diff options
| author | Zefan Li <lizefan@huawei.com> | 2014-09-25 09:41:02 +0800 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2014-12-01 18:02:38 +0800 |
| commit | 4fae6ccac642aa30d189dea30ef14306aad4d2d2 (patch) | |
| tree | f4277880c2438c5ef039b4a88d818555150799f9 /kernel | |
| parent | 699c06b386d592bede77d5a28ed1637c80ab99c0 (diff) | |
cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags
commit 2ad654bc5e2b211e92f66da1d819e47d79a866f0 upstream.
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")
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>
[lizf: Backported to 3.4:
- adjust context
- check current->flags & PF_MEMPOLICY rather than current->mempolicy]
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpuset.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 9cb82b9aeb73..7f3bde5c50fe 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -326,13 +326,14 @@ static void cpuset_update_task_spread_flag(struct cpuset *cs, struct task_struct *tsk) { if (is_spread_page(cs)) - tsk->flags |= PF_SPREAD_PAGE; + task_set_spread_page(tsk); else - tsk->flags &= ~PF_SPREAD_PAGE; + task_clear_spread_page(tsk); + if (is_spread_slab(cs)) - tsk->flags |= PF_SPREAD_SLAB; + task_set_spread_slab(tsk); else - tsk->flags &= ~PF_SPREAD_SLAB; + task_clear_spread_slab(tsk); } /* |