* [PATCH 6.6.y 2/2] NFS: Fix a deadlock involving nfs_release_folio()
@ 2026-02-24 7:02 Li hongliang
2026-03-19 11:12 ` Patch "NFS: Fix a deadlock involving nfs_release_folio()" has been added to the 6.6-stable tree gregkh
0 siblings, 1 reply; 2+ messages in thread
From: Li hongliang @ 2026-02-24 7:02 UTC (permalink / raw)
To: gregkh, stable, trond.myklebust
Cc: patches, linux-kernel, anna, linux-nfs, wangzhaolong
From: Trond Myklebust <trond.myklebust@hammerspace.com>
[ Upstream commit cce0be6eb4971456b703aaeafd571650d314bcca ]
Wang Zhaolong reports a deadlock involving NFSv4.1 state recovery
waiting on kthreadd, which is attempting to reclaim memory by calling
nfs_release_folio(). The latter cannot make progress due to state
recovery being needed.
It seems that the only safe thing to do here is to kick off a writeback
of the folio, without waiting for completion, or else kicking off an
asynchronous commit.
Reported-by: Wang Zhaolong <wangzhaolong@huaweicloud.com>
Fixes: 96780ca55e3c ("NFS: fix up nfs_release_folio() to try to release the page")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
[ Minor conflict resolved. ]
Signed-off-by: Li hongliang <1468888505@139.com>
---
fs/nfs/file.c | 3 ++-
fs/nfs/nfstrace.h | 3 +++
fs/nfs/write.c | 33 +++++++++++++++++++++++++++++++++
include/linux/nfs_fs.h | 1 +
4 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 9b6f4cc4d582..cf16ee710d42 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -459,7 +459,8 @@ static bool nfs_release_folio(struct folio *folio, gfp_t gfp)
if ((current_gfp_context(gfp) & GFP_KERNEL) != GFP_KERNEL ||
current_is_kswapd() || current_is_kcompactd())
return false;
- if (nfs_wb_folio(folio_file_mapping(folio)->host, folio) < 0)
+ if (nfs_wb_folio_reclaim(folio_file_mapping(folio)->host, folio) < 0 ||
+ folio_test_private(folio))
return false;
}
return nfs_fscache_release_folio(folio, gfp);
diff --git a/fs/nfs/nfstrace.h b/fs/nfs/nfstrace.h
index 004c25f0782b..85224e9369e7 100644
--- a/fs/nfs/nfstrace.h
+++ b/fs/nfs/nfstrace.h
@@ -1033,6 +1033,9 @@ DECLARE_EVENT_CLASS(nfs_folio_event_done,
DEFINE_NFS_FOLIO_EVENT(nfs_aop_readpage);
DEFINE_NFS_FOLIO_EVENT_DONE(nfs_aop_readpage_done);
+DEFINE_NFS_FOLIO_EVENT(nfs_writeback_folio_reclaim);
+DEFINE_NFS_FOLIO_EVENT_DONE(nfs_writeback_folio_reclaim_done);
+
DEFINE_NFS_FOLIO_EVENT(nfs_writeback_folio);
DEFINE_NFS_FOLIO_EVENT_DONE(nfs_writeback_folio_done);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 7b225ef1a284..dc57e67cefcd 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -2121,6 +2121,39 @@ int nfs_wb_folio_cancel(struct inode *inode, struct folio *folio)
return ret;
}
+/**
+ * nfs_wb_folio_reclaim - Write back all requests on one page
+ * @inode: pointer to page
+ * @folio: pointer to folio
+ *
+ * Assumes that the folio has been locked by the caller
+ */
+int nfs_wb_folio_reclaim(struct inode *inode, struct folio *folio)
+{
+ loff_t range_start = folio_pos(folio);
+ size_t len = folio_size(folio);
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_ALL,
+ .nr_to_write = 0,
+ .range_start = range_start,
+ .range_end = range_start + len - 1,
+ .for_sync = 1,
+ };
+ int ret;
+
+ if (folio_test_writeback(folio))
+ return -EBUSY;
+ if (folio_clear_dirty_for_io(folio)) {
+ trace_nfs_writeback_folio_reclaim(inode, range_start, len);
+ ret = nfs_writepage_locked(folio, &wbc);
+ trace_nfs_writeback_folio_reclaim_done(inode, range_start, len,
+ ret);
+ return ret;
+ }
+ nfs_commit_inode(inode, 0);
+ return 0;
+}
+
/**
* nfs_wb_folio - Write back all requests on one page
* @inode: pointer to page
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 832b7e354b4e..86d589070b23 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -608,6 +608,7 @@ extern int nfs_update_folio(struct file *file, struct folio *folio,
extern int nfs_sync_inode(struct inode *inode);
extern int nfs_wb_all(struct inode *inode);
extern int nfs_wb_folio(struct inode *inode, struct folio *folio);
+extern int nfs_wb_folio_reclaim(struct inode *inode, struct folio *folio);
int nfs_wb_folio_cancel(struct inode *inode, struct folio *folio);
extern int nfs_commit_inode(struct inode *, int);
extern struct nfs_commit_data *nfs_commitdata_alloc(void);
