From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx199.postini.com [74.125.245.199]) by kanga.kvack.org (Postfix) with SMTP id F248E6B0083 for ; Wed, 28 Nov 2012 09:55:18 -0500 (EST) Date: Wed, 28 Nov 2012 09:55:15 -0500 From: Dave Jones Subject: livelock in __writeback_inodes_wb ? Message-ID: <20121128145515.GA26564@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Linux Kernel We had a user report the soft lockup detector kicked after 22 seconds of no progress, with this trace.. :BUG: soft lockup - CPU#1 stuck for 22s! [flush-8:16:3137] :Pid: 3137, comm: flush-8:16 Not tainted 3.6.7-4.fc17.x86_64 #1 :RIP: 0010:[] [] __list_del_entry+0x2c/0xd0 :Call Trace: : [] redirty_tail+0x5e/0x80 : [] __writeback_inodes_wb+0x72/0xd0 : [] wb_writeback+0x23b/0x2d0 : [] wb_do_writeback+0xac/0x1f0 : [] ? __internal_add_timer+0x130/0x130 : [] bdi_writeback_thread+0x8b/0x230 : [] ? wb_do_writeback+0x1f0/0x1f0 : [] kthread+0x93/0xa0 : [] kernel_thread_helper+0x4/0x10 : [] ? kthread_freezable_should_stop+0x70/0x70 : [] ? gs_change+0x13/0x13 Looking over the code, is it possible that something could be dirtying pages faster than writeback can get them written out, keeping us in this loop indefitely ? Should there be something in this loop periodically poking the watchdog perhaps ? Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org