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authorMichel Lespinasse <walken@google.com>2011-01-31 17:03:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-02-02 10:20:50 +1100
commitfdf4c587a793ba87935e38e7f25a9540bc9a7b95 (patch)
treec134f1772c46e2c5214550aaf08c58b36d755a55 /mm
parent69bc70d4f97ce82153bed0afc9f432700c60390b (diff)
downloadlinux-linaro-stable-fdf4c587a793ba87935e38e7f25a9540bc9a7b95.tar.gz
mlock: operate on any regions with protection != PROT_NONE
As Tao Ma noticed, change 5ecfda0 breaks blktrace. This is because blktrace mmaps a file with PROT_WRITE permissions but without PROT_READ, so my attempt to not unnecessarity break COW during mlock ended up causing mlock to fail with a permission problem. I am proposing to let mlock ignore vma protection in all cases except PROT_NONE. In particular, mlock should not fail for PROT_WRITE regions (as in the blktrace case, which broke at 5ecfda0) or for PROT_EXEC regions (which seem to me like they were always broken). Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mlock.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index 13e81ee8be9d..c3924c7f00be 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -178,6 +178,13 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
gup_flags |= FOLL_WRITE;
+ /*
+ * We want mlock to succeed for regions that have any permissions
+ * other than PROT_NONE.
+ */
+ if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
+ gup_flags |= FOLL_FORCE;
+
if (vma->vm_flags & VM_LOCKED)
gup_flags |= FOLL_MLOCK;