Thanks. Trying gdb helped me find the answer. I needed to install the kernel-debuginfo-3.15.8-200.fc20.x86_64 package via yum. >From addr2line: > bch_btree_node_read_done+0x4c > drivers/md/bcache/btree.c:207 Here'a a snippet from gdb: > (gdb) list *(bch_btree_node_read_done+0x4c) > 0x65fc is in bch_btree_node_read_done (drivers/md/bcache/btree.c:207). > 202 struct bset *i = btree_bset_first(b); > 203 struct btree_iter *iter; > 204 > 205 iter = mempool_alloc(b->c->fill_iter, GFP_NOWAIT); > 206 iter->size = b->c->sb.bucket_size / b->c->sb.block_size; > 207 iter->used = 0; > 208 > 209 #ifdef CONFIG_BCACHE_DEBUG > 210 iter->b = &b->keys; > 211 #endif This doesn't make any sense to me. If iter was null I would expect line 206 to blow up first. --Larkin On 8/13/2014 12:41 PM, Slava Pestov wrote: > You can try to use gdb: > > gdb /lib/modules/.../foo.ko > > list *(bch_btree_node_read_done+0x4c) > > > On Wed, Aug 13, 2014 at 9:40 AM, Larkin Lowrey > <llowrey@xxxxxxxxxxxxxxxxx> wrote: >> This is making be feel very dumb. I've googled extensively but can't >> figure out how to run addr2line for a module. >> >> I'm running Fedora 20 and the kernel did not have debugging symbols. I >> downloaded the version with symbols but I don't know if the addresses >> are going to be the same. Bcache is a module for me and that's where >> things get tricky. Do you have any tips? >> >> --Larkin >> >> On 8/13/2014 12:04 AM, Kent Overstreet wrote: >>> Any chance you could do an addr2line and get me the exact line where >>> it happened? >>> >>> On Aug 12, 2014 10:02 PM, "Larkin Lowrey" <llowrey@xxxxxxxxxxxxxxxxx >>> <mailto:llowrey@xxxxxxxxxxxxxxxxx>> wrote: >>> >>> I got an oops while doing some heavy I/O. I have an md raid10 cache >>> device (4 SSDs) and 3 md raid5/6 backing devices. This setup has been >>> well behaved for about 6 months. >>> >>> If this isn't a known issue is there anything I can do to provide more >>> useful information? >>> >>> I'm running kernel 3.15.8-200.fc20.x86_64. >>> >>> [210884.047249] BUG: unable to handle kernel NULL pointer >>> dereference at 0000000000000008 >>> [210884.055605] IP: [<ffffffffa01625fc>] >>> bch_btree_node_read_done+0x4c/0x450 [bcache] >>> [210884.063723] PGD 0 >>> [210884.066053] Oops: 0002 [#1] SMP >>> [210884.069610] Modules linked in: lp parport binfmt_misc >>> ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat xt_CHECKSUM >>> iptable_mangle tun bridge stp llc xt_multiport ebtable_nat >>> ebtables hwmon_vid ip6t_REJECT nf_conntrack_ipv6 nf_conntrack_ipv4 >>> nf_defrag_ipv6 nf_defrag_ipv4 ip6table_filter xt_conntrack >>> ip6_tables nf_conntrack keyspan ezusb kvm_amd kvm crct10dif_pclmul >>> crc32_pclmul crc32c_intel ghash_clmulni_intel microcode serio_raw >>> amd64_edac_mod edac_core fam15h_power k10temp edac_mce_amd >>> sp5100_tco i2c_piix4 igb ptp pps_core dca shpchp acpi_cpufreq >>> btrfs bcache raid456 async_raid6_recov async_memcpy async_pq >>> async_xor async_tx xor raid6_pq raid10 i2c_algo_bit drm_kms_helper >>> ttm drm i2c_core mpt2sas mvsas libsas raid_class >>> scsi_transport_sas cpufreq_stats >>> [210884.140704] CPU: 5 PID: 11188 Comm: kworker/5:1 Not tainted >>> 3.15.8-200.fc20.x86_64 #1 >>> [210884.149069] Hardware name: /H8DG6/H8DGi, BIOS 3.0a 07/2 >>> [210884.155280] Workqueue: bcache cache_lookup [bcache] >>> [210884.160531] task: ffff880218633160 ti: ffff8800217b8000 >>> task.ti: ffff8800217b8000 >>> [210884.168502] RIP: 0010:[<ffffffffa01625fc>] >>> [<ffffffffa01625fc>] bch_btree_node_read_done+0x4c/0x450 [bcache] >>> [210884.179105] RSP: 0000:ffff8800217bbbe8 EFLAGS: 00010212 >>> [210884.184806] RAX: 0000000000000400 RBX: ffff880245ec0000 RCX: >>> 0000000000000000 >>> [210884.192480] RDX: 0000000000000000 RSI: ffff880418380000 RDI: >>> 0000000000000246 >>> [210884.200075] RBP: ffff8800217bbc10 R08: 0000000000000000 R09: >>> 0000000000000f6b >>> [210884.207738] R10: 0000000000000000 R11: 0000000000000400 R12: >>> ffff880413d06c00 >>> [210884.215391] R13: 0000000000000000 R14: ffff8800217bbc20 R15: >>> ffff880413d06c00 >>> [210884.222961] FS: 00007f73bacd6880(0000) >>> GS:ffff88021fd40000(0000) knlGS:0000000000000000 >>> [210884.231516] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b >>> [210884.237557] CR2: 0000000000000008 CR3: 0000000001c11000 CR4: >>> 00000000000407e0 >>> [210884.245131] Stack: >>> [210884.247395] ffff880274f4d020 ffff880413d06c00 >>> 0000bfcc44a463f8 ffff8800217bbc20 >>> [210884.255337] ffff880413d06c00 ffff8800217bbc78 >>> ffffffffa0162b68 0000000000000000 >>> [210884.263256] ffff880218633160 0000000000000000 >>> 0000000000000000 0000000000000000 >>> [210884.271234] Call Trace: >>> [210884.273985] [<ffffffffa0162b68>] >>> bch_btree_node_read+0x168/0x190 [bcache] >>> [210884.281258] [<ffffffffa0163f69>] >>> bch_btree_node_get+0x169/0x290 [bcache] >>> [210884.288377] [<ffffffffa01642f5>] >>> bch_btree_map_keys_recurse+0xd5/0x1d0 [bcache] >>> [210884.296311] [<ffffffffa016dcb0>] ? >>> cached_dev_congested+0x180/0x180 [bcache] >>> [210884.303953] [<ffffffff8135b204>] ? >>> call_rwsem_down_read_failed+0x14/0x30 >>> [210884.311158] [<ffffffffa01673f7>] >>> bch_btree_map_keys+0x127/0x150 [bcache] >>> [210884.318273] [<ffffffffa016dcb0>] ? >>> cached_dev_congested+0x180/0x180 [bcache] >>> [210884.325826] [<ffffffffa016e7f5>] cache_lookup+0xf5/0x1f0 [bcache] >>> [210884.332325] [<ffffffff810a4af6>] process_one_work+0x176/0x430 >>> [210884.338427] [<ffffffff810a578b>] worker_thread+0x11b/0x3a0 >>> [210884.344282] [<ffffffff810a5670>] ? rescuer_thread+0x3b0/0x3b0 >>> [210884.350447] [<ffffffff810ac528>] kthread+0xd8/0xf0 >>> [210884.355615] [<ffffffff810ac450>] ? insert_kthread_work+0x40/0x40 >>> [210884.362017] [<ffffffff816ff93c>] ret_from_fork+0x7c/0xb0 >>> [210884.367756] [<ffffffff810ac450>] ? insert_kthread_work+0x40/0x40 >>> [210884.374234] Code: 08 01 00 00 48 8b b8 58 cb 00 00 e8 bf 25 01 >>> e1 49 8b b4 24 80 00 00 00 49 89 c5 31 d2 0f b7 86 32 04 00 00 66 >>> f7 b6 30 04 00 00 <49> c7 45 08 00 00 00 00 0f b7 c0 49 89 45 00 >>> 48 8b 43 10 48 85 >>> [210884.395405] RIP [<ffffffffa01625fc>] >>> bch_btree_node_read_done+0x4c/0x450 [bcache] >>> [210884.403389] RSP <ffff8800217bbbe8> >>> [210884.407171] CR2: 0000000000000008 >>> [210884.411233] ---[ end trace 0064e6abfd068c85 ]--- >>> [210884.416352] BUG: unable to handle kernel paging request at >>> ffffffffffffffd8 >>> [210884.423871] IP: [<ffffffff810acb10>] kthread_data+0x10/0x20 >>> [210884.429915] PGD 1c14067 PUD 1c16067 PMD 0 >>> >>> --Larkin >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe >>> linux-bcache" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> <mailto:majordomo@xxxxxxxxxxxxxxx> >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-bcache" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-bcache" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
