Re: mm: mmap_sem lock assertion failure in __mlock_vma_pages_range

[Davidlohr Bueso]

On Tue, 2014-03-11 at 17:02 -0400, Sasha Levin wrote:
> On 03/11/2014 04:47 PM, Davidlohr Bueso wrote:
> >> Bingo! With the above patch:
> >> >
> >> >[  243.565794] kernel BUG at mm/vmacache.c:76!
> >> >[  243.566720] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> >> >[  243.568048] Dumping ftrace buffer:
> >> >[  243.568740]    (ftrace buffer empty)
> >> >[  243.569481] Modules linked in:
> >> >[  243.570203] CPU: 10 PID: 10073 Comm: trinity-c332 Tainted: G        W    3.14.0-rc5-next-20140307-sasha-00010-g1f812cb-dirty #143
> > and this is also part of the DEBUG_PAGEALLOC + trinity combo! I suspect
> > the root cause it the same as Fengguang's report.
> 
> The BUG still happens without DEBUG_PAGEALLOC.

Any idea what trinity itself is doing?

Could you add the following, I just want to make sure the bug isn't
being caused by an overflow:

diff --git a/mm/vmacache.c b/mm/vmacache.c
index add3162..abb85cc 100644
--- a/mm/vmacache.c
+++ b/mm/vmacache.c
@@ -17,6 +17,8 @@ void vmacache_flush_all(struct mm_struct *mm)
 {
        struct task_struct *g, *p;
 
+       WARN_ON_ONCE(1);
+
        rcu_read_lock();
        for_each_process_thread(g, p) {
                /*


Thanks.

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