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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 /include
parente0e5070b20e01f0321f97db4e4e174f3f6b49e50 (diff)
downloadlinux-linaro-stable-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 'include')
-rw-r--r--include/linux/cpuset.h4
-rw-r--r--include/linux/sched.h13
2 files changed, 13 insertions, 4 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);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5630763956d9..7b1cafefb05e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1903,8 +1903,6 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
#define PF_KTHREAD 0x00200000 /* I am a kernel thread */
#define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */
#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */
-#define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */
-#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */
#define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */
#define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
@@ -1958,6 +1956,9 @@ static inline void memalloc_noio_restore(unsigned int flags)
/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges. */
+#define PFA_SPREAD_PAGE 1 /* Spread page cache over cpuset */
+#define PFA_SPREAD_SLAB 2 /* Spread some slab caches over cpuset */
+
#define TASK_PFA_TEST(name, func) \
static inline bool task_##func(struct task_struct *p) \
@@ -1972,6 +1973,14 @@ static inline void memalloc_noio_restore(unsigned int flags)
TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
+TASK_PFA_TEST(SPREAD_PAGE, spread_page)
+TASK_PFA_SET(SPREAD_PAGE, spread_page)
+TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)
+
+TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
+TASK_PFA_SET(SPREAD_SLAB, spread_slab)
+TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
+
/*
* task->jobctl flags
*/