linux-kernel - Re: [PATCH] core dump: remain dumpable

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Message-ID: <20071011104942.GA144@tv-sign.ru>
Date:	Thu, 11 Oct 2007 14:49:42 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Roland McGrath <roland@...hat.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] core dump: remain dumpable

On 10/11, Roland McGrath wrote:
>
> > Hmm. Actually, do we need any check? If another thread (or CLONE_VM task)
> > already started do_coredump(), we must see SIGNAL_GROUP_EXIT when we take
> > ->mmap_sem. In that case coredump_wait() does nothing but returns -EAGAIN.
> 
> You're right again here.  I'm sure the old use predates this checking in
> zap_threads, so it's understandable that something different was needed for
> this synchronization before.

Ugh, sorry, I was wrong. coredump_wait() initializes mm->core_done and sets
mm->core_startup_done before checking SIGNAL_GROUP_EXIT. This means we have
to check ->core_waiters or SIGNAL_GROUP_EXIT before calling coredump_wait().

Oleg.

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