Messages in this thread | | | Date | Tue, 1 Jun 2010 09:53:45 +0200 | From | Jens Axboe <> | Subject | Re: BUG: using smp_processor_id() in preemptible [00000000] code: icedove-bin/5449 |
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On Tue, Jun 01 2010, Ingo Molnar wrote: > > * Jens Axboe <axboe@kernel.dk> wrote: > > > On Tue, Jun 01 2010, Ingo Molnar wrote: > > > > > > * Peter Zijlstra <peterz@infradead.org> wrote: > > > > > > > On Mon, 2010-05-24 at 05:03 +0200, Piotr Hosowicz wrote: > > > > > [ 720.313607] BUG: using smp_processor_id() in preemptible [00000000] code: icedove-bin/5449 > > > > > [ 720.313612] caller is native_sched_clock+0x3c/0x68 > > > > > [ 720.313616] Pid: 5449, comm: icedove-bin Tainted: P 2.6.34-20100524-0407 #1 > > > > > [ 720.313618] Call Trace: > > > > > [ 720.313624] [<ffffffff811a533b>] debug_smp_processor_id+0xc7/0xe0 > > > > > [ 720.313629] [<ffffffff81009b87>] native_sched_clock+0x3c/0x68 > > > > > [ 720.313634] [<ffffffff81009a4d>] sched_clock+0x9/0xd > > > > > [ 720.313637] [<ffffffff811823ec>] blk_rq_init+0x92/0x9d > > > > > [ 720.313641] [<ffffffff81184227>] get_request+0x1bf/0x2c7 > > > > > [ 720.313646] [<ffffffff8118435c>] get_request_wait+0x2d/0x19d > > > > > > > > This comes from wreckage in the blk tree.. > > > > > > > > --- > > > > commit 9195291e5f05e01d67f9a09c756b8aca8f009089 > > > > Author: Divyesh Shah <dpshah@google.com> > > > > Date: Thu Apr 1 15:01:41 2010 -0700 > > > > > > > > blkio: Increment the blkio cgroup stats for real now > > > > > > Jens, this regression is still in .35-rc1 and triggers in about 25% of all > > > -tip boot tests. > > > > > > The above commit is using sched_clock() in an unsafe way - please fix it or > > > revert it. > > > > > > The local_clock() changes PeterZ is working on are still WIP, it's not sure > > > we'll have it before .36. > > > > OK, I guess we'll have to solve this differently for .35 - I'll cook up > > something simple, if need be revert the change. > > I suspect you can put get_cpu/put_cpu around it and use cpu_clock(). The > cross-CPU effects will still be there and there might be weird stats.
It'll shut it up at least, which is the primary concern at this point.
-- Jens Axboe
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