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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 /include/linux/swap.h | |
| parent | 626f380d0b264a1e40237f5a2a3dffc5d14f256e (diff) | |
| download | op-kernel-dev-a5c9b696ec109bb54d547fdb437a7a0c2d514670.zip op-kernel-dev-a5c9b696ec109bb54d547fdb437a7a0c2d514670.tar.gz | |
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 'include/linux/swap.h')
| -rw-r--r-- | include/linux/swap.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index c88b366..7c15334 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -298,8 +298,8 @@ extern int try_to_free_swap(struct page *); struct backing_dev_info; /* linux/mm/thrash.c */ -extern struct mm_struct * swap_token_mm; -extern void grab_swap_token(void); +extern struct mm_struct *swap_token_mm; +extern void grab_swap_token(struct mm_struct *); extern void __put_swap_token(struct mm_struct *); static inline int has_swap_token(struct mm_struct *mm) @@ -419,10 +419,10 @@ static inline swp_entry_t get_swap_page(void) } /* linux/mm/thrash.c */ -#define put_swap_token(x) do { } while(0) -#define grab_swap_token() do { } while(0) -#define has_swap_token(x) 0 -#define disable_swap_token() do { } while(0) +#define put_swap_token(mm) do { } while (0) +#define grab_swap_token(mm) do { } while (0) +#define has_swap_token(mm) 0 +#define disable_swap_token() do { } while (0) static inline void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) |
