inc_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGMLOCKED);
+ if (!isolate_lru_page(page))
+ putback_lru_page(page);
+ }
}
/*
{
BUG_ON(!PageLocked(page));
- if (TestClearPageMlocked(page) && !isolate_lru_page(page)) {
- try_to_munlock(page);
- putback_lru_page(page);
+ if (TestClearPageMlocked(page)) {
+ dec_zone_page_state(page, NR_MLOCK);
+ if (!isolate_lru_page(page)) {
+ int ret = try_to_munlock(page);
+ /*
+ * did try_to_unlock() succeed or punt?
+ */
+ if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN)
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
+ putback_lru_page(page);
+ } else {
+ /*
+ * We lost the race. let try_to_unmap() deal
+ * with it. At least we get the page state and
+ * mlock stats right. However, page is still on
+ * the noreclaim list. We'll fix that up when
+ * the page is eventually freed or we scan the
+ * noreclaim list.
+ */
+ if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+ else
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+ }
}
}
-/*
- * mlock a range of pages in the vma.
+/**
+ * __mlock_vma_pages_range() - mlock/munlock a range of pages in the vma.
+ * @vma: target vma
+ * @start: start address
+ * @end: end address
+ * @mlock: 0 indicate munlock, otherwise mlock.
*
- * This takes care of making the pages present too.
+ * If @mlock == 0, unlock an mlocked range;
+ * else mlock the range of pages. This takes care of making the pages present ,
+ * too.
*
- * vma->vm_mm->mmap_sem must be held for write.
+ * return 0 on success, negative error code on error.
+ *
+ * vma->vm_mm->mmap_sem must be held for at least read.
*/
-static int __mlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
+static long __mlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end,
+ int mlock)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long addr = start;
struct page *pages[16]; /* 16 gives a reasonable batch */
- int write = !!(vma->vm_flags & VM_WRITE);
int nr_pages = (end - start) / PAGE_SIZE;
int ret;
+ int gup_flags = 0;
- VM_BUG_ON(start & ~PAGE_MASK || end & ~PAGE_MASK);
- VM_BUG_ON(start < vma->vm_start || end > vma->vm_end);
- VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
+ VM_BUG_ON(start & ~PAGE_MASK);
+ VM_BUG_ON(end & ~PAGE_MASK);
+ VM_BUG_ON(start < vma->vm_start);
+ VM_BUG_ON(end > vma->vm_end);
+ VM_BUG_ON((!rwsem_is_locked(&mm->mmap_sem)) &&
+ (atomic_read(&mm->mm_users) != 0));
+
+ /*
+ * mlock: don't page populate if page has PROT_NONE permission.
+ * munlock: the pages always do munlock althrough
+ * its has PROT_NONE permission.
+ */
+ if (!mlock)
+ gup_flags |= GUP_FLAGS_IGNORE_VMA_PERMISSIONS;
+
+ if (vma->vm_flags & VM_WRITE)
+ gup_flags |= GUP_FLAGS_WRITE;
lru_add_drain_all(); /* push cached pages to LRU */
* disable migration of this page. However, page may
* still be truncated out from under us.
*/
- ret = get_user_pages(current, mm, addr,
+ ret = __get_user_pages(current, mm, addr,
min_t(int, nr_pages, ARRAY_SIZE(pages)),
- write, 0, pages, NULL);
+ gup_flags, pages, NULL);
/*
* This can happen for, e.g., VM_NONLINEAR regions before
* a page has been allocated and mapped at a given offset,
* by the elevated reference, we need only check for
* page truncation (file-cache only).
*/
- if (page->mapping)
- mlock_vma_page(page);
+ if (page->mapping) {
+ if (mlock)
+ mlock_vma_page(page);
+ else
+ munlock_vma_page(page);
+ }
unlock_page(page);
put_page(page); /* ref from get_user_pages() */
addr += PAGE_SIZE; /* for next get_user_pages() */
nr_pages--;
}
+ ret = 0;
}
lru_add_drain_all(); /* to update stats */
- return 0; /* count entire vma as locked_vm */
+ return ret; /* count entire vma as locked_vm */
}
/*
- * private structure for munlock page table walk
- */
-struct munlock_page_walk {
- struct vm_area_struct *vma;
- pmd_t *pmd; /* for migration_entry_wait() */
-};
-
-/*
- * munlock normal pages for present ptes
+ * convert get_user_pages() return value to posix mlock() error
*/
-static int __munlock_pte_handler(pte_t *ptep, unsigned long addr,
- unsigned long end, struct mm_walk *walk)
+static int __mlock_posix_error_return(long retval)
{
- struct munlock_page_walk *mpw = walk->private;
- swp_entry_t entry;
- struct page *page;
- pte_t pte;
-
-retry:
- pte = *ptep;
- /*
- * If it's a swap pte, we might be racing with page migration.
- */
- if (unlikely(!pte_present(pte))) {
- if (!is_swap_pte(pte))
- goto out;
- entry = pte_to_swp_entry(pte);
- if (is_migration_entry(entry)) {
- migration_entry_wait(mpw->vma->vm_mm, mpw->pmd, addr);
- goto retry;
- }
- goto out;
- }
-
- page = vm_normal_page(mpw->vma, addr, pte);
- if (!page)
- goto out;
-
- lock_page(page);
- if (!page->mapping) {
- unlock_page(page);
- goto retry;
- }
- munlock_vma_page(page);
- unlock_page(page);
-
-out:
- return 0;
-}
-
-/*
- * Save pmd for pte handler for waiting on migration entries
- */
-static int __munlock_pmd_handler(pmd_t *pmd, unsigned long addr,
- unsigned long end, struct mm_walk *walk)
-{
- struct munlock_page_walk *mpw = walk->private;
-
- mpw->pmd = pmd;
- return 0;
-}
-
-
-/*
- * munlock a range of pages in the vma using standard page table walk.
