From: Oleg Nesterov <oleg@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Ed Swierk <eswierk@aristanetworks.com>,
rml@tech9.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal()
Date: Tue, 27 Jan 2009 01:41:24 +0100 [thread overview]
Message-ID: <20090127004124.GA10632@redhat.com> (raw)
In-Reply-To: <20090126233732.GA23128@elte.hu>
On 01/27, Ingo Molnar wrote:
>
> * Ed Swierk <eswierk@aristanetworks.com> wrote:
>
> > Take 2:
> >
> > With print-fatal-signals=1 on a kernel with CONFIG_PREEMPT=y, sending an
> > unexpected signal to a process causes a BUG: using smp_processor_id() in
> > preemptible code.
> >
> > get_signal_to_deliver() releases the siglock before calling
> > print_fatal_signal(), which calls show_regs(), which calls
> > smp_processor_id(), which is not supposed to be called from a
> > preemptible thread.
> >
> > Signed-off-by: Ed Swierk <eswierk@aristanetworks.com>
>
> applied to tip/core/urgent, thanks Ed!
Ed, Ingo, but isn't it better to just use raw_smp_processor_id() in
__show_regs() ? This is only debug info, the printed CPU doesn't
have the "exact" meaning.
And, without the comment, it is not easy to see why print_fatal_signal()
disables preeemption before show_regs().
Oleg.
next prev parent reply other threads:[~2009-01-27 0:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-26 23:00 [PATCH] Fix BUG: using smp_processor_id() in preemptible code in print_fatal_signal() Ed Swierk
2009-01-26 23:15 ` Ingo Molnar
2009-01-26 23:33 ` Ed Swierk
2009-01-26 23:37 ` Ingo Molnar
2009-01-27 0:41 ` Oleg Nesterov [this message]
2009-01-27 1:34 ` Ed Swierk
2009-01-27 3:02 ` Oleg Nesterov
2009-01-27 12:46 ` Ingo Molnar
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