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authorZefan Li <lizefan@huawei.com>2014-09-25 09:41:02 +0800
committerTejun Heo <tj@kernel.org>2014-09-24 22:16:06 -0400
commit2ad654bc5e2b211e92f66da1d819e47d79a866f0 (patch)
treec638346ac104f054fc61649a8739b004d06aff59 /arch
parente0e5070b20e01f0321f97db4e4e174f3f6b49e50 (diff)
downloadlinux-2ad654bc5e2b211e92f66da1d819e47d79a866f0.tar.gz
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 'arch')
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