Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759658Ab0GQBSt (ORCPT ); Fri, 16 Jul 2010 21:18:49 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:38953 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755494Ab0GQBSs (ORCPT ); Fri, 16 Jul 2010 21:18:48 -0400 MIME-Version: 1.0 From: Kyle Moffett Date: Fri, 16 Jul 2010 21:18:26 -0400 Message-ID: Subject: apr testsuite: Spinning forever in sys_futex() [SIGSTOP does not work] To: linux-kernel@vger.kernel.org, Kumar Gala , Benjamin Herrenschmidt Cc: Kyle D Moffett Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1736 Lines: 56 Hi all, In the "apr" testsuite, the "testatomic" test seems to get 4 processes completely stuck in sys_futex. If I "kill -STOP" the process it continues to run, chewing CPU. It seems that "kill -KILL" works, though... Because of the "kill -STOP" problem, I can't attach to it with GDB to see where it's stuck, but I can dump /proc/$PID/stack repeatedly to see where it seems to be spinning in the kernel. My kernel version is 2.6.32.15 plus arch/powerpc board-support patches. In particular, I seem to have the following callchains (starting at sys_futex): do_futex futex_lock_pi __switch_to futex_lock_pi_atomic cmpxchg_futex_value_locked handle_page_fault do_page_fault fault_in_user_writeable get_user_pages __get_user_pages __cond_resched __switch_to get_futex_key __lock_page sync_page __switch_to drop_futex_key_refs iput 0x48026000 resume_kernel __switch_to resume_kernel __switch_to I noticed this particular problem while working on a Debian "PowerPCSPE" port [0], so it's entirely possible that my EGLIBC build is slightly broken, but even that should not make it completely impossible to "kill -STOP" a process. My particular boards use the "P2020" chipset (mpc85xx/e500v2 family). Any advice on how to further debug this would be much appreciated! Cheers, Kyle Moffett [0] http://wiki.debian.org/PowerPCSPEPort -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/