Re: 5.14.9 aarch64 OOPS Workqueue: btrfs-delalloc btrfs_work_helper

[Nikolay Borisov <nborisov@suse.com>]

On 22.10.21 г. 5:36, Chris Murphy wrote:
> OK I have a vmcore file:
> https://dustymabe.fedorapeople.org/bz2011928-vmcore/
> 
> lib/modules/5.14.10-300.fc35.aarch64/vmlinuz
> https://drive.google.com/file/d/1xXM8XGRi_Wzyupbm4MSNteF0rwUzO4GE/view?usp=sharing
> 

So the problem is we have a null inode:


crash> struct async_chunk ffff00012a78eb08
struct async_chunk {
  inode = 0x0,
  locked_page = 0xfffffc000508c240,
  start = 0,
  end = 4095,
  write_flags = 0,
  extents = {
    next = 0xffff00012a78eb30,
    prev = 0xffff00012a78eb30
  },
  blkcg_css = 0x0,
  work = {
    func = 0xffffd7c4c03c05c0 <async_cow_start>,
    ordered_func = 0xffffd7c4c03c1bf0 <async_cow_submit>,
    ordered_free = 0xffffd7c4c03be2e0 <async_cow_free>,
    normal_work = {
      data = {
        counter = 256
      },
      entry = {
        next = 0xffff00012a78eb68,
        prev = 0xffff00012a78eb68
      },
      func = 0xffffd7c4c03f9e84 <btrfs_work_helper>
    },
    ordered_list = {
      next = 0xffff00012a78ee80,
      prev = 0xffff0000c6d83510
    },
    wq = 0xffff0000c6d83500,
    flags = 3
  },
  pending = 0xffff00012a78eb00
}


But this makes no sense since before submit_compressed_extents is called
we have an explicit check for async_hunk->inode presence but AFAICS this
is not done in a concurrent context. So this either leaves some hw issue
or some race which manifests due to ARM's weak mm.

> 
> --
> Chris Murphy
>