path: root/mm
diff options
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-09-24 18:29:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-24 19:44:40 -0700
commit22356f447ceb8d97a4885792e7d9e4607f712e1b (patch)
tree5d19a3ce69f94a92e0e303054f9ed44a826b8b19 /mm
parenta153e67bda3639a46edac6205610ae63c0fdea4c (diff)
mm: Place preemption point in do_mlockall() loop
There is a loop in do_mlockall() that lacks a preemption point, which means that the following can happen on non-preemptible builds of the kernel. Dave Jones reports: "My fuzz tester keeps hitting this. Every instance shows the non-irq stack came in from mlockall. I'm only seeing this on one box, but that has more ram (8gb) than my other machines, which might explain it. INFO: rcu_preempt self-detected stall on CPU { 3} (t=6500 jiffies g=470344 c=470343 q=0) sending NMI to all CPUs: NMI backtrace for cpu 3 CPU: 3 PID: 29664 Comm: trinity-child2 Not tainted 3.11.0-rc1+ #32 Call Trace: lru_add_drain_all+0x15/0x20 SyS_mlockall+0xa5/0x1a0 tracesys+0xdd/0xe2" This commit addresses this problem by inserting the required preemption point. Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Michel Lespinasse <walken@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index d63802663242..67ba6da7d0e3 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -736,6 +736,7 @@ static int do_mlockall(int flags)
/* Ignore errors */
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
+ cond_resched();
return 0;