diff options
| author | Michel Lespinasse <walken@google.com> | 2011-01-31 17:03:41 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-02-02 10:20:50 +1100 |
| commit | fdf4c587a793ba87935e38e7f25a9540bc9a7b95 (patch) | |
| tree | c134f1772c46e2c5214550aaf08c58b36d755a55 /mm | |
| parent | 69bc70d4f97ce82153bed0afc9f432700c60390b (diff) | |
| download | lwn-fdf4c587a793ba87935e38e7f25a9540bc9a7b95.tar.gz lwn-fdf4c587a793ba87935e38e7f25a9540bc9a7b95.zip | |
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.c | 7 |
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; |