1 files changed, 49 insertions, 79 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index c9bd528b01d2..79b7cf7d1bca 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -102,13 +102,16 @@ void mlock_vma_page(struct page *page)
  * can't isolate the page, we leave it for putback_lru_page() and vmscan
  * [page_referenced()/try_to_unmap()] to deal with.
  */
-void munlock_vma_page(struct page *page)
+unsigned int munlock_vma_page(struct page *page)
 {
+        unsigned int page_mask = 0;
+
         BUG_ON(!PageLocked(page));
 
         if (TestClearPageMlocked(page)) {
-                mod_zone_page_state(page_zone(page), NR_MLOCK,
-                                    -hpage_nr_pages(page));
+                unsigned int nr_pages = hpage_nr_pages(page);
+                mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
+                page_mask = nr_pages - 1;
                 if (!isolate_lru_page(page)) {
                         int ret = SWAP_AGAIN;
 
@@ -141,6 +144,8 @@ void munlock_vma_page(struct page *page)
                                 count_vm_event(UNEVICTABLE_PGMUNLOCKED);
                 }
         }
+
+        return page_mask;
 }
 
 /**
@@ -155,13 +160,11 @@ void munlock_vma_page(struct page *page)
  *
  * vma->vm_mm->mmap_sem must be held for at least read.
  */
-static long __mlock_vma_pages_range(struct vm_area_struct *vma,
-                                    unsigned long start, unsigned long end,
-                                    int *nonblocking)
+long __mlock_vma_pages_range(struct vm_area_struct *vma,
+                unsigned long start, unsigned long end, int *nonblocking)
 {
         struct mm_struct *mm = vma->vm_mm;
-        unsigned long addr = start;
-        int nr_pages = (end - start) / PAGE_SIZE;
+        unsigned long nr_pages = (end - start) / PAGE_SIZE;
         int gup_flags;
 
         VM_BUG_ON(start & ~PAGE_MASK);
@@ -186,7 +189,11 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
         if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
                 gup_flags |= FOLL_FORCE;
 
-        return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
+        /*
+         * We made sure addr is within a VMA, so the following will
+         * not result in a stack expansion that recurses back here.
+         */
+        return __get_user_pages(current, mm, start, nr_pages, gup_flags,
                                 NULL, NULL, nonblocking);
 }
 
@@ -202,56 +209,6 @@ static int __mlock_posix_error_return(long retval)
         return retval;
 }
 
-/**
- * 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.
- */
-long mlock_vma_pages_range(struct vm_area_struct *vma,
-                        unsigned long start, unsigned long end)
-{
-        int nr_pages = (end - start) / PAGE_SIZE;
-        BUG_ON(!(vma->vm_flags & VM_LOCKED));
-
-        /*
-         * filter unlockable vmas
-         */
-        if (vma->vm_flags & (VM_IO | VM_PFNMAP))
-                goto no_mlock;
-
-        if (!((vma->vm_flags & VM_DONTEXPAND) ||
-                        is_vm_hugetlb_page(vma) ||
-                        vma == get_gate_vma(current->mm))) {
-
-                __mlock_vma_pages_range(vma, start, end, NULL);
-
-                /* Hide errors from mmap() and other callers */
-                return 0;
-        }
-
-        /*
-         * User mapped kernel pages or huge pages:
-         * make these pages present to populate the ptes, but
-         * fall thru' to reset VM_LOCKED--no need to unlock, and
-         * return nr_pages so these don't get counted against task's
-         * locked limit.  huge pages are already counted against
-         * locked vm limit.
-         */
-        make_pages_present(start, end);
-
-no_mlock:
-        vma->vm_flags &= ~VM_LOCKED;    /* and don't come back! */
-        return nr_pages;                /* error or pages NOT mlocked */
-}
-
 /*
  * munlock_vma_pages_range() - munlock all pages in the vma range.'
  * @vma - vma containing range to be munlock()ed.
@@ -273,13 +230,12 @@ no_mlock:
 void munlock_vma_pages_range(struct vm_area_struct *vma,
                              unsigned long start, unsigned long end)
 {
-        unsigned long addr;
-
-        lru_add_drain();
         vma->vm_flags &= ~VM_LOCKED;
 
