linux-kernel - Re: [ata_scsi_offline_dev] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:238

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Message-ID: <20171107001207.GH3252168@devbig577.frc2.facebook.com>
Date:   Mon, 6 Nov 2017 16:12:07 -0800
From:   Tejun Heo <tj@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Fengguang Wu <fengguang.wu@...el.com>,
        IDE-ML <linux-ide@...r.kernel.org>,
        Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        James Bottomley <James.Bottomley@...senpartnership.com>
Subject: Re: [ata_scsi_offline_dev] BUG: sleeping function called from
 invalid context at kernel/locking/mutex.c:238

Hello,

On Mon, Nov 06, 2017 at 03:12:31PM -0800, Linus Torvalds wrote:
> But it does seem to be a new regression in 4.14, caused by commit
> 8a97712e5314 ("scsi: make 'state' device attribute pollable"), because
> that's what added the sysfs_notify() call to scsi_device_set_state(),
> which made that spinlock be a problem.

Yeah, pinged Hannes about it a couple of weeks ago.

> That commit came in through the SCSI merge this merge window, and it
> seems to still revert cleanly.
> 
> So I do suspect that by now we should just revert that commit. It's
> not clear why that state attribute should be pollable, and the new
> code is clearly very much buggy.

I think reverting is the right thing to do right now.  If necessary,
we can make kernfs_notify() safe to be called from atomic contexts.

Thanks.

-- 
tejun