From: Andrew Morton <akpm@linux-foundation.org>
To: Tejun Heo <tj@kernel.org>
Cc: Balbir Singh <bsingharora@gmail.com>,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH] delayacct: Fix crash in delayacct_blkio_end() after delayacct init failure
Date: Tue, 24 Jul 2018 12:29:13 -0700 [thread overview]
Message-ID: <20180724122913.af508cf58033e9b1147e7def@linux-foundation.org> (raw)
In-Reply-To: <20180724175542.GP1934745@devbig577.frc2.facebook.com>
On Tue, 24 Jul 2018 10:55:42 -0700 Tejun Heo <tj@kernel.org> wrote:
> While forking, if delayacct init fails due to memory shortage, it
> continues expecting all delayacct users to check task->delays pointer
> against NULL before dereferencing it, which all of them used to do.
>
> c96f5471ce7d ("delayacct: Account blkio completion on the correct
> task"), while updating delayacct_blkio_end() to take the target task
> instead of always using %current, made the function test NULL on
> %current->delays and then continue to operated on @p->delays. If
> %current succeeded init while @p didn't, it leads to the following
> crash.
>
lgtm.
How did you make this happen, btw? Fault injection, or did a small
GFP_KERNEL allocation fail?
next prev parent reply other threads:[~2018-07-24 19:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-24 17:55 Tejun Heo
2018-07-24 19:29 ` Andrew Morton [this message]
2018-07-24 19:30 ` Tejun Heo
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