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.
