syzbot


INFO: task hung in del_gendisk
Status: upstream: reported C repro on 2021/07/11 15:55
Reported-by: syzbot+0fe7752e52337864d29b@syzkaller.appspotmail.com
Fix commit: 68c9417b193d nbd: do del_gendisk() asynchronously for NBD_DESTROY_ON_DISCONNECT
Patched on: [ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-riscv64 ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386]
First crash: 71d, last: 34d

Cause bisection: introduced by (bisect log) :
commit c76f48eb5c084b1e15c931ae8cc1826cd771d70d
Author: Christoph Hellwig <hch@lst.de>
Date: Tue Apr 6 06:22:56 2021 +0000

  block: take bd_mutex around delete_partitions in del_gendisk

Crash: possible deadlock in del_gendisk (log)
Repro: C syz .config

Sample crash report:

Fix bisection attempts:
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2021/08/06 17:00 upstream 902e7f373fff 4846d5c1 .config log report syz C
Crashes (5):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2021/07/07 15:40 upstream 3dbdb38e2869 4846d5c1 .config log report syz C INFO: task hung in del_gendisk
ci-upstream-kasan-gce-smack-root 2021/07/07 10:45 upstream 3dbdb38e2869 4846d5c1 .config log report info INFO: task hung in del_gendisk
ci-upstream-linux-next-kasan-gce-root 2021/08/13 14:12 linux-next 4b358aabb93a 3fd2ea69 .config log report info INFO: task hung in del_gendisk
ci-upstream-linux-next-kasan-gce-root 2021/08/12 21:41 linux-next 9b992972fb9c 3fd2ea69 .config log report info INFO: task hung in del_gendisk
ci-upstream-linux-next-kasan-gce-root 2021/08/11 08:55 linux-next 92d00774360d 6972b106 .config log report info INFO: task hung in del_gendisk