Messages in this thread | | | Date | Fri, 16 Jan 2015 12:00:07 -0500 | From | Chris Mason <> | Subject | Re: Linux 3.19-rc3 |
| |
On Fri, Jan 16, 2015 at 11:56 AM, Peter Hurley <peter@hurleysoftware.com> wrote: > On 01/06/2015 06:07 AM, Kent Overstreet wrote: >> On Tue, Jan 06, 2015 at 12:01:12PM +0100, Peter Zijlstra wrote: >>> On Tue, Jan 06, 2015 at 11:18:04AM +0100, Sedat Dilek wrote: >>>> On Tue, Jan 6, 2015 at 11:06 AM, Peter Zijlstra >>>> <peterz@infradead.org> wrote: >>>>> On Tue, Jan 06, 2015 at 10:57:19AM +0100, Sedat Dilek wrote: >>>>>> [ 88.028739] [<ffffffff8124433f>] aio_read_events+0x4f/0x2d0 >>>>>> >>>>> >>>>> Ah, that one. Chris Mason and Kent Overstreet were looking at >>>>> that one. >>>>> I'm not touching the AIO code either ;-) >>>> >>>> I know, I was so excited when I see nearly the same output. >>>> >>>> Can you tell me why people see "similiar" problems in different >>>> areas? >>> >>> Because the debug check is new :-) It's a pattern that should not >>> be >>> used but mostly works most of the times. >>> >>>> [ 181.397024] WARNING: CPU: 0 PID: 2872 at >>>> kernel/sched/core.c:7303 >>>> __might_sleep+0xbd/0xd0() >>>> [ 181.397028] do not call blocking ops when !TASK_RUNNING; >>>> state=1 >>>> set at [<ffffffff810b83bd>] prepare_to_wait_event+0x5d/0x110 >>>> >>>> With similiar buzzwords... namely... >>>> >>>> mutex_lock_nested >>>> prepare_to_wait(_event) >>>> __might_sleep >>>> >>>> I am asking myself... Where is the real root cause - in >>>> sched/core? >>>> Fix one single place VS. fix the impact at several other places? >>> >>> No, the root cause is nesting sleep primitives, this is not >>> fixable in >>> the one place, both prepare_to_wait and mutex_lock are using >>> task_struct::state, they have to, no way around it. >> >> No, it's completely possible to construct a prepare_to_wait() that >> doesn't >> require messing with the task state. Had it for years. >> >> >> https://urldefense.proofpoint.com/v1/url?u=http://evilpiepirate.org/git/linux-bcache.git/log/?h%3Daio_ring_fix&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=6%2FL0lzzDhu0Y1hL9xm%2BQyA%3D%3D%0A&m=QKQw1WQ3qeio%2FM623F%2BN1X1PeHp7PLLjdIQdHnHU5qo%3D%0A&s=b4e94a6a4b0922e356cadd19f6b22862dbd258fa11c2f26c3d7d76dcac1963ce > > Peter & Kent, > > What's the plan here?
I'm cleaning up my patch slightly and resubmitting.
-chris
| |