From: Tom Horsley <tom.horsley@att.net>
To: linux-kernel@vger.kernel.org
Subject: ptrace & /proc deadlock due to mm_for_maps cred_guard_mutex patch
Date: Wed, 2 Sep 2009 19:28:09 -0400 [thread overview]
Message-ID: <20090902192809.5f3efb48@zooty> (raw)
The redhat bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=520206#c2
describes a test program that demonstrates an apparent
deadlock ptrace can get into as a result of the
patch:
commit 704b836cbf19e885f8366bccb2e4b0474346c02d
Author: Oleg Nesterov <oleg@redhat.com>
Date: Fri Jul 10 03:27:40 2009 +0200
mm_for_maps: take ->cred_guard_mutex to fix the race with exec
ptrace hangs attempting to read the newly exec'ed debugged
child process /proc/pid/maps file, and the child is obviously
never going to advance as long as it is stopped by ptrace.
I haven't seen any activity on the bugzilla, so since this
was a kernel.org patch I figured I'd mention it over here.
As the bugzilla says, it is possible to work around this by
single stepping the debugged process before reading the maps
file.
reply other threads:[~2009-09-02 23:28 UTC|newest]
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