diff options
| author | Christoph Lameter <cl@linux.com> | 2011-05-16 15:26:08 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-06-03 09:32:13 +0900 |
| commit | 440316e6310c2ce372e32d12c83ccc8ddcfb5028 (patch) | |
| tree | 2257e1a84a1286727a2b619bcf2d2336f5f22a85 | |
| parent | 22d82c7586eb492067805dd781f84f5a94133357 (diff) | |
slub: Make CONFIG_DEBUG_PAGE_ALLOC work with new fastpath
commit 1393d9a1857471f816d0be1ccc1d6433a86050f6 upstream.
Fastpath can do a speculative access to a page that CONFIG_DEBUG_PAGE_ALLOC may have
marked as invalid to retrieve the pointer to the next free object.
Use probe_kernel_read in that case in order not to cause a page fault.
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | mm/slub.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/slub.c b/mm/slub.c index 9d2e5e46bf0..f6cb6cd69fc 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -261,6 +261,18 @@ static inline void *get_freepointer(struct kmem_cache *s, void *object) return *(void **)(object + s->offset); } +static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) +{ + void *p; + +#ifdef CONFIG_DEBUG_PAGEALLOC + probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p)); +#else + p = get_freepointer(s, object); +#endif + return p; +} + static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) { *(void **)(object + s->offset) = fp; @@ -1943,7 +1955,7 @@ redo: if (unlikely(!irqsafe_cpu_cmpxchg_double( s->cpu_slab->freelist, s->cpu_slab->tid, object, tid, - get_freepointer(s, object), next_tid(tid)))) { + get_freepointer_safe(s, object), next_tid(tid)))) { note_cmpxchg_failure("slab_alloc", s, tid); goto redo; |