path: root/mm
diff options
authorZefan Li <>2014-09-25 09:41:02 +0800
committerTejun Heo <>2014-09-24 22:16:06 -0400
commit2ad654bc5e2b211e92f66da1d819e47d79a866f0 (patch)
treec638346ac104f054fc61649a8739b004d06aff59 /mm
parente0e5070b20e01f0321f97db4e4e174f3f6b49e50 (diff)
cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags
When we change cpuset.memory_spread_{page,slab}, cpuset will flip PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset. This should be done using atomic bitops, but currently we don't, which is broken. Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happened when one thread tried to clear PF_USED_MATH while at the same time another thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on the same task. Here's the full report: To fix this, we make PF_SPREAD_PAGE and PF_SPREAD_SLAB atomic flags. v4: - updated mm/slab.c. (Fengguang Wu) - updated Documentation. Cc: Peter Zijlstra <> Cc: Ingo Molnar <> Cc: Miao Xie <> Cc: Kees Cook <> Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time") Cc: <> # 2.6.31+ Reported-by: Tetsuo Handa <> Signed-off-by: Zefan Li <> Signed-off-by: Tejun Heo <>
Diffstat (limited to 'mm')
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c
index a467b308c682..881951e67f12 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2994,7 +2994,7 @@ out:
- * Try allocating on another node if PF_SPREAD_SLAB is a mempolicy is set.
+ * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
* If we are in_interrupt, then process context, including cpusets and
* mempolicy, may not apply and should not be used for allocation policy.
@@ -3226,7 +3226,7 @@ __do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
void *objp;
- if (current->mempolicy || unlikely(current->flags & PF_SPREAD_SLAB)) {
+ if (current->mempolicy || cpuset_do_slab_mem_spread()) {
objp = alternate_node_alloc(cache, flags);
if (objp)
goto out;