Shinichiro, On 6/13/22 19:23, Keith Busch wrote: > On Tue, Jun 14, 2022 at 01:09:07AM +0000, Shinichiro Kawasaki wrote: >> (CC+: linux-pci) >> On Jun 11, 2022 / 16:34, Yi Zhang wrote: >>> On Fri, Jun 10, 2022 at 10:49 PM Keith Busch <kbusch@xxxxxxxxxx> wrote: >>>> >>>> And I am not even sure this is real. I don't know yet why this is showing up >>>> only now, but this should fix it: >>> >>> Hi Keith >>> >>> Confirmed the WARNING issue was fixed with the change, here is the log: >> >> Thanks. I also confirmed that Keith's change to add __ATTR_IGNORE_LOCKDEP to >> dev_attr_dev_rescan avoids the fix, on v5.19-rc2. >> >> I took a closer look into this issue and found The deadlock WARN can be >> recreated with following two commands: >> >> # echo 1 > /sys/bus/pci/devices/0000\:00\:09.0/rescan >> # echo 1 > /sys/bus/pci/devices/0000\:00\:09.0/remove >> >> And it can be recreated with PCI devices other than NVME controller, such as >> SCSI controller or VGA controller. Then this is not a storage sub-system issue. >> >> I checked function call stacks of the two commands above. As shown below, it >> looks like ABBA deadlock possibility is detected and warned. > > Yeah, I was mistaken on this report, so my proposal to suppress the warning is > definitely not right. If I run both 'echo' commands in parallel, I see it > deadlock frequently. I'm not familiar enough with this code to any good ideas > on how to fix, but I agree this is a generic pci issue. I think it is worth adding a testcase to blktests to make sure these future releases will test this. -ck
