From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from infao0809.mpi-klsb.mpg.de ([139.19.1.49]:53258 "EHLO hera.mpi-klsb.mpg.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758428Ab3KMS7z (ORCPT ); Wed, 13 Nov 2013 13:59:55 -0500 Message-ID: <5283CC25.3060007@mpi-sws.org> Date: Wed, 13 Nov 2013 19:59:49 +0100 From: Pedro Fonseca MIME-Version: 1.0 To: linux-btrfs@vger.kernel.org Subject: Re: Sync() causes null pointer dereference and warning message in run_clustered_refs() References: <527E714A.3040206@mpi-sws.org> In-Reply-To: <527E714A.3040206@mpi-sws.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, Does anyone have an idea about what could be causing this null pointer bug? Pedro On 11/09/2013 06:30 PM, Pedro Fonseca wrote: > Hi, > > I've encountered a bug that triggers a warning message ("list_del > corruption. next->prev should be d9d0ae28, but was d9d5d5e8") and > subsequently causes a null pointer dereference while running a custom > test case on btrfs (kernel 3.11.1), inside a QEMU based VM. > > The bug was triggered during the execution of two concurrent sync() > calls. > > Here's the list of FS operations executed immediately before the crash: >> CPU: 0 Op: fdatasync >> CPU: 0 Op: btrfs_ioctl_device_delete >> CPU: 0 Op: rename (file: "d16/da6/l131" renamed to "d16/d21/d38/l13b") >> CPU: 0 Op: btrfs_subvol_snapshot >> CPU: 1 Op: fdatasync >> CPU: 1 Op: btrfs_ioctl_device_delete >> CPU: 1 Op: rename (file: "d16/da6/l131" renamed to >> "d16/d21/d38/l13b") >> CPU: 1 Op: btrfs_subvol_snapshot >> CPU: 0 Op: dwrite (file: "d16/d21/f51") >> CPU: 0 Op: chown (file: "d16/da6/f114") >> CPU: 0 Op: write (file: "d16/d21/f107") >> CPU: 0 Op: sync >> CPU: 1 Op: dwrite (file: "d16/d21/f51") >> CPU: 1 Op: chown (file: "d16/c1c") >> CPU: 1 Op: write (file: "d16/d21/f107") >> CPU: 1 Op: sync > (Note that the entries in this log refer to the moment when the > operations were initiated, i.e., operations on different CPUs may > overlap): > > > And here's the system log output: >> [ 127.830656] ------------[ cut here ]------------ >> [ 127.830656] WARNING: CPU: 0 PID: 2791 at >> /local/pfonseca/piking/kernel-build/linux-3.11.1-fs-static/lib/list_debug.c:62 >> __list_del_entry+0x62/0x71() >> [ 127.830656] list_del corruption. next->prev should be d9d0ae28, >> but was d9d5d5e8 >> [ 127.830656] Modules linked in: loop rtc_cmos pcspkr tpm_tis >> freq_table mperf i2c_piix4 >> [ 127.830656] CPU: 0 PID: 2791 Comm: fsstress Not tainted 3.11.1 #2 >> [ 127.830656] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 >> [ 127.830656] 0000003e c4027dd8 c176917a c1a13c6e c4027df0 c102d1c0 >> c138838f d9d0ae28 >> [ 127.830656] d9d0ae28 d9d0ade0 c4027e08 c102d23b 00000009 c4027e00 >> c1a13dad c4027e1c >> [ 127.830656] c4027e28 c138838f c1a13c6e 0000003e c1a13dad d9d0ae28 >> d9d5d5e8 d9d0ade0 >> [ 127.830656] Call Trace: >> [ 127.830656] [] dump_stack+0x41/0x57 >> [ 127.830656] [] warn_slowpath_common+0x5e/0x75 >> [ 127.830656] [] ? __list_del_entry+0x62/0x71 >> [ 127.830656] [] warn_slowpath_fmt+0x26/0x2a >> [ 127.830656] [] __list_del_entry+0x62/0x71 >> [ 