- *
- * vma->vm_mm->mmap_sem must be held for write.
- */
-static void __munlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
-{
- struct mm_struct *mm = vma->vm_mm;
- struct munlock_page_walk mpw = {
- .vma = vma,
- };
- struct mm_walk munlock_page_walk = {
- .pmd_entry = __munlock_pmd_handler,
- .pte_entry = __munlock_pte_handler,
- .private = &mpw,
- .mm = mm,
- };
-
- VM_BUG_ON(start & ~PAGE_MASK || end & ~PAGE_MASK);
- VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
- VM_BUG_ON(start < vma->vm_start);
- VM_BUG_ON(end > vma->vm_end);
-
- lru_add_drain_all(); /* push cached pages to LRU */
- walk_page_range(start, end, &munlock_page_walk);
- lru_add_drain_all(); /* to update stats */
+ if (retval == -EFAULT)
+ retval = -ENOMEM;
+ else if (retval == -ENOMEM)
+ retval = -EAGAIN;
+ return retval;
}
#else /* CONFIG_UNEVICTABLE_LRU */
/*
* Just make pages present if VM_LOCKED. No-op if unlocking.
*/
-static int __mlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
+static long __mlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end,
+ int mlock)
{
- if (vma->vm_flags & VM_LOCKED)
- make_pages_present(start, end);
+ if (mlock && (vma->vm_flags & VM_LOCKED))
+ return make_pages_present(start, end);
return 0;
}
-/*
- * munlock a range of pages in the vma -- no-op.
- */
-static void __munlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
+static inline int __mlock_posix_error_return(long retval)
{
+ return 0;
}
+
#endif /* CONFIG_UNEVICTABLE_LRU */
-/*
- * mlock all pages in this vma range. For mmap()/mremap()/...
+/**
+ * mlock_vma_pages_range() - mlock pages in specified vma range.
+ * @vma - the vma containing the specfied address range
+ * @start - starting address in @vma to mlock
+ * @end - end address [+1] in @vma to mlock
+ *
+ * For mmap()/mremap()/expansion of mlocked vma.
+ *
+ * return 0 on success for "normal" vmas.
+ *
+ * return number of pages [> 0] to be removed from locked_vm on success
+ * of "special" vmas.
+ *
+ * return negative error if vma spanning @start-@range disappears while
+ * mmap semaphore is dropped. Unlikely?
*/
-int mlock_vma_pages_range(struct vm_area_struct *vma,
+long mlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
+ struct mm_struct *mm = vma->vm_mm;
int nr_pages = (end - start) / PAGE_SIZE;
BUG_ON(!(vma->vm_flags & VM_LOCKED));
if (!((vma->vm_flags & (VM_DONTEXPAND | VM_RESERVED)) ||
is_vm_hugetlb_page(vma) ||
- vma == get_gate_vma(current)))
- return __mlock_vma_pages_range(vma, start, end);
+ vma == get_gate_vma(current))) {
+ long error;
+ downgrade_write(&mm->mmap_sem);
+
+ error = __mlock_vma_pages_range(vma, start, end, 1);
+
+ up_read(&mm->mmap_sem);
+ /* vma can change or disappear */
+ down_write(&mm->mmap_sem);
+ vma = find_vma(mm, start);
+ /* non-NULL vma must contain @start, but need to check @end */
+ if (!vma || end > vma->vm_end)
+ return -ENOMEM;
+
+ return 0; /* hide other errors from mmap(), et al */
+ }
/*
* User mapped kernel pages or huge pages:
no_mlock:
vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */
- return nr_pages; /* pages NOT mlocked */
+ return nr_pages; /* error or pages NOT mlocked */
}
/*
- * munlock all pages in vma. For munmap() and exit().
+ * 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_all(struct vm_area_struct *vma)
+void munlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end)
{
vma->vm_flags &= ~VM_LOCKED;
- __munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
+ __mlock_vma_pages_range(vma, start, end, 0);
}
/*
vma->vm_flags = newflags;
if (lock) {
- ret = __mlock_vma_pages_range(vma, start, end);
- if (ret > 0) {
+ /*
+ * mmap_sem is currently held for write. Downgrade the write
+ * lock to a read lock so that other faults, mmap scans, ...
+ * while we fault in all pages.
+ */
+ downgrade_write(&mm->mmap_sem);
+
+ ret = __mlock_vma_pages_range(vma, start, end, 1);
+
+ /*
+ * Need to reacquire mmap sem in write mode, as our callers
+ * expect this. We have no support for atomically upgrading
+ * a sem to write, so we need to check for ranges while sem
+ * is unlocked.
+ */
+ up_read(&mm->mmap_sem);
+ /* vma can change or disappear */
+ down_write(&mm->mmap_sem);
+ *prev = find_vma(mm, start);
+ /* non-NULL *prev must contain @start, but need to check @end */
+ if (!(*prev) || end > (*prev)->vm_end)
+ ret = -ENOMEM;
+ else if (ret > 0) {
mm->locked_vm -= ret;
ret = 0;
- }
- } else
- __munlock_vma_pages_range(vma, start, end);
+ } else
+ ret = __mlock_posix_error_return(ret); /* translate if needed */
+ } else {
+ /*
+ * TODO: for unlocking, pages will already be resident, so
+ * we don't need to wait for allocations/reclaim/pagein, ...
+ * However, unlocking a very large region can still take a
+ * while. Should we downgrade the semaphore for both lock
+ * AND unlock ?
+ */
+ __mlock_vma_pages_range(vma, start, end, 0);
+ }
out:
*prev = vma;
projects / linux-2.6-omap-h63xx.git / blobdiff