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Re: [PATCH] malloc: Run fork handler as late as possible [BZ #19431]

From: Florian Weimer <fweimer at redhat dot com>
To: Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>
Cc: GNU C Library <libc-alpha at sourceware dot org>
Date: Tue, 10 May 2016 21:51:42 +0200
Subject: Re: [PATCH] malloc: Run fork handler as late as possible [BZ #19431]
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On 05/10/2016 08:05 PM, Tulio Magno Quites Machado Filho wrote:

Florian Weimer <fweimer@redhat.com> writes:

On 05/10/2016 03:41 PM, Tulio Magno Quites Machado Filho wrote:

The child is getting into a deadlock if the signal arrives before the parent
is able to complete __malloc_fork_unlock_parent().


But this could have happened before as well, right?


Maybe, but I'm not able to reproduce this error before the removal of malloc
hooks from the fork handler.

Hmm, maybe we are talking about a different failure? I get a raredeadlock with an older glibc:

[fweimer@oldenburg tmp]$ x=0; while ./tst-mallocfork ; do x=$((x + 1)); done; echo $? $x

Timed out: killed the child process
0 22156

[fweimer@oldenburg tmp]$ x=0; while ./tst-mallocfork ; do x=$((x + 1)); done; echo $? $x

Timed out: killed the child process
0 10940

We looked at the test case internally a while back, and concluded it wasinvalid for several reasons.


Thanks,
Florian

Follow-Ups:
- [PATCH] malloc: Re-add protection for recursive calls to __malloc_fork_lock_parent
  - From: Tulio Magno Quites Machado Filho

References:
- Re: [PATCH] malloc: Run fork handler as late as possible [BZ #19431]
  - From: Tulio Magno Quites Machado Filho
- Re: [PATCH] malloc: Run fork handler as late as possible [BZ #19431]
  - From: Florian Weimer
- Re: [PATCH] malloc: Run fork handler as late as possible [BZ #19431]
  - From: Tulio Magno Quites Machado Filho

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