127.830656] [] run_clustered_refs+0x877/0x8b0 >> [ 127.830656] [] ? btrfs_find_ref_cluster+0xc9/0x10e >> [ 127.830656] [] btrfs_run_delayed_refs+0x1f2/0x35b >> [ 127.830656] [] ? __delayacct_blkio_end+0x30/0x36 >> [ 127.830656] [] btrfs_commit_transaction+0x60/0x986 >> [ 127.830656] [] ? start_transaction+0x320/0x3cd >> [ 127.830656] [] ? >> btrfs_attach_transaction_barrier+0x17/0x3c >> [ 127.830656] [] btrfs_sync_fs+0x4c/0x53 >> [ 127.830656] [] sync_fs_one_sb+0x17/0x19 >> [ 127.830656] [] iterate_supers+0x54/0x95 >> [ 127.830656] [] ? SyS_splice+0x455/0x455 >> [ 127.830656] [] sys_sync+0x46/0x70 >> [ 127.830656] [] sysenter_do_call+0x12/0x26 >> [ 127.830656] ---[ end trace 626899e11111abbe ]--- >> [ 127.830656] BUG: unable to handle kernel NULL pointer dereference >> at (null) >> [ 127.830656] IP: [] rb_erase+0x177/0x236 >> [ 127.830656] *pde = 00000000 >> [ 127.830656] Oops: 0000 [#1] SMP >> [ 127.830656] Modules linked in: loop rtc_cmos pcspkr tpm_tis >> freq_table mperf i2c_piix4 >> [ 127.830656] CPU: 0 PID: 2791 Comm: fsstress Tainted: G W 3.11.1 #2 >> [ 127.830656] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 >> [ 127.830656] task: de60efc0 ti: c4026000 task.ti: c4026000 >> [ 127.830656] EIP: 0060:[] EFLAGS: 00000246 CPU: 0 >> [ 127.830656] EIP is at rb_erase+0x177/0x236 >> [ 127.830656] EAX: 00000000 EBX: 00000000 ECX: d9d0d180 EDX: d9cebddc >> [ 127.830656] ESI: 00000001 EDI: d9d0ade0 EBP: c4027e28 ESP: c4027e18 >> [ 127.830656] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 >> [ 127.830656] CR0: 8005003b CR2: 00000000 CR3: 059d8000 CR4: 00000690 >> [ 127.830656] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 >> [ 127.830656] DR6: 00000000 DR7: 00000000 >> [ 127.830656] Stack: >> [ 127.830656] d9d0ade0 d9d0ade0 00000000 d9d0ade0 c4027eb8 c12a7fe0 >> 00000000 00000001 >> [ 127.830656] 00000000 00000002 00000000 c4027f0c 00cc9a28 d9cebddc >> de4d1000 0000095c >> [ 127.830656] de4d1000 00000007 00000000 0000001e d9cebd60 00000000 >> 00000000 d9cebde0 >> [ 127.830656] Call Trace: >> [ 127.830656] [] run_clustered_refs+0x2f3/0x8b0 >> [ 127.830656] [] ? btrfs_find_ref_cluster+0xc9/0x10e >> [ 127.830656] [] btrfs_run_delayed_refs+0x1f2/0x35b >> [ 127.830656] [] ? __delayacct_blkio_end+0x30/0x36 >> [ 127.830656] [] btrfs_commit_transaction+0x60/0x986 >> [ 127.830656] [] ? start_transaction+0x320/0x3cd >> [ 127.830656] [] ? >> btrfs_attach_transaction_barrier+0x17/0x3c >> [ 127.830656] [] btrfs_sync_fs+0x4c/0x53 >> [ 127.830656] [] sync_fs_one_sb+0x17/0x19 >> [ 127.830656] [] iterate_supers+0x54/0x95 >> [ 127.830656] [] ? SyS_splice+0x455/0x455 >> [ 127.830656] [] sys_sync+0x46/0x70 >> [ 127.830656] [] sysenter_do_call+0x12/0x26 >> [ 127.830656] Code: 73 04 85 f6 89 70 08 89 43 04 89 59 04 74 07 89 >> c7 83 cf 01 89 3e 89 c6 89 d8 8b 58 08 89 59 04 89 48 08 e9 8c 00 00 >> 00 8b 41 08 00 01 75 2e 8b 58 04 89 ce 83 ce 01 89 59 08 89 48 >> 04 89 33 >> [ 127.830656] EIP: [] rb_erase+0x177/0x236 SS:ESP >> 0068:c4027e18 >> [ 127.830656] CR2: 0000000000000000 >> [ 127.830656] ---[ end trace 626899e11111abbf ]--- > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html