Additional information about this (from the memory dump that I was able to get):
crash> gdb list *(wb_timer_fn+0x44) 0xffffffff991abcc4 is in wb_timer_fn (/build/impish/block/blk-wbt.c:237). 235 static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat) 236 { 237 struct backing_dev_info *bdi = rwb->rqos.q->disk->bdi; 238 struct rq_depth *rqd = &rwb->rq_depth; 239 u64 thislat; It looks like rwb->rqos.q->disk was NULL, likely the callback wb_timer_fn() was executed after a block device has been unregistered... probably a missing del_timer_sync() somewhere in the code? This is also confirmed by: [ 119.987108] BUG: kernel NULL pointer dereference, address: 0000000000000098 0x98 in hex is 152 and looking at struct gendisk, offset 152 is .bdi: crash> struct gendisk.bdi struct gendisk { [152] struct backing_dev_info *bdi; } -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1947557 Title: kernel panic: NULL pointer dereference in wb_timer_f() To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1947557/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs