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Date:   Thu, 15 Dec 2022 15:19:51 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Damien Le Moal <damien.lemoal@opensource.wdc.com>
Cc:     Wei Chen <harperchen1110@gmail.com>, linux-ide@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        syzbot <syzkaller@googlegroups.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Chuck Lever <chuck.lever@oracle.com>,
        Jeff Layton <jlayton@kernel.org>
Subject: Re: possible deadlock in __ata_sff_interrupt
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On Thu, Dec 15, 2022 at 06:48:20PM +0900, Damien Le Moal wrote:

> The problem is here: sg_rq_end_io() calling kill_fasync(). But at a quick
> glance, this is not the only driver calling kill_fasync() with a spinlock
> held with irq disabled... So there may be a fundamental problem with
> kill_fasync() function if drivers are allowed to do that, or the reverse,
> all drivers calling that function with a lock held with irq disabled need
> to be fixed.
> 
> Al, Chuck, Jeff,
> 
> Any thought ?

What is the problem with read_lock_irqsave() called with irqs disabled?
read_lock_irq() would have been a bug in such conditions, of course, but
that's not what we use...