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Date: Mon, 26 Feb 2018 13:44:55 +0100 From: Jan Kara <jack@...e.cz> To: Mark Rutland <mark.rutland@....com> Cc: Jan Kara <jack@...e.cz>, linux-kernel@...r.kernel.org, linux-block@...r.kernel.org, virtualization@...ts.linux-foundation.org, linux-ext4@...r.kernel.org, Jens Axboe <axboe@...nel.dk>, "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.com> Subject: Re: v4.16-rc2: virtio-block + ext4 lockdep splats / sleeping from invalid context On Mon 26-02-18 11:38:19, Mark Rutland wrote: > On Mon, Feb 26, 2018 at 11:52:56AM +0100, Jan Kara wrote: > > On Fri 23-02-18 15:47:36, Mark Rutland wrote: > > > Hi all, > > > > > > While fuzzing arm64/v4.16-rc2 with syzkaller, I simultaneously hit a > > > number of splats in the block layer: > > > > > > * inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-R} usage in > > > jbd2_trans_will_send_data_barrier > > > > > > * BUG: sleeping function called from invalid context at mm/mempool.c:320 > > > > > > * WARNING: CPU: 0 PID: 0 at block/blk.h:297 generic_make_request_checks+0x670/0x750 > > > > > > ... I've included the full splats at the end of the mail. > > > > > > These all happen in the context of the virtio block IRQ handler, so I > > > wonder if this calls something that doesn't expect to be called from IRQ > > > context. Is it valid to call blk_mq_complete_request() or > > > blk_mq_end_request() from an IRQ handler? > > > > No, it's likely a bug in detection whether IO completion should be deferred > > to a workqueue or not. Does attached patch fix the problem? I don't see > > exactly this being triggered by the syzkaller but it's close enough :) > > > > Honza > > That seems to be it! > > With the below patch applied, I can't trigger the bug after ~10 minutes, > whereas prior to the patch I can trigger it in ~10 seconds. I'll leave > that running for a while just in case there's another part to the > problem, but FWIW: > > Tested-by: Mark Rutland <mark.rutland@....com> Thanks for testing! Sent the patch to Jens for inclusion. Honza -- Jan Kara <jack@...e.com> SUSE Labs, CR
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