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blk-wbt hang issue - Coggle Diagram
blk-wbt hang issue
ideas
is there such issue with none?
yes
what are the 8 requests in scheduler queue?
possible reasons
not freed from scheduler queue?
rq->sched_tags are changed?
the problem is triggered in extreme memory less situation
start lockdep and see if there is deadlock?
memory deadlock
observation
blk-mq
8 in-flight requests in scheduler queue
flush plug list?
how to trace them?
dump them from dbgfs
trace their allocator tasks
cgroup related?
no in-flight rqs in driver tag
devices
virtio-blk
scsi
scheduler
deadline or none
when the issue is triggered, queue is still good
blk-wbt
12 bios are pending on wbt_wait
system
all ram and swap space are used up basically
memory allocation failure
workloads
free
wbt wait inside page fault
stress
wbt wait inside page fault
multiple thread