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From: Pavel Machek <pavel@ucw.cz>
To: Charles Gong <cggong@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] Fix sysrq emergency thaw
Date: Fri, 5 Aug 2016 22:14:47 +0200	[thread overview]
Message-ID: <20160805201447.GC7999@amd> (raw)
In-Reply-To: <5823da614460b8c40809e6e0a6de172a9c4f4611.1468965479.git.cggong@fb.com>

On Wed 2016-07-20 16:11:16, Charles Gong wrote:
> "SYSRQ + J" triggers a call to emergency_thaw_all(). Currently, this
> is an infinite loop. Once we trigger it, we'll need to do a hard
> power-cycle. There are users reporting this bug from 2012 to 2016, for
> example, at https://bugzilla.kernel.org/show_bug.cgi?id=47741.
> 
> This happens because thaw_bdev() fails to return -EINVAL in the
> non-frozen case, so fix it so that do_one_thaw() can recognize this case
> and quit from looping. I checked that none of the other thaw_bdev()
> callers check the return value.
> 
> The regression was introduced in commit 4504230a7156 ("freeze_bdev: grab
> active reference to frozen superblocks").
> 
> Reviewed-by: Chris Mason <clm@fb.com>
> Signed-off-by: Charles Gong <cggong@fb.com>

Acked-by: Pavel Machek <pavel@ucw.cz>

(even magic should be finite...)
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2016-08-05 20:14 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-20 23:11 [PATCH] Fix sysrq emergency thaw Charles Gong
2016-09-02 22:29 ` [RESEND PATCH] " Charles Gong
2016-08-05 20:14 ` Pavel Machek [this message]
     [not found] <5823da614460b8c40809e6e0a6de172a9c4f4611.1468015143.git.cggong@fb.com>
2016-07-19 12:15 ` [PATCH] " Chris Mason

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