> I have not root cause this yet, but would like share some findings from > the vmcore Dan shared. From what i can see, this doesn't look like a md > issue, but something wrong with block layer or below. Below is one other thing I found that might be of interest. This is from the original email thread [1] that was linked to in the original issue from 2022, which the change in question reverts: On 2022-09-02 17:46, Logan Gunthorpe wrote: > I've made some progress on this nasty bug. I've got far enough to know it's not > related to the blk-wbt or the block layer. > > Turns out a bunch of bios are stuck queued in a blk_plug in the md_raid5 > thread while that thread appears to be stuck in an infinite loop (so it never > schedules or does anything to flush the plug). > > I'm still debugging to try and find out the root cause of that infinite loop, > but I just wanted to send an update that the previous place I was stuck at > was not correct. > > Logan This certainly sounds like it has some similarities to what we are seeing when that change is reverted. The md0_raid5 thread appears to be in an infinite loop, consuming 100% CPU, but not actually doing any work. -- Dan [1] https://lore.kernel.org/r/7f3b87b6-b52a-f737-51d7-a4eec5c44112@xxxxxxxxxxxx
