Re: [PATCH] kernel/delayacct.c: check NULL for member variable'delays' in all extern functions.

From: Andrew Morton
Date: Wed Aug 21 2013 - 18:10:30 EST


On Tue, 20 Aug 2013 10:40:03 +0800 Chen Gang <gang.chen@xxxxxxxxxxx> wrote:

> The member variable 'delays' may be NULL, so need check NULL before use
> it for all extern functions, just like __delayacct_tsk_init() and
> __delayacct_add_tsk() have already done.

If task.delays is NULL, the kernel will oops. I don't recall seeing
such oops reports hence I suspect that you missed some check somewhere.

For example, delayacct_blkio_start() checks current->delays before
calling __delayacct_blkio_start(), so why retest current->delays in
__delayacct_blkio_start()?
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