From: Peter Zijlstra <peterz@infradead.org>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>,
stable@kernel.org,
Michael Chapman <redhat-bugzilla@very.puzzling.org>,
Ciriaco Garcia de Celis <sysman@etherpilot.com>
Subject: Re: [PATCH v2] sched: fix user time incorrectly accounted as system time on 32 bit
Date: Tue, 14 Sep 2010 16:37:28 +0200 [thread overview]
Message-ID: <1284475048.2275.517.camel@laptop> (raw)
In-Reply-To: <20100914143513.GB8415@redhat.com>
On Tue, 2010-09-14 at 16:35 +0200, Stanislaw Gruszka wrote:
> We have 32 bit variable overflow possibility when multiply in
> task_times() and thread_group_times() functions. If overflow happens
> calculated scaled utime value become wrongly small and scaled stime
> wrongly big.
Ah, right, (u64)foo * bar would have worked too I guess, but yeah, the
used (u64)(foo * bar) is wrong.
> Reported here:
> https://bugzilla.redhat.com/show_bug.cgi?id=633037
> https://bugzilla.kernel.org/show_bug.cgi?id=16559
>
> Reported-by: Michael Chapman <redhat-bugzilla@very.puzzling.org>
> Reported-by: Ciriaco Garcia de Celis <sysman@etherpilot.com>
> Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: <stable@kernel.org> # 2.6.32.19+ (partially) and 2.6.33+
> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Thanks, got it.
next prev parent reply other threads:[~2010-09-14 14:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 14:35 [PATCH v2] sched: fix user time incorrectly accounted as system time on 32 bit Stanislaw Gruszka
2010-09-14 14:37 ` Peter Zijlstra [this message]
2010-09-15 10:01 ` [tip:sched/urgent] sched: Fix user time incorrectly accounted as system time on 32-bit tip-bot for Stanislaw Gruszka
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