Hello, Two of my machines constantly crash with a double fault like this: 1146 <0>[33685.629591] traps: PANIC: double fault, error_code: 0x0 1147 <4>[33685.629593] double fault: 0000 [#1] SMP NOPTI 1148 <4>[33685.629594] CPU: 10 PID: 2118287 Comm: kworker/10:0 Tainted: P OE 5.11.8-051108-generic #202103200636 1149 <4>[33685.629595] Hardware name: ASUSTeK COMPUTER INC. KRPG-U8 Series/KRPG-U8 Series, BIOS 4201 09/25/2020 1150 <4>[33685.629595] Workqueue: xfs-conv/md12 xfs_end_io [xfs] 1151 <4>[33685.629596] RIP: 0010:__slab_free+0x23/0x340 1152 <4>[33685.629597] Code: 4c fe ff ff 0f 1f 00 0f 1f 44 00 00 55 48 89 e5 41 57 49 89 cf 41 56 49 89 fe 41 55 41 54 49 89 f4 53 48 83 e4 f0 48 83 ec 70 <48> 89 54 24 28 0f 1f 44 00 00 41 8b 46 28 4d 8b 6c 24 20 49 8b 5c 1153 <4>[33685.629598] RSP: 0018:ffffa9bc00848fa0 EFLAGS: 00010086 1154 <4>[33685.629599] RAX: ffff94c04d8b10a0 RBX: ffff94437a34a880 RCX: ffff94437a34a880 1155 <4>[33685.629599] RDX: ffff94437a34a880 RSI: ffffcec745e8d280 RDI: ffff944300043b00 1156 <4>[33685.629599] RBP: ffffa9bc00849040 R08: 0000000000000001 R09: ffffffff82a5d6de 1157 <4>[33685.629600] R10: 0000000000000001 R11: 000000009c109000 R12: ffffcec745e8d280 1158 <4>[33685.629600] R13: ffff944300043b00 R14: ffff944300043b00 R15: ffff94437a34a880 1159 <4>[33685.629601] FS: 0000000000000000(0000) GS:ffff94c04d880000(0000) knlGS:0000000000000000 1160 <4>[33685.629601] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 1161 <4>[33685.629602] CR2: ffffa9bc00848f98 CR3: 000000014d04e000 CR4: 0000000000350ee0 1162 <4>[33685.629602] Call Trace: 1163 <4>[33685.629603] <IRQ> 1164 <4>[33685.629603] ? kfree+0x3bc/0x3e0 1165 <4>[33685.629603] ? mempool_kfree+0xe/0x10 1166 <4>[33685.629603] ? mempool_kfree+0xe/0x10 1167 <4>[33685.629604] ? mempool_free+0x2f/0x80 1168 <4>[33685.629604] ? md_end_io+0x4a/0x70 1169 <4>[33685.629604] ? bio_endio+0xdc/0x130 1170 <4>[33685.629605] ? bio_chain_endio+0x2d/0x40 1171 <4>[33685.629605] ? md_end_io+0x5c/0x70 1172 <4>[33685.629605] ? bio_endio+0xdc/0x130 1173 <4>[33685.629605] ? bio_chain_endio+0x2d/0x40 1174 <4>[33685.629606] ? md_end_io+0x5c/0x70 1175 <4>[33685.629606] ? bio_endio+0xdc/0x130 1176 <4>[33685.629606] ? bio_chain_endio+0x2d/0x40 1177 <4>[33685.629607] ? md_end_io+0x5c/0x70 ... repeated ... 1436 <4>[33685.629677] ? bio_endio+0xdc/0x130 1437 <4>[33685.629677] ? bio_chain_endio+0x2d/0x40 1438 <4>[33685.629677] ? md_end_io+0x5c/0x70 1439 <4>[33685.629677] ? bio_endio+0xdc/0x130 1440 <4>[33685.629678] ? bio_chain_endio+0x2d/0x40 1441 <4>[33685.629678] ? md_ 1442 <4>[33685.629679] Lost 357 message(s)! This happens on: 5.11.8-051108-generic #202103200636 SMP Sat Mar 20 11:17:32 UTC 2021 and on 5.8.0-44-generic #50~20.04.1-Ubuntu (https://changelogs.ubuntu.com/changelogs/pool/main/l/linux/linux_5.8.0-44.50/changelog) which contains backported https://github.com/torvalds/linux/commit/41d2d848e5c09209bdb57ff9c0ca34075e22783d ("md: improve io stats accounting"). The 5.8.18-050818-generic #202011011237 SMP