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authorPaul Jackson <pj@sgi.com>2006-01-14 13:21:06 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-14 18:27:10 -0800
commit505970b96e3b7d22177c38e03435a68376628e7a (patch)
tree5508317e391961355bf3d946a6aac05bb21569eb /mm/oom_kill.c
parented68cb3676bb179768529aeb808403d57295af56 (diff)
[PATCH] cpuset oom lock fix
The problem, reported in: http://bugzilla.kernel.org/show_bug.cgi?id=5859 and by various other email messages and lkml posts is that the cpuset hook in the oom (out of memory) code can try to take a cpuset semaphore while holding the tasklist_lock (a spinlock). One must not sleep while holding a spinlock. The fix seems easy enough - move the cpuset semaphore region outside the tasklist_lock region. This required a few lines of mechanism to implement. The oom code where the locking needs to be changed does not have access to the cpuset locks, which are internal to kernel/cpuset.c only. So I provided a couple more cpuset interface routines, available to the rest of the kernel, which simple take and drop the lock needed here (cpusets callback_sem). Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/oom_kill.c')
-rw-r--r--mm/oom_kill.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4748b906aff2..14bd4ec79597 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -274,6 +274,7 @@ void out_of_memory(gfp_t gfp_mask, int order)
show_mem();
}
+ cpuset_lock();
read_lock(&tasklist_lock);
retry:
p = select_bad_process();
@@ -284,6 +285,7 @@ retry:
/* Found nothing?!?! Either we hang forever, or we panic. */
if (!p) {
read_unlock(&tasklist_lock);
+ cpuset_unlock();
panic("Out of memory and no killable processes...\n");
}
@@ -293,6 +295,7 @@ retry:
out:
read_unlock(&tasklist_lock);
+ cpuset_unlock();
if (mm)
mmput(mm);