Re: [PATCH] block: Employ u64_stats_init()

[Ingo Molnar]

* Jens Axboe <axboe@xxxxxxxxx> wrote:

> On 11/12/2013 08:42 PM, John Stultz wrote:
> > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > 
> > Now that seqcounts are lockdep enabled objects, we need to properly
> > initialize them.
> > 
> > Without this patch, Fengguang was seeing:
> > [    4.127282] INFO: trying to register non-static key.
> > [    4.128027] the code is fine but needs lockdep annotation.
> > [    4.128027] turning off the locking correctness validator.
> > [    4.128027] CPU: 0 PID: 96 Comm: kworker/u4:1 Not tainted 3.12.0-next-20131108-10601-gbad570d #2
> > [    4.128027] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > [    4.128027] Workqueue: events_unbound async_run_entry_fn
> > [    4.128027]  7908e744 00000000 78019968 79dc7cf2 7a80e0a8 780199a0 7908953e 7a1b7f4d
> > [    4.128027]  7a1b7fa7 7a1b7f7d 7f368608 00000000 00000011 44374011 0000a805 7f368110
> > [    4.128027]  7f368110 85bf2a70 00000000 780199cc 7908a1c5 00000000 00000001 00000000
> > [    4.128027] Call Trace:
> > [    4.128027]  [<7908e744>] ? console_unlock+0x353/0x380
> > [    4.128027]  [<79dc7cf2>] dump_stack+0x48/0x60
> > [    4.128027]  [<7908953e>] __lock_acquire.isra.26+0x7e3/0xceb
> > [    4.128027]  [<7908a1c5>] lock_acquire+0x71/0x9a
> > [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
> > [    4.128027]  [<7940658b>] throtl_update_dispatch_stats+0x7c/0x153
> > [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
> > [    4.128027]  [<794079aa>] blk_throtl_bio+0x1c3/0x485
> > ...
> > 
> > Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> > Cc: Jens Axboe <axboe@xxxxxxxxx>
> > Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
> > Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > [jstultz: Folded in another fix from the mailing list as well as a fix
> > to that fix. Tweaked commit message.]
> > Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
> 
> Thanks for fixing this up, John/Peter. I'll get it queued up.

Note that I've already applied it to the locking tree earlier today and
sent it to Linus, didn't want to expose upstream to known false positives.

Thanks,

	Ingo
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