From: Jay Lan <jlan@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [BUG] running strace utility can cause system to hang at sys_ptrace
Date: Thu, 13 Jul 2006 18:24:40 +0000 [thread overview]
Message-ID: <44B68FE8.3050101@sgi.com> (raw)
In-Reply-To: <44B689B9.3090902@sgi.com>
Correct David's email addr. Add Christoph Hellwig.
Regards,
- jay
Jay Lan wrote:
> We ran into a system hang problem at sys_ptrace.
>
> The system may hang if a user attempts to "strace" a pthreaded
> application that is making frequent calls to pthread_create &
> pthread_exit.
> The hang is caused by a task sleeping (yield()) while holding the
> tasklist_lock.
>
> Note that the problem appears to exist ONLY on IA64. IA64 has an
> ARCH-specific implementation of sys_ptrace().
>
> The failing path is:
>
> sys_ptrace
> read_lock(&tasklist_lock);
> find_thread_for_addr(child, addr);
> thread_matches(p, addr)
> ptrace_check_attach(thread, 0)
> wait_task_inactive(child);
> yield();
>
> Failures always show 1 task sleeping with the backtrace listed
> above, plus tasks on all cpus spinning waiting to write_lock the
> tasklist lock.
>
> Sleeping
> Stack traceback for pid 31069
> 0xe00000343b800000 31069 0 3 R 0xe00000343b8003a0 strace
> 0xa000000100981c60 schedule+0x2460
> 0xa00000010007d4d0 sys_sched_yield+0x110
> 0xa000000100982120 yield+0x40
> 0xa000000100082f10 wait_task_inactive+0x170
> 0xa0000001000a2570 ptrace_check_attach+0x1d0
> 0xa00000010002e9b0 sys_ptrace+0x1f0
> 0xa00000010000c900 ia64_ret_from_syscall
>
> CPU 0
> 0xe00000343b5f0000 4973 0 3 C 0xe00000343b5f03a0 thdcrex
> 0xa00000010000caa0 ia64_leave_kernel
> 0xa00000010053d0a0 _raw_write_lock+0x120
> 0xa0000001009854d0 _write_lock_irq+0x30
> 0xa000000100093a00 do_exit+0xae0
> 0xa000000100094560 sys_exit+0x20
> 0xa00000010000c900 ia64_ret_from_syscall
>
> CPU 1
> 0xe000003038880000 4972 0 1 R 0xe0000030388803a0 thdcrex
> 0xa00000010000caa0 ia64_leave_kernel
> 0xa00000010053d0a0 _raw_write_lock+0x120
> 0xa0000001009854d0 _write_lock_irq+0x30
> 0xa0000001000880e0 copy_process+0x1f80
> 0xa000000100088e30 do_fork+0x150
> 0xa00000010000c160 sys_clone2+0x60
> 0xa00000010000c900 ia64_ret_from_syscall
>
>
> Regards,
> - jay
> -
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next prev parent reply other threads:[~2006-07-13 18:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-13 17:58 [BUG] running strace utility can cause system to hang at sys_ptrace Jay Lan
2006-07-13 18:24 ` Jay Lan [this message]
2006-07-13 18:45 ` Christoph Hellwig
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