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Message-ID: <3877989d0806100123j1734a82fgd6d6eee6146b8423@mail.gmail.com>
Date: Tue, 10 Jun 2008 16:23:28 +0800
From: "Luming Yu" <luming.yu@gmail.com>
To: "Luck, Tony" <tony.luck@intel.com>
Subject: Re: [RFC PATCH] set TASK_TRACED before arch_ptrace code to fix a race
Cc: "Roland McGrath" <roland@redhat.com>, "Petr Tesarik" <ptesarik@suse.cz>,
       LKML <linux-kernel@vger.kernel.org>, linux-ia64@vger.kernel.org
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On Wed, Jun 4, 2008 at 5:31 AM, Luck, Tony <tony.luck@intel.com> wrote:
>> What do you mean by "extra"?  There is a SIGTRAP sent after execve
>> completes when ptraced, even when PTRACE_SYSCALL is not being used.
>> So for an execve that succeeds under PTRACE_SYSCALL, there is a
>> ptrace_notify at syscall entry, then a SIGTRAP queued (i.e., not seen
>> by ptrace if blocked), then a ptrace_notify at syscall exit.  If
>> that's what's happening (including the blocked SIGTRAP not being seen
>> by the ptracer, i.e. strace), then there is no mystery (and no bug).
>
> This might not be the same bug ... but I do have a definite 100%
> reproducible bug (latest git kernel, old version of strace (4.5.15-1.el4.1))
>
> Run:
>
>        $ strace -o logit -f make

For this test case, utrace doesn't work too..