From: Christoph Hellwig <hch@infradead.org>
To: Mike Snitzer <snitzer@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna.schumaker@oracle.com>,
linux-nfs@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH for-akpm for-6.14-rcX] NFS: fix nfs_release_folio() to not call nfs_wb_folio() from kcompactd
Date: Wed, 26 Feb 2025 06:58:11 -0800 [thread overview]
Message-ID: <Z78sA-7_u5SyuFSw@infradead.org> (raw)
In-Reply-To: <20250225003301.25693-1-snitzer@kernel.org>
On Mon, Feb 24, 2025 at 07:33:01PM -0500, Mike Snitzer wrote:
> Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for
> it so nfs_release_folio() can skip calling nfs_wb_folio() from
> kcompactd.
>
> Otherwise NFS can deadlock waiting for kcompactd enduced writeback
> which recurses back to NFS (which triggers writeback to NFSD via
> NFS loopback mount on the same host, NFSD blocks waiting for XFS's
> call to __filemap_get_folio):
Having a flag for a specific kernel thread feels wrong. I'm not an
expert in this area, but as fast as I can tell the problem is that
kcompactd should be calling into ->release_folio without __GFP_IO
set.
next prev parent reply other threads:[~2025-02-26 14:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-25 0:33 [PATCH for-akpm for-6.14-rcX] NFS: fix nfs_release_folio() to not call nfs_wb_folio() from kcompactd Mike Snitzer
2025-02-25 2:20 ` [PATCH v2 for-akpm for-6.14-rcX] NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback Mike Snitzer
2025-02-25 6:53 ` Andrew Morton
2025-02-25 17:02 ` Mike Snitzer
2025-02-25 20:19 ` [PATCH v3 " Mike Snitzer
2025-02-25 20:28 ` Mike Snitzer
2025-02-26 14:58 ` Christoph Hellwig [this message]
2025-02-26 15:44 ` [PATCH for-akpm for-6.14-rcX] NFS: fix nfs_release_folio() to not call nfs_wb_folio() from kcompactd Mike Snitzer
2025-02-26 15:55 ` Mike Snitzer
2025-02-26 17:22 ` Trond Myklebust
2025-02-26 22:02 ` Andrew Morton
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