-        for (addr = start; addr < end; addr += PAGE_SIZE) {
+        while (start < end) {
                 struct page *page;
+                unsigned int page_mask, page_increm;
+
                 /*
                  * Although FOLL_DUMP is intended for get_dump_page(),
                  * it just so happens that its special treatment of the
@@ -287,13 +243,22 @@ void munlock_vma_pages_range(struct vm_area_struct *vma,
                  * 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, addr, FOLL_GET | FOLL_DUMP);
+                page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP,
+                                        &page_mask);
                 if (page && !IS_ERR(page)) {
                         lock_page(page);
-                        munlock_vma_page(page);
+                        lru_add_drain();
+                        /*
+                         * Any THP page found by follow_page_mask() may have
+                         * gotten split before reaching munlock_vma_page(),
+                         * so we need to recompute the page_mask here.
+                         */
+                        page_mask = munlock_vma_page(page);
                         unlock_page(page);
                         put_page(page);
                 }
+                page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
+                start += page_increm * PAGE_SIZE;
                 cond_resched();
         }
 }
@@ -303,7 +268,7 @@ void munlock_vma_pages_range(struct vm_area_struct *vma,
  *
  * 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 via make_pages_present().
+ * populate the ptes.
  *
  * For vmas that pass the filters, merge/split as appropriate.
  */
@@ -391,9 +356,9 @@ static int do_mlock(unsigned long start, size_t len, int on)
 
                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
 
-                newflags = vma->vm_flags | VM_LOCKED;
-                if (!on)
-                        newflags &= ~VM_LOCKED;
+                newflags = vma->vm_flags & ~VM_LOCKED;
+                if (on)
+                        newflags |= VM_LOCKED;
 
                 tmp = vma->vm_end;
                 if (tmp > end)
@@ -416,13 +381,20 @@ static int do_mlock(unsigned long start, size_t len, int on)
         return error;
 }
 
-static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
 {
         struct mm_struct *mm = current->mm;
         unsigned long end, nstart, nend;
         struct vm_area_struct *vma = NULL;
         int locked = 0;
-        int ret = 0;
+        long ret = 0;
 
         VM_BUG_ON(start & ~PAGE_MASK);
         VM_BUG_ON(len != PAGE_ALIGN(len));
@@ -498,7 +470,7 @@ SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
                 error = do_mlock(start, len, 1);
         up_write(&current->mm->mmap_sem);
         if (!error)
-                error = do_mlock_pages(start, len, 0);
+                error = __mm_populate(start, len, 0);
         return error;
 }
 
@@ -528,9 +500,9 @@ static int do_mlockall(int flags)
         for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
                 vm_flags_t newflags;
 
-                newflags = vma->vm_flags | VM_LOCKED;
-                if (!(flags & MCL_CURRENT))
-                        newflags &= ~VM_LOCKED;
+                newflags = vma->vm_flags & ~VM_LOCKED;
+                if (flags & MCL_CURRENT)
+                        newflags |= VM_LOCKED;
 
                 /* Ignore errors */
                 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
@@ -564,10 +536,8 @@ SYSCALL_DEFINE1(mlockall, int, flags)
             capable(CAP_IPC_LOCK))
                 ret = do_mlockall(flags);
         up_write(&current->mm->mmap_sem);
-        if (!ret && (flags & MCL_CURRENT)) {
-                /* Ignore errors */
-                do_mlock_pages(0, TASK_SIZE, 1);
-        }
+        if (!ret && (flags & MCL_CURRENT))
+                mm_populate(0, TASK_SIZE);
 out:
         return ret;
 }