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| author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-06-23 12:36:58 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-23 12:50:05 -0700 |
| commit | a5c9b696ec109bb54d547fdb437a7a0c2d514670 (patch) | |
| tree | c97533e38359a2e731bcc2c65f063a27f4f629e6 /mm/memory.c | |
| parent | 626f380d0b264a1e40237f5a2a3dffc5d14f256e (diff) | |
| download | lwn-a5c9b696ec109bb54d547fdb437a7a0c2d514670.tar.gz lwn-a5c9b696ec109bb54d547fdb437a7a0c2d514670.zip | |
mm: pass mm to grab_swap_token
If a kthread happens to use get_user_pages() on an mm (as KSM does),
there's a chance that it will end up trying to read in a swap page, then
oops in grab_swap_token() because the kthread has no mm: GUP passes down
the right mm, so grab_swap_token() ought to be using it.
We have not identified a stronger case than KSM's daemon (not yet in
mainline), but the issue must have come up before, since RHEL has included
a fix for this for years (though a different fix, they just back out of
grab_swap_token if current->mm is unset: which is what we first proposed,
but using the right mm here seems more correct).
Reported-by: Izik Eidus <ieidus@redhat.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c index 50da9511aa77..f46ac18ba231 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2519,7 +2519,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, delayacct_set_flag(DELAYACCT_PF_SWAPIN); page = lookup_swap_cache(entry); if (!page) { - grab_swap_token(); /* Contend for token _before_ read-in */ + grab_swap_token(mm); /* Contend for token _before_ read-in */ page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma, address); if (!page) { |