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 | |
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]
-rw-r--r-- | Documentation/cgroups/cpusets.txt | 6 | ||||
-rw-r--r-- | include/linux/cpuset.h | 4 | ||||
-rw-r--r-- | include/linux/sched.h | 12 | ||||
-rw-r--r-- | kernel/cpuset.c | 9 | ||||
-rw-r--r-- | mm/slab.c | 4 |
5 files changed, 22 insertions, 13 deletions
diff --git a/Documentation/cgroups/cpusets.txt b/Documentation/cgroups/cpusets.txt index cefd3d8bbd11..a52a39f8a8d4 100644 --- a/Documentation/cgroups/cpusets.txt +++ b/Documentation/cgroups/cpusets.txt @@ -345,14 +345,14 @@ the named feature on. The implementation is simple. Setting the flag 'cpuset.memory_spread_page' turns on a per-process flag -PF_SPREAD_PAGE for each task that is in that cpuset or subsequently +PFA_SPREAD_PAGE for each task that is in that cpuset or subsequently joins that cpuset. The page allocation calls for the page cache -is modified to perform an inline check for this PF_SPREAD_PAGE task +is modified to perform an inline check for this PFA_SPREAD_PAGE task flag, and if set, a call to a new routine cpuset_mem_spread_node() returns the node to prefer for the allocation. Similarly, setting 'cpuset.memory_spread_slab' turns on the flag -PF_SPREAD_SLAB, and appropriately marked slab caches will allocate +PFA_SPREAD_SLAB, and appropriately marked slab caches will allocate pages from the node returned by cpuset_mem_spread_node(). The cpuset_mem_spread_node() routine is also simple. It uses the diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 668f66baac7b..bb48be7994c1 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -74,12 +74,12 @@ 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 b85b71963e88..56d8233c5de7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1834,8 +1834,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * #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_THREAD_BOUND 0x04000000 /* Thread bound to specific cpu */ #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ #define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */ @@ -1868,6 +1866,8 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * #define used_math() tsk_used_math(current) /* Per-process atomic flags. */ +#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) \ @@ -1970,6 +1970,14 @@ static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask) } #endif +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) + /* * Do not use outside of architecture code which knows its limitations. * 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); } /* diff --git a/mm/slab.c b/mm/slab.c index 3eb1c38e2c30..3714dd9c5877 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3321,7 +3321,7 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags) #ifdef CONFIG_NUMA /* - * Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY. + * Try allocating on another node if PFA_SPREAD_SLAB|PF_MEMPOLICY. * * If we are in_interrupt, then process context, including cpusets and * mempolicy, may not apply and should not be used for allocation policy. @@ -3562,7 +3562,7 @@ __do_cache_alloc(struct kmem_cache *cache, gfp_t flags) { void *objp; - if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) { + if (unlikely((current->flags & PF_MEMPOLICY) || cpuset_do_slab_mem_spread())) { objp = alternate_node_alloc(cache, flags); if (objp) goto out; |