Sun Nov 1 12:40:15 UTC 2020 which does not contain above suspected change does not crash. If there's a better way/place to report this bug just let me know. If not, here are steps to reproduce: 1. Create a RAID 0 device using three Micron_9300_MTFDHAL7T6TDP disks. mdadm --create --verbose /dev/md12 --level=stripe --raid-devices=3 /dev/nvme0n1p1 /dev/nvme1n1p1 /dev/nvme2n1p1 2. Setup xfs on it: mkfs.xfs /dev/md12 and mount it 3. Write to a file on this filesystem: while true; do rm -rf /mnt/md12/crash* ; for i in `seq 8`; do dd if=/dev/zero of=/mnt/md12/crash$i bs=32K count=50000000 & done; wait; done Wait for a crash (usually less than 20 min). I couldn't reproduce it with a single dd process (maybe I have to wait a little longer), but a single cat /very/large/file/on/cephfs/over100GbE > /mnt/md12/crash is enough for this double fault to occur. More info: This long mempool_kfree - md_end_io - * -md_end_io stack trace looks always the same, but the panic occurs in different places: pstore/6948115143318/dmesg.txt-<4>[545649.087998] CPU: 88 PID: 0 Comm: swapper/88 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6948377398316/dmesg.txt-<4>[11275.914909] CPU: 14 PID: 0 Comm: swapper/14 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6948532816002/dmesg.txt-<4>[33685.629594] CPU: 10 PID: 2118287 Comm: kworker/10:0 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6948532816002/dmesg.txt-<4>[33685.629595] Workqueue: xfs-conv/md12 xfs_end_io [xfs] pstore/6948855849083/dmesg.txt-<4>[42934.321129] CPU: 85 PID: 0 Comm: swapper/85 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6948876331782/dmesg.txt-<4>[ 3475.020672] CPU: 86 PID: 0 Comm: swapper/86 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6949083860307/dmesg.txt-<4>[43048.254375] CPU: 45 PID: 0 Comm: swapper/45 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6949091775931/dmesg.txt-<4>[ 1150.790240] CPU: 64 PID: 0 Comm: swapper/64 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6949123356826/dmesg.txt-<4>[ 6963.858253] CPU: 6 PID: 51 Comm: kworker/6:0 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6949123356826/dmesg.txt-<4>[ 6963.858255] Workqueue: ceph-msgr ceph_con_workfn [libceph] pstore/6949123356826/dmesg.txt-<4>[ 6963.858253] CPU: 6 PID: 51 Comm: kworker/6:0 Tainted: P OE 5.11.8-051108-generic #202103200636 pstore/6949123356826/dmesg.txt-<4>[ 6963.858255] Workqueue: ceph-msgr ceph_con_workfn [libceph] pstore/6949152322085/dmesg.txt-<4>[ 6437.077874] CPU: 59 PID: 0 Comm: swapper/59 Tainted: P OE 5.11.8-051108-generic #202103200636 cat /proc/cmdline BOOT_IMAGE=/vmlinuz-5.11.8-051108-generic root=/dev/mapper/ubuntu--vg-ubuntu--lv ro net.ifnames=0 biosdevname=0 strict-devmem=0 mitigations=off iommu=pt cat /proc/cpuinfo model name : AMD EPYC 7552 48-Core Processor cat /proc/mounts /dev/md12 /mnt/ssd1 xfs rw,noatime,attr2,inode64,logbufs=8,logbsize=32k,sunit=1024,swidth=3072,prjquota 0 0 Let me know if you need more information. Best regards, Paweł Wiejacha
