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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, drepper@redhat.com,
	jens@mcbone.net, mingo@elte.hu, peterz@infradead.org,
	sonnyrao@us.ibm.com, stable@kernel.org, tglx@linutronix.de
Subject: Re: [PATCH v2] execve: must clear current->clear_child_tid
Date: Sat, 01 Aug 2009 09:52:46 +0200	[thread overview]
Message-ID: <4A73F44E.1010508@gmail.com> (raw)
In-Reply-To: <20090801064438.GA30800@redhat.com>

Oleg Nesterov a écrit :
> On 08/01, Eric Dumazet wrote:
>> I only wonder about core dumping, since mm_release() is also used by exiting tasks.
>>
>> Isnt clear_child_tid used by gdb or other debugger ?
> 
> Afaics it is not...
> 
> At least, I can't see how gdb (or any other user-space app) can figure
> out the value of ->clear_child_tid.
> 

Yep, this was from old Unixes time, when core file included the 'u' structure ...

Dont worry ;)


> 
> 
> Not that this really matters, but please note also that it is possible
> that the coredumping task has ->clear_child_tid == NULL anyway, even
> without this change. The PF_SIGNALED check in mm_release() is not 100&
> reliable.
> 
> Suppose a thread T sleeps in do_exit()->ptrace_event(PT_TRACE_EXIT) path.
> Another thread starts a coredump and kills T via zap_process(). This wakes
> up T, it calls exit_mm()->mm_release() without PF_SIGNALED.
> 
> Oleg.
> 


      reply	other threads:[~2009-08-01  7:54 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-31 21:42 + execve-must-clear-current-clear_child_tid.patch added to -mm tree akpm
2009-07-31 22:29 ` Oleg Nesterov
2009-08-01  0:38   ` Linus Torvalds
2009-08-01  0:51     ` Andrew Morton
2009-08-01  1:54       ` [PATCH v2] execve: must clear current->clear_child_tid Oleg Nesterov
2009-08-01  6:12         ` Eric Dumazet
2009-08-01  6:44           ` Oleg Nesterov
2009-08-01  7:52             ` Eric Dumazet [this message]

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