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author | 2014-09-25 09:41:02 +0800 | |
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committer | 2014-09-24 22:16:06 -0400 | |
commit | 2ad654bc5e2b211e92f66da1d819e47d79a866f0 (patch) | |
tree | c638346ac104f054fc61649a8739b004d06aff59 /include/linux/cpuset.h | |
parent | sched: add macros to define bitops for task atomic flags (diff) | |
download | linux-2ad654bc5e2b211e92f66da1d819e47d79a866f0.tar.gz linux-2ad654bc5e2b211e92f66da1d819e47d79a866f0.tar.bz2 linux-2ad654bc5e2b211e92f66da1d819e47d79a866f0.zip |
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:
https://lkml.org/lkml/2014/9/19/230
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 <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time")
Cc: <stable@vger.kernel.org> # 2.6.31+
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/cpuset.h')
-rw-r--r-- | include/linux/cpuset.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index ade2390ffe92..6e39c9bb0dae 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -93,12 +93,12 @@ extern int cpuset_slab_spread_node(void); static inline int cpuset_do_page_mem_spread(void) { - return current->flags & PF_SPREAD_PAGE; + return task_spread_page(current); } static inline int cpuset_do_slab_mem_spread(void) { - return current->flags & PF_SPREAD_SLAB; + return task_spread_slab(current); } extern int current_cpuset_is_being_rebound(void); |