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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-09-25 01:29:11 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-25 02:44:40 (GMT) |
commit | 22356f447ceb8d97a4885792e7d9e4607f712e1b (patch) | |
tree | 5d19a3ce69f94a92e0e303054f9ed44a826b8b19 | |
parent | a153e67bda3639a46edac6205610ae63c0fdea4c (diff) | |
download | linux-22356f447ceb8d97a4885792e7d9e4607f712e1b.tar.xz |
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>
-rw-r--r-- | mm/mlock.c | 1 |
1 files changed, 1 insertions, 0 deletions
@@ -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(); } out: return 0; |