linux-kernel - Re: [GIT PULL] 9p cache=mmap regression fix (for 6.18-rc3)

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Message-ID: <39116c81-1798-4cc1-945c-a05d0ac7d8d9@maowtm.org>
Date: Wed, 22 Oct 2025 00:34:13 +0100
From: Tingmao Wang <m@...wtm.org>
To: Dominique Martinet <asmadeus@...ewreck.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Song Liu <song@...nel.org>, Andrii Nakryiko <andrii.nakryiko@...il.com>,
 Eric Van Hensbergen <ericvh@...nel.org>, Latchesar Ionkov
 <lucho@...kov.net>, Christian Schoenebeck <linux_oss@...debyte.com>,
 Alexei Starovoitov <ast@...nel.org>, linux-kernel@...r.kernel.org,
 v9fs@...ts.linux.dev, bpf@...r.kernel.org
Subject: Re: [GIT PULL] 9p cache=mmap regression fix (for 6.18-rc3)

On 10/22/25 00:16, Dominique Martinet wrote:
> Hi Linus,
> 
> We had a regression with cache=mmap that impacted quite a few people so
> I'm sending a fix less than a couple of hours after making the commit.
> 
> If it turns out there are other side effects I'd suggest just reverting
> commit 290434474c33 ("fs/9p: Refresh metadata in d_revalidate for
> uncached mode too") first, but the fix is rather minimal so I think it's
> ok to try falling forward -- let me know if you prefer a revert and I'll
> send one instead (there's a minor conflict)

See the reply to the original patch [1] (posted right after, and before
seeing, this message) - there is indeed more side effects, and I wouldn't
mind a revert for now.  0172a934747f ("fs/9p: Invalidate dentry if inode
type change detected in cached mode") will need to be reverted too.

[1]: https://lore.kernel.org/v9fs/6c74ad63-3afc-4549-9ac6-494b9a63e839@maowtm.org/