From: Trond Myklebust <trondmy@kernel.org>
To: Ben Roberts <ben.roberts@gsacapital.com>,
Benjamin Coddington <ben.coddington@hammerspace.com>
Cc: Anna Schumaker <anna@kernel.org>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] pNFS: deadlock in pnfs_send_layoutreturn
Date: Wed, 22 Apr 2026 08:52:04 -0400 [thread overview]
Message-ID: <1821e8c9b3d7f5aff9447f719e6f94932b68a79d.camel@kernel.org> (raw)
In-Reply-To: <AM8PR04MB776494AB2547E8DEE4C6186D8A2D2@AM8PR04MB7764.eurprd04.prod.outlook.com>
On Wed, 2026-04-22 at 10:46 +0000, Ben Roberts wrote:
> Hi Ben,
>
> > The kzalloc failure is definitely a rarely-used/tested path, so its
> > possible
> > there's an issue there no one has seen yet, but from what I can see
> > it looks
> > like every call to pnfs_send_layoutreturn() first calls
> > pnfs_prepare_layoutreturn(), which already clears
> > NFS_LAYOUT_RETURN_REQUESTED. I don't see how you can end up with
> > another
> > proccess seeing the flag.
>
I had first applied this patch, however when looking more closely, it
seems that it will also be defeated by the by the loop in
pnfs_clear_layoutreturn_info() that checks if there are any layouts
that need returning, and resets NFS_LAYOUT_RETURN_REQUESTED.
> Understood, thank you for the feedback here. I withdraw the patch
> request and
> will take this back to the drawing board. Likely removing the patch
> from local
> systems and looking to capture more useful diagnostics if/when the
> problem
> reoccurs.
>
> > There's at least one body of work in this area that your systems
> > don't yet have:
> > https://lore.kernel.org/linux-nfs/20240613050055.854323-1-trond.myklebust@hammerspace.com/
>
> For what it's worth, I checked this patch set and the changes are
> almost
> completely present in the EL source. Patch 2 is only partially
> applied.
>
> Ben Roberts
prev parent reply other threads:[~2026-04-22 12:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-08 12:25 [PATCH v2] pNFS: deadlock in pnfs_send_layoutreturn Ben Roberts
2026-04-10 14:30 ` Benjamin Coddington
2026-04-17 10:17 ` Ben Roberts
2026-04-17 16:19 ` Benjamin Coddington
2026-04-22 10:46 ` Ben Roberts
2026-04-22 12:52 ` Trond Myklebust [this message]
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