I filed a bug for null pointer dereferences I started hitting: https://bugzilla.kernel.org/show_bug.cgi?id=76451 Noticing qgroup in the trace, I tried disabling/re-enabling quota support for the filesystem. That turned out to be a mistake. Now as soon as I mount, I'm getting an oops thanks to btrfs_qgroup_rescan_worker (see below). Is there any way to disable quota support for an unmounted filesystem? I'd also appreciate any help in troubleshooting the underlying corruption here. The corruption occurred on 3.14.1, and trying 3.15.0-rc5 still gives me the same crash on mount issues. Thanks for the help. --------------- May 18 17:09:26 gonzo kernel: BTRFS info (device dm-3): disk space caching is enabled May 18 17:09:36 gonzo kernel: BUG: unable to handle kernel NULL pointer dereference at 00000004 May 18 17:09:36 gonzo kernel: IP: [<c14698c0>] ulist_next+0x10/0x40 May 18 17:09:36 gonzo kernel: *pdpt = 0000000000000000 *pde = f000eef3f000eef3 May 18 17:09:36 gonzo kernel: Oops: 0000 [#1] SMP May 18 17:09:36 gonzo kernel: Modules linked in: r8169 evdev May 18 17:09:36 gonzo kernel: CPU: 1 PID: 5086 Comm: btrfs-qgroup-re Not tainted 3.14.1 #1 May 18 17:09:36 gonzo kernel: Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77N-WIFI, BIOS F4 07/31/2013 May 18 17:09:36 gonzo kernel: task: f2afbc20 ti: ed8d6000 task.ti: ed8d6000 May 18 17:09:36 gonzo kernel: EIP: 0060:[<c14698c0>] EFLAGS: 00010292 CPU: 1 May 18 17:09:36 gonzo kernel: EIP is at ulist_next+0x10/0x40 May 18 17:09:36 gonzo kernel: EAX: 00000000 EBX: 00000004 ECX: 80240011 EDX: ed8d7e6c May 18 17:09:36 gonzo kernel: ESI: f26e4000 EDI: ed8d7f00 EBP: ed8d7e40 ESP: ed8d7e38 May 18 17:09:36 gonzo kernel: DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 May 18 17:09:36 gonzo kernel: CR0: 80050033 CR2: 00000004 CR3: 01fc7000 CR4: 001407f0 May 18 17:09:36 gonzo kernel: Stack: May 18 17:09:36 gonzo kernel: 00000000 f26e4000 ed8d7e7c c14685aa 0e4dc000 00000a23 00000000 00000001 May 18 17:09:36 gonzo kernel: f2827f50 f2827f60 00000000 f26e4000 ef680000 eaccc950 00000cd4 00000000 May 18 17:09:36 gonzo kernel: ed8d7f00 ed8d7f10 c146a740 0e4dc000 00000a23 00000000 00000001 ed8d7f00 May 18 17:09:36 gonzo kernel: Call Trace: May 18 17:09:36 gonzo kernel: [<c14685aa>] btrfs_find_all_roots+0x5a/0xf0 May 18 17:09:36 gonzo kernel: [<c146a740>] btrfs_qgroup_rescan_worker+0x2b0/0x660 May 18 17:09:36 gonzo kernel: [<c143a496>] worker_loop+0x76/0x3f0 May 18 17:09:36 gonzo kernel: [<c10aab18>] ? __wake_up_common+0x48/0x70 May 18 17:09:36 gonzo kernel: [<c109341c>] kthread+0xac/0xd0 May 18 17:09:36 gonzo kernel: [<c143a420>] ? btrfs_queue_worker+0x2c0/0x2c0 May 18 17:09:36 gonzo kernel: [<c1b0c437>] ret_from_kernel_thread+0x1b/0x28 May 18 17:09:36 gonzo kernel: [<c1093370>] ? __kthread_parkme+0x60/0x60 May 18 17:09:36 gonzo kernel: Code: 89 1c 24 e8 73 fe ff ff 8b 5d f8 8b 75 fc c9 c3 8d 74 26 00 8d bc 27 00 00 00 00 55 89 e5 83 ec 08 89 1c 24 89 74 24 04 8d 58 04 <8b> 48 04 31 c0 39 cb 74 0b 8b 32 85 f6 75 11 89 0a 8d 41 f0 8b May 18 17:09:36 gonzo kernel: EIP: [<c14698c0>] ulist_next+0x10/0x40 SS:ESP 0068:ed8d7e38 May 18 17:09:36 gonzo kernel: CR2: 0000000000000004 May 18 17:09:36 gonzo kernel: ---[ end trace 45ab777217abb631 ]--- --------------- # btrfsck /dev/mapper/sda2-open Checking filesystem on /dev/mapper/sda2-open UUID: 8cb470e6-13ae-4e8a-aeef-e30942cc1072 checking extents checking free space cache checking fs roots checking csums checking root refs found 1165534378737 bytes used err is 0 total csum bytes: 2929733560 total tree bytes: 4212686848 total fs tree bytes: 766558208 total extent tree bytes: 282804224 btree space waste bytes: 369335816 file data blocks allocated: 3284956061696 referenced 3305002033152 Btrfs v3.14.1 -- 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