diff options
| author | Christoph Lameter <cl@linux.com> | 2011-05-16 15:26:08 -0500 |
|---|---|---|
| committer | Pekka Enberg <penberg@kernel.org> | 2011-05-17 22:18:55 +0300 |
| commit | 1393d9a1857471f816d0be1ccc1d6433a86050f6 (patch) | |
| tree | 2bcad46d15f1dc7ea6e458f2ab4d7f17b766dd66 | |
| parent | 6332aa9d25e911cc97aa9cc09acee21afda07ea6 (diff) | |
slub: Make CONFIG_DEBUG_PAGE_ALLOC work with new fastpath
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.
Cc: <stable@kernel.org> # 38.x
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>
| -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 8657ab838b8..97bb5b8d935 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; @@ -1933,7 +1945,7 @@ redo: if (unlikely(!this_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; |