On Wed, 28 Dec 2011, Tejun Heo wrote: > On Wed, Dec 28, 2011 at 12:33:01AM -0800, Hugh Dickins wrote: > > > However, there are a couple of other unhealthy symptoms I've noticed > > under load in -next's block/cfq layer, both with and without your patch. > > > > One is kernel BUG at block/cfq-iosched.c:2585! > > BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); > > > > cfq_dispatch_request+0x1a > > cfq_dispatch_requests+0x5c > > blk_peek_request+0x195 > > scsi_request_fn+0x6a > > __blk_run_queue+0x16 > > scsi_run_queue+0x18a > > scsi_next_command+0x36 > > scsi_io_completion+0x426 > > scsi_finish_command+0xaf > > scsi_softirq_done+0xdd > > blk_done_softirq+0x6c > > __do_softirq+0x80 > > call_softirq+0x1c > > do_softirq+0x33 > > irq_exit+0x3f > > do_IRQ+0x97 > > ret_from_intr > > > > I've had that one four times now on different machines; but quicker > > to reproduce are these warnings from CONFIG_DEBUG_LIST=y: > > > > ------------[ cut here ]------------ > > WARNING: at lib/list_debug.c:53 __list_del_entry+0x8d/0x98() > > Hardware name: 4174AY9 > > list_del corruption. prev->next should be ffff880005aa1380, but was 6b6b6b6b6b6b6b6b > > Modules linked in: snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device > > Pid: 29241, comm: cc1 Tainted: G W 3.2.0-rc6-next-20111222 #18 > > Call Trace: > > <IRQ> [<ffffffff810544b4>] warn_slowpath_common+0x80/0x98 > > [<ffffffff81054560>] warn_slowpath_fmt+0x41/0x43 > > [<ffffffff811fc1a1>] __list_del_entry+0x8d/0x98 > > [<ffffffff811df8ab>] cfq_remove_request+0x3b/0xdf > > [<ffffffff811df989>] cfq_dispatch_insert+0x3a/0x87 > > [<ffffffff811dfb3b>] cfq_dispatch_request+0x65/0x92 > > [<ffffffff811dfbc4>] cfq_dispatch_requests+0x5c/0x133 > > [<ffffffff812e103e>] ? scsi_request_fn+0x3b6/0x3d3 > > [<ffffffff811d3069>] blk_peek_request+0x195/0x1a6 > > [<ffffffff812e103e>] ? scsi_request_fn+0x3b6/0x3d3 > > [<ffffffff812e0cf5>] scsi_request_fn+0x6d/0x3d3 > > [<ffffffff811d0730>] __blk_run_queue+0x19/0x1b > > [<ffffffff811d0bfd>] blk_run_queue+0x21/0x35 > > [<ffffffff812e08c4>] scsi_run_queue+0x11f/0x1b9 > > [<ffffffff812e205c>] scsi_next_command+0x36/0x46 > > [<ffffffff812e24dc>] scsi_io_completion+0x426/0x4a9 > > [<ffffffff812dc0b2>] scsi_finish_command+0xaf/0xb8 > > [<ffffffff812e200c>] scsi_softirq_done+0xdd/0xe5 > > [<ffffffff811d79c6>] blk_done_softirq+0x76/0x8a > > [<ffffffff8105a28d>] __do_softirq+0x98/0x136 > > [<ffffffff814e649c>] call_softirq+0x1c/0x30 > > [<ffffffff8102f187>] do_softirq+0x38/0x81 > > [<ffffffff8105a596>] irq_exit+0x4e/0xb6 > > [<ffffffff8102ee9e>] do_IRQ+0x97/0xae > > [<ffffffff814e49f0>] common_interrupt+0x70/0x70 > > <EOI> [<ffffffff814e4a8e>] ? retint_swapgs+0xe/0x13 > > ---[ end trace 61fdaa1b260613d1 ]--- > > Hmm... that looks like cfqq being freed before unlinked. I'll try to > reproduce it. Is there any particular workload you were running? "It's the tmpfs swapping test that I've been running, with variations, for years. System booted with mem=700M and 1.5G swap, two repetitious make -j20 kernel builds (of a 2.6.24 kernel: I stuck with that because the balance of built to unbuilt source grows smaller with later kernels), one directly in a tmpfs, the other in a 1k-block ext2 (that I drive with ext4's CONFIG_EXT4_USE_FOR_EXT23) on /dev/loop0 on a 450MB tmpfs file." I doubt much of that (quoted from an older mail to someone else about one of the many other bugs it's found) is relevant: maybe just plenty of file I/O and swapping. Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
