On Tue, Mar 30, 2021 at 08:05:56PM +0200, Markus Schaaf wrote: > Hi all, > > on one of my machines I'm seeing these warnings a lot lately: > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 314 at fs/fs-writeback.c:2472 > __writeback_inodes_sb_nr+0xb8/0xd0 > Modules linked in: iTCO_wdt wireguard curve25519_x86_64 libchacha20poly1305 > intel_pmc_bxt iTCO_vendor_support chacha_x86_64 poly1305_x86_64 libblake2s > blake2s_x86_64 ip6_udp_tunnel udp_tunnel libcurve25519_generic libchacha > libblake2s_generic psmouse joydev mousedev pcspkr i2c_i801 i2c_smbus lpc_ich > iptable_filter xt_nat xt_tcpudp intel_agp intel_gtt iptable_nat nf_nat > qemu_fw_cfg nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 mac_hid vfat fat > auth_rpcgss sunrpc fuse ip_tables x_tables btrfs blake2b_generic libcrc32c > crc32c_generic xor raid6_pq dm_crypt cbc encrypted_keys trusted tpm usbhid > dm_mod virtio_gpu virtio_dma_buf drm_kms_helper syscopyarea sysfillrect > sysimgblt fb_sys_fops cec drm virtio_scsi virtio_balloon virtio_net > virtio_console net_failover agpgart failover crct10dif_pclmul crc32_pclmul > crc32c_intel ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper > serio_raw sr_mod cdrom xhci_pci virtio_pci virtio_rng rng_core > CPU: 1 PID: 314 Comm: btrfs-transacti Tainted: G W > 5.10.26-1-MANJARO #1 > Hardware name: Hetzner vServer, BIOS 20171111 11/11/2017 > RIP: 0010:__writeback_inodes_sb_nr+0xb8/0xd0 > Code: 0f b6 d1 48 8d 74 24 10 e8 35 fc ff ff 48 89 e7 e8 7d fb ff ff 48 8b 44 > 24 48 65 48 2b 04 25 28 00 00 00 75 09 48 83 c4 50 c3 <0f> 0b eb cf e8 df 8c > 75 00 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f > RSP: 0018:ffffb1f5448f7d98 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff961185aa5488 RCX: 0000000000000000 > RDX: 0000000000000002 RSI: 0000000000004b45 RDI: ffff9611b7220000 > RBP: ffff9611b64d3958 R08: ffff961184efc800 R09: 0000000000000140 > R10: ffff9611859e6400 R11: ffff961192af3c10 R12: ffff9611838f7c00 > R13: ffff961185aa5000 R14: ffff961185aa5460 R15: 0000000000011a0f > FS: 0000000000000000(0000) GS:ffff9611fad00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f654bc76b58 CR3: 0000000002c60000 CR4: 00000000003506e0 > Call Trace: > btrfs_commit_transaction+0x448/0xbc0 [btrfs] > ? start_transaction+0xcc/0x5b0 [btrfs] > transaction_kthread+0x143/0x170 [btrfs] > ? btrfs_cleanup_transaction.isra.0+0x560/0x560 [btrfs] > kthread+0x133/0x150 > ? __kthread_bind_mask+0x60/0x60 > ret_from_fork+0x22/0x30 > ---[ end trace 3cefecf5d9d20b50 ]--- > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 758 at fs/fs-writeback.c:2472 > __writeback_inodes_sb_nr+0xb8/0xd0
That bug was introduced in 4.15 as part of a fix for a deadlock bug. It's still there today. Not very high on anyone's TODO list as it's mostly harmless--btrfs can't be umounted during a transaction as the umount itself uses a transaction. The warning doesn't come from btrfs code, so we can't just turn it off. > Modules linked in: iTCO_wdt wireguard curve25519_x86_64 libchacha20poly1305 > intel_pmc_bxt iTCO_vendor_support chacha_x86_64 poly1305_x86_64 libblake2s > blake2s_x86_> > CPU: 0 PID: 758 Comm: journal-offline Tainted: G W > 5.10.26-1-MANJARO #1 > Hardware name: Hetzner vServer, BIOS 20171111 11/11/2017 > RIP: 0010:__writeback_inodes_sb_nr+0xb8/0xd0 > Code: 0f b6 d1 48 8d 74 24 10 e8 35 fc ff ff 48 89 e7 e8 7d fb ff ff 48 8b 44 > 24 48 65 48 2b 04 25 28 00 00 00 75 09 48 83 c4 50 c3 <0f> 0b eb cf e8 df 8c > 75 00 66> > RSP: 0018:ffffb1f540d7fd40 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff961185aa5488 RCX: 0000000000000000 > RDX: 0000000000000002 RSI: 0000000000004be5 RDI: ffff9611b7220000 > RBP: ffff961182209208 R08: ffff961184efc800 R09: 0000000000000140 > R10: ffff9611859e6400 R11: ffff961192af3c10 R12: ffff961183891200 > R13: ffff961185aa5000 R14: ffff961185aa5460 R15: ffff9611b65d5e10 > FS: 00007f654b80e640(0000) GS:ffff9611fac00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f654cf39010 CR3: 0000000003884000 CR4: 00000000003506f0 > Call Trace: > btrfs_commit_transaction+0x448/0xbc0 [btrfs] > ? btrfs_wait_ordered_range+0x1b8/0x210 [btrfs] > ? btrfs_sync_file+0x2b8/0x4e0 [btrfs] > btrfs_sync_file+0x343/0x4e0 [btrfs] > __x64_sys_fsync+0x34/0x60 > do_syscall_64+0x33/0x40 Normally you need to mount -o flushoncommit to trigger this warning. Maybe sync is triggering it too? > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7f654cf26deb > Code: 4a 00 00 00 0f 05 48 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 > 33 f7 ff ff 8b 7c 24 0c 41 89 c0 b8 4a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 > 35 44 89> > RSP: 002b:00007f654b80db10 EFLAGS: 00000293 ORIG_RAX: 000000000000004a > RAX: ffffffffffffffda RBX: 00005636c966b410 RCX: 00007f654cf26deb > RDX: 0000000000000002 RSI: 00007f654d169d43 RDI: 0000000000000016 > RBP: 00007f654d16c6f0 R08: 0000000000000000 R09: 00007f654b80e640 > R10: 0000000000000003 R11: 0000000000000293 R12: 0000000000000002 > R13: 00007ffc8bd7461f R14: 0000000000000000 R15: 00007f654b80e640 > ---[ end trace 3cefecf5d9d20b84 ]--- > > This is a KVM guest on an AMD host. A similar machine on an Intel host > doesn't show this. > There is a single BTRFS filesystem on LUKS. It has been created like: > > mkfs.btrfs --csum blake2 -d single -m single /dev/mapper/rootfs > > I've tested Manjaro's 5.11.10 kernel too. No change. btrfs-check (5.11.1) > shows nothing. > I've even recreated the filesystem. No change. Maybe the machine without > warnings uses > the default hash. How can I find out? > > Thanks! > Markus
