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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:
|
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|---|---|---|
| .. | ||
| 00-INDEX | ||
| blkio-controller.txt | ||
| cgroups.txt | ||
| cpuacct.txt | ||
| cpusets.txt | ||
| devices.txt | ||
| freezer-subsystem.txt | ||
| hugetlb.txt | ||
| memcg_test.txt | ||
| memory.txt | ||
| net_cls.txt | ||
| net_prio.txt | ||
| resource_counter.txt | ||
| unified-hierarchy.txt | ||