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Date: Fri, 7 Nov 2008 10:03:04 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Ken Chen <kenchen@google.com>,
       linux-kernel@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [patch] add /proc/pid/stack to dump task's stack trace
Message-ID: <20081107090304.GA30540@elte.hu>
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btw., the feature works beautifully:

task sleeping/blocked:

 # cat /proc/1/stack
 [<ffffffff802bfe75>] do_select+0x51a/0x582
 [<ffffffff802c0059>] core_sys_select+0x17c/0x218
 [<ffffffff802c0344>] sys_select+0x99/0xc1
 [<ffffffff8020c23b>] system_call_fastpath+0x16/0x1b
 [<ffffffffffffffff>] 0xffffffffffffffff

task running on this CPU:

 # cat /proc/self/stack
 [<ffffffff80216f79>] save_stack_trace_tsk+0x26/0x44
 [<ffffffff802f59a5>] proc_pid_stack+0x6e/0xd3
 [<ffffffff802f6da3>] proc_info_read+0x68/0xba
 [<ffffffff802b2f17>] vfs_read+0xa9/0xe3
 [<ffffffff802b301f>] sys_read+0x4c/0x73
 [<ffffffff8020c23b>] system_call_fastpath+0x16/0x1b
 [<ffffffffffffffff>] 0xffffffffffffffff

task running on another CPU in user-space:

 # cat /proc/18579/stack
 [<ffffffffffffffff>] 0xffffffffffffffff

task running on another CPU in kernel-space:

 # cat /proc/18579/stack
 [<ffffffff8026f111>] audit_syscall_exit+0x9c/0xed
 [<ffffffff80214b49>] syscall_trace_leave+0x94/0xbb
 [<ffffffffffffffff>] 0xffffffffffffffff

	Ingo
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