Re: [PATCH 6.12 0/6] Backport of XFS umount hang fixes

[Sasha Levin]

> Backport of this series:
> https://lore.kernel.org/all/20250625224957.1436116-1-david@xxxxxxxxxxxxx/

This is about all five series (6.12, 6.6, 6.1, 5.15 and 5.10).

6.12 looks good. On 6.6, 6.1, 5.15 and 5.10 there are two problems:

1. d2fe5c4c8d25 ("xfs: rearrange code in xfs_buf_item.c") turns the
   bli_refcount early return in xfs_buf_item_relse(), added by
   575689fc0ffa ("xfs: fix super block buf log item UAF during force
   shutdown"), into ASSERT(refcount == 0). Mainline only gets away with
   that because of 3762113b597f ("xfs: don't lose solo superblock
   counter update transactions"), which 6.12 has and the four older
   trees don't, so the superblock buf log item UAF on forced shutdown
   comes back there. Either keep the early return on those trees, or
   backport that commit first.

2. d62016b1a2df ("xfs: avoid dquot buffer pin deadlock") fixes a
   deadlock that needs a40fe30868ba ("xfs: separate dquot buffer reads
   from xfs_dqflush"), which those four trees also lack. There it only
   changes behaviour: the dquot shrinker stops writing back dirty
   dquots. The patches after it apply without it.

None of the series has an XFS review yet. Could you resend with
linux-xfs@xxxxxxxxxxxxxxx and the XFS maintainers of each stable tree
on Cc (Catherine Hoang and Chandan Babu R for 6.6, Leah Rumancik for
6.1 and 5.15, Amir Goldstein for 5.10)?

-- 
Thanks,
Sasha