From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Luming Yu" Date: Wed, 04 Jun 2008 02:16:35 +0000 Subject: Re: [RFC PATCH] set TASK_TRACED before arch_ptrace code to fix a race Message-Id: <3877989d0806031916wf11bb2t3847aa630fb39e60@mail.gmail.com> List-Id: References: <3877989d0805211947i54bacc7cv619541e9b40824fb@mail.gmail.com> <3877989d0805251830w70f19e4cu46fbc32148217749@mail.gmail.com> <3877989d0805262031i29db16bcjfa31652afc746b49@mail.gmail.com> <20080527040454.053C526FA9E@magilla.localdomain> <3877989d0805262249yab130cbyfc5f5e54065cec5c@mail.gmail.com> <20080527061209.9A24426FAA6@magilla.localdomain> <1211869515.29836.2.camel@elijah.suse.cz> <3877989d0806022304w35764b17p9d4c3c95eceae0f5@mail.gmail.com> <48450864.6080707@suse.cz> <48455619.6040608@suse.cz> In-Reply-To: <48455619.6040608@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Petr Tesarik Cc: Roland McGrath , LKML , linux-ia64@vger.kernel.org > It's definitely a bug in strace. For some reason (I don't care about) > the execve() syscall produces an extra notification. However, this > notification message is suppressed when SIGTRAP is blocked. This > explains why the test case fails only when SIGTRAP is blocked. This is exact problem I suspected and I was trying to address in my hack.. Since there are several processes involved in the pretty complex ptrace scenario., I need to capture all processes context with kdump to confirm this is exact root-cause for the problem. But kdump doesn't work for me..I'm trying to solve it now.. I'm also in doubt about the semantic correctness of the test case.. Since SIGTRAP is so necessary to get ptrace work, is it legitimate to block it in test case? One more thing I need to say is: Same strace works for utrace enabled kernel on IA64.. If the bug is in strace, how could it happen?