diff options
| author | Mel Gorman <mgorman@suse.de> | 2012-12-21 23:10:25 +0000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-01-02 17:32:13 -0800 |
| commit | 42288fe366c4f1ce7522bc9f27d0bc2a81c55264 (patch) | |
| tree | f881ebd4f4032e6cc8f5f848b2e61e9ff1d611af /include/linux | |
| parent | 5439ca6b8ff8cf8d758c19eb28b617a5912904ee (diff) | |
mm: mempolicy: Convert shared_policy mutex to spinlock
Sasha was fuzzing with trinity and reported the following problem:
BUG: sleeping function called from invalid context at kernel/mutex.c:269
in_atomic(): 1, irqs_disabled(): 0, pid: 6361, name: trinity-main
2 locks held by trinity-main/6361:
#0: (&mm->mmap_sem){++++++}, at: [<ffffffff810aa314>] __do_page_fault+0x1e4/0x4f0
#1: (&(&mm->page_table_lock)->rlock){+.+...}, at: [<ffffffff8122f017>] handle_pte_fault+0x3f7/0x6a0
Pid: 6361, comm: trinity-main Tainted: G W
3.7.0-rc2-next-20121024-sasha-00001-gd95ef01-dirty #74
Call Trace:
__might_sleep+0x1c3/0x1e0
mutex_lock_nested+0x29/0x50
mpol_shared_policy_lookup+0x2e/0x90
shmem_get_policy+0x2e/0x30
get_vma_policy+0x5a/0xa0
mpol_misplaced+0x41/0x1d0
handle_pte_fault+0x465/0x6a0
This was triggered by a different version of automatic NUMA balancing
but in theory the current version is vunerable to the same problem.
do_numa_page
-> numa_migrate_prep
-> mpol_misplaced
-> get_vma_policy
-> shmem_get_policy
It's very unlikely this will happen as shared pages are not marked
pte_numa -- see the page_mapcount() check in change_pte_range() -- but
it is possible.
To address this, this patch restores sp->lock as originally implemented
by Kosaki Motohiro. In the path where get_vma_policy() is called, it
should not be calling sp_alloc() so it is not necessary to treat the PTL
specially.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mempolicy.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h index 92bc9988a180..0d7df39a5885 100644 --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -123,7 +123,7 @@ struct sp_node { struct shared_policy { struct rb_root root; - struct mutex mutex; + spinlock_t lock; }; void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol); |