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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.
Change-Id: I4eef89f5d91eaa2e7e677e662133a7856909a13f
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: 950592f7b9
("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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
parent
cb1a9b6a01
commit
bbc314da7d
5 changed files with 23 additions and 13 deletions
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@ -345,14 +345,14 @@ the named feature on.
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The implementation is simple.
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Setting the flag 'cpuset.memory_spread_page' turns on a per-process flag
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PF_SPREAD_PAGE for each task that is in that cpuset or subsequently
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PFA_SPREAD_PAGE for each task that is in that cpuset or subsequently
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joins that cpuset. The page allocation calls for the page cache
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is modified to perform an inline check for this PF_SPREAD_PAGE task
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is modified to perform an inline check for this PFA_SPREAD_PAGE task
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flag, and if set, a call to a new routine cpuset_mem_spread_node()
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returns the node to prefer for the allocation.
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Similarly, setting 'cpuset.memory_spread_slab' turns on the flag
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PF_SPREAD_SLAB, and appropriately marked slab caches will allocate
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PFA_SPREAD_SLAB, and appropriately marked slab caches will allocate
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pages from the node returned by cpuset_mem_spread_node().
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The cpuset_mem_spread_node() routine is also simple. It uses the
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@ -72,12 +72,12 @@ extern int cpuset_slab_spread_node(void);
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static inline int cpuset_do_page_mem_spread(void)
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{
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return current->flags & PF_SPREAD_PAGE;
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return task_spread_page(current);
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}
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static inline int cpuset_do_slab_mem_spread(void)
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{
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return current->flags & PF_SPREAD_SLAB;
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return task_spread_slab(current);
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}
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extern int current_cpuset_is_being_rebound(void);
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@ -1861,8 +1861,6 @@ static inline void sched_set_io_is_busy(int val) {};
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#define PF_KTHREAD 0x00200000 /* I am a kernel thread */
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#define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */
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#define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */
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#define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */
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#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */
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#define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_allowed */
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#define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */
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#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
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@ -1921,6 +1919,9 @@ static inline void memalloc_noio_restore(unsigned int flags)
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/* Per-process atomic flags. */
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#define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges. */
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#define PFA_SPREAD_PAGE 1 /* Spread page cache over cpuset */
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#define PFA_SPREAD_SLAB 2 /* Spread some slab caches over cpuset */
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#define TASK_PFA_TEST(name, func) \
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static inline bool task_##func(struct task_struct *p) \
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@ -1935,6 +1936,14 @@ static inline void memalloc_noio_restore(unsigned int flags)
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TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
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TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
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TASK_PFA_TEST(SPREAD_PAGE, spread_page)
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TASK_PFA_SET(SPREAD_PAGE, spread_page)
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TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)
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TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
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TASK_PFA_SET(SPREAD_SLAB, spread_slab)
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TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
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/*
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* task->jobctl flags
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*/
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@ -363,13 +363,14 @@ static void cpuset_update_task_spread_flag(struct cpuset *cs,
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struct task_struct *tsk)
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{
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if (is_spread_page(cs))
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tsk->flags |= PF_SPREAD_PAGE;
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task_set_spread_page(tsk);
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else
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tsk->flags &= ~PF_SPREAD_PAGE;
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task_clear_spread_page(tsk);
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if (is_spread_slab(cs))
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tsk->flags |= PF_SPREAD_SLAB;
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task_set_spread_slab(tsk);
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else
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tsk->flags &= ~PF_SPREAD_SLAB;
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task_clear_spread_slab(tsk);
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}
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/*
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@ -3168,7 +3168,7 @@ out:
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#ifdef CONFIG_NUMA
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/*
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* Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY.
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* Try allocating on another node if PFA_SPREAD_SLAB|PF_MEMPOLICY.
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*
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* If we are in_interrupt, then process context, including cpusets and
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* mempolicy, may not apply and should not be used for allocation policy.
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@ -3412,7 +3412,7 @@ __do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
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{
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void *objp;
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if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
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if (unlikely((current->flags & PF_MEMPOLICY) || cpuset_do_slab_mem_spread())) {
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objp = alternate_node_alloc(cache, flags);
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if (objp)
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goto out;
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