lkml.org 
[lkml]   [2014]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: frequent lockups in 3.18rc4
On Fri, 14 Nov 2014, Linus Torvalds wrote:
> On Fri, Nov 14, 2014 at 1:31 PM, Dave Jones <davej@redhat.com> wrote:
> > I'm not sure how long this goes back (3.17 was fine afair) but I'm
> > seeing these several times a day lately..
>
> Plus, judging by the fact that there's a stale "leave_mm+0x210/0x210"
> (wouldn't that be the *next* function, namely do_flush_tlb_all())
> pointer on the stack, I suspect that whole range-flushing doesn't even
> trigger, and we are flushing everything.

This stale entry is not relevant here because the thing is stuck in
generic_exec_single().

> > NMI watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [trinity-c129:25570]
> > RIP: 0010:[<ffffffff9c11e98a>] [<ffffffff9c11e98a>] generic_exec_single+0xea/0x1d0

> > Call Trace:
> > [<ffffffff9c048b20>] ? leave_mm+0x210/0x210
> > [<ffffffff9c048b20>] ? leave_mm+0x210/0x210
> > [<ffffffff9c11ead6>] smp_call_function_single+0x66/0x110
> > [<ffffffff9c048b20>] ? leave_mm+0x210/0x210
> > [<ffffffff9c11f021>] smp_call_function_many+0x2f1/0x390
> > [<ffffffff9c049300>] flush_tlb_mm_range+0xe0/0x370

flush_tlb_mm_range()
.....
out:
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, start, end);

which calls

smp_call_function_many() via native_flush_tlb_others()

which is either inlined or not on the stack the invocation of
smp_call_function_many() is a tail call.

So from smp_call_function_many() we end up via
smp_call_function_single() in generic_exec_single().

So the only ways to get stuck there are:

csd_lock(csd);
and
csd_lock_wait(csd);

The called function is flush_tlb_func() and I really can't see why
that would get stuck at all.

So this looks more like a smp function call fuckup.

I assume Dave is running that stuff on KVM. So it might be worth while
to look at the IPI magic there.

Thanks,

tglx



\
 
 \ /
  Last update: 2014-11-15 00:21    [W:0.679 / U:0.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site