On Fri, Nov 04, 2011 at 09:30:52AM -0400, Mike Snitzer wrote: > > FWIW, yet another use-after-free crash, this time however in multipath_end_io: > > > > [96875.870593] Unable to handle kernel pointer dereference at virtual kernel address 6b6b6b6b6b6b6000 > > [96875.870602] Oops: 0038 [#1] > > [96875.870674] PREEMPT SMP DEBUG_PAGEALLOC > > [96875.870683] Modules linked in: dm_round_robin sunrpc ipv6 qeth_l2 binfmt_misc dm_multipath scsi_dh dm_mod qeth ccwgroup [la\ > > st unloaded: scsi_wait_scan] > > [96875.870722] CPU: 2 Tainted: G W 3.0.7-50.x.20111024-s390xdefault #1 > > [96875.870728] Process udevd (pid: 36697, task: 0000000072c8a3a8, ksp: 0000000057c43868) > > [96875.870732] Krnl PSW : 0704200180000000 000003e001347138 (multipath_end_io+0x50/0x140 [dm_multipath]) > > [96875.870746] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:2 PM:0 EA:3 > > [96875.870751] Krnl GPRS: 0000000000000000 000003e000000000 6b6b6b6b6b6b6b6b 00000000717ab940 > > [96875.870755] 0000000000000000 00000000717abab0 0000000000000002 0700000000000008 > > [96875.870759] 0000000000000002 0000000000000000 0000000058dd37a8 000000006f845478 > > [96875.870764] 000003e0012e1000 000000005613d1f0 000000007a737bf0 000000007a737ba0 > > [96875.870768] Krnl Code: 000003e00134712a: b90200dd ltgr %r13,%r13 > > [96875.870793] 000003e00134712e: a7840017 brc 8,3e00134715c > > [96875.870800] 000003e001347132: e320d0100004 lg %r2,16(%r13) > > [96875.870809] >000003e001347138: e31020180004 lg %r1,24(%r2) > > [96875.870818] 000003e00134713e: e31010580004 lg %r1,88(%r1) > > [96875.870827] 000003e001347144: b9020011 ltgr %r1,%r1 > > [96875.870835] 000003e001347148: a784000a brc 8,3e00134715c > > [96875.870841] 000003e00134714c: 41202018 la %r2,24(%r2) > > [96875.870889] Call Trace: > > [96875.870892] ([<0700000000000008>] 0x700000000000008) > > [96875.870897] [<000003e0012e3662>] dm_softirq_done+0x9a/0x140 [dm_mod] > > [96875.870915] [<000000000040d29c>] blk_done_softirq+0xd4/0xf0 > > [96875.870925] [<00000000001587c2>] __do_softirq+0xda/0x398 > > [96875.870932] [<000000000010f47e>] do_softirq+0xe2/0xe8 > > [96875.870940] [<0000000000158e2c>] irq_exit+0xc8/0xcc > > [96875.870945] [<00000000004ceb48>] do_IRQ+0x910/0x1bfc > > [96875.870953] [<000000000061a164>] io_return+0x0/0x16 > > [96875.870961] [<000000000019c84e>] lock_acquire+0xd2/0x204 > > [96875.870969] ([<000000000019c836>] lock_acquire+0xba/0x204) > > [96875.870974] [<0000000000615f8e>] mutex_lock_killable_nested+0x92/0x520 > > [96875.870983] [<0000000000292796>] vfs_readdir+0x8a/0xe4 > > [96875.870992] [<00000000002928e0>] SyS_getdents+0x60/0xe8 > > [96875.870999] [<0000000000619af2>] sysc_noemu+0x16/0x1c > > [96875.871024] [<000003fffd1ec83e>] 0x3fffd1ec83e > > [96875.871028] INFO: lockdep is turned off. > > [96875.871031] Last Breaking-Event-Address: > > [96875.871037] [<000003e0012e3660>] dm_softirq_done+0x98/0x140 [dm_mod] [...] > OK, thanks for the backstory. > > That is the same type of testing we've been doing with some partners > for RHEL6.2 with the qla2xxx driver. They have seen the same crash that > you originally reported here: https://lkml.org/lkml/2011/10/31/64 > > The really interesting observation that was made is that the qla2xxx > driver was made lockless in RHEL6.2. We've found that reverting the > qla2xxx lockless changes eliminates the problems seen with it and I/O > stress testing with multipath path failures. > > The zfcp driver was also made lockless upstream, via this commit: > e55f875 [SCSI] zfcp: Issue FCP command without holding SCSI host_lock > > It would be great if you could try reverting e55f875 and see how your > testing goes. Ok, we did that, and of course it sometimes runs into deadlocks (since the commit fixed a deadlock), however we still see the same crash in multipath_end_io() from above. > If doing so resolves the crashes for you then the post mortem on why > these lockless SCSI driver changes are causing such odd multipath > completion failures is going to be "fun" ;) Must be something different then... -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