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Patch "NFS: Fix a deadlock involving nfs_release_folio()" has been added to the 6.6-stable tree
2026-02-24 7:02 [PATCH 6.6.y 2/2] NFS: Fix a deadlock involving nfs_release_folio() Li hongliang
@ 2026-03-19 11:12 ` gregkh
0 siblings, 0 replies; 2+ messages in thread
From: gregkh @ 2026-03-19 11:12 UTC (permalink / raw)
To: 1468888505, anna, gregkh, patches, trond.myklebust, wangzhaolong
Cc: stable-commits
This is a note to let you know that I've just added the patch titled
NFS: Fix a deadlock involving nfs_release_folio()
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfs-fix-a-deadlock-involving-nfs_release_folio.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
From stable+bounces-217867-greg=kroah.com@vger.kernel.org Tue Feb 24 08:02:54 2026
From: Li hongliang <1468888505@139.com>
Date: Tue, 24 Feb 2026 15:02:37 +0800
Subject: NFS: Fix a deadlock involving nfs_release_folio()
To: gregkh@linuxfoundation.org, stable@vger.kernel.org, trond.myklebust@hammerspace.com
Cc: patches@lists.linux.dev, linux-kernel@vger.kernel.org, anna@kernel.org, linux-nfs@vger.kernel.org, wangzhaolong@huaweicloud.com
Message-ID: <20260224070237.2933965-1-1468888505@139.com>
From: Trond Myklebust <trond.myklebust@hammerspace.com>
[ Upstream commit cce0be6eb4971456b703aaeafd571650d314bcca ]
Wang Zhaolong reports a deadlock involving NFSv4.1 state recovery
waiting on kthreadd, which is attempting to reclaim memory by calling
nfs_release_folio(). The latter cannot make progress due to state
recovery being needed.
It seems that the only safe thing to do here is to kick off a writeback
of the folio, without waiting for completion, or else kicking off an
asynchronous commit.
Reported-by: Wang Zhaolong <wangzhaolong@huaweicloud.com>
Fixes: 96780ca55e3c ("NFS: fix up nfs_release_folio() to try to release the page")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
[ Minor conflict resolved. ]
Signed-off-by: Li hongliang <1468888505@139.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/file.c | 3 ++-
fs/nfs/nfstrace.h | 3 +++
fs/nfs/write.c | 33 +++++++++++++++++++++++++++++++++
include/linux/nfs_fs.h | 1 +
4 files changed, 39 insertions(+), 1 deletion(-)
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -459,7 +459,8 @@ static bool nfs_release_folio(struct fol
if ((current_gfp_context(gfp) & GFP_KERNEL) != GFP_KERNEL ||
current_is_kswapd() || current_is_kcompactd())
return false;
- if (nfs_wb_folio(folio_file_mapping(folio)->host, folio) < 0)
+ if (nfs_wb_folio_reclaim(folio_file_mapping(folio)->host, folio) < 0 ||
+ folio_test_private(folio))
return false;
}
return nfs_fscache_release_folio(folio, gfp);
--- a/fs/nfs/nfstrace.h
+++ b/fs/nfs/nfstrace.h
@@ -1033,6 +1033,9 @@ DECLARE_EVENT_CLASS(nfs_folio_event_done
DEFINE_NFS_FOLIO_EVENT(nfs_aop_readpage);
DEFINE_NFS_FOLIO_EVENT_DONE(nfs_aop_readpage_done);
+DEFINE_NFS_FOLIO_EVENT(nfs_writeback_folio_reclaim);
+DEFINE_NFS_FOLIO_EVENT_DONE(nfs_writeback_folio_reclaim_done);
+
DEFINE_NFS_FOLIO_EVENT(nfs_writeback_folio);
DEFINE_NFS_FOLIO_EVENT_DONE(nfs_writeback_folio_done);
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -2122,6 +2122,39 @@ int nfs_wb_folio_cancel(struct inode *in
}
/**
+ * nfs_wb_folio_reclaim - Write back all requests on one page
+ * @inode: pointer to page
+ * @folio: pointer to folio
+ *
+ * Assumes that the folio has been locked by the caller
+ */
+int nfs_wb_folio_reclaim(struct inode *inode, struct folio *folio)
+{
+ loff_t range_start = folio_pos(folio);
+ size_t len = folio_size(folio);
+ struct writeback_control wbc = {
+ .sync_mode = WB_SYNC_ALL,
+ .nr_to_write = 0,
+ .range_start = range_start,
+ .range_end = range_start + len - 1,
+ .for_sync = 1,
+ };
+ int ret;
+
+ if (folio_test_writeback(folio))
+ return -EBUSY;
+ if (folio_clear_dirty_for_io(folio)) {
+ trace_nfs_writeback_folio_reclaim(inode, range_start, len);
+ ret = nfs_writepage_locked(folio, &wbc);
+ trace_nfs_writeback_folio_reclaim_done(inode, range_start, len,
+ ret);
+ return ret;
+ }
+ nfs_commit_inode(inode, 0);
+ return 0;
+}
+
+/**
* nfs_wb_folio - Write back all requests on one page
* @inode: pointer to page
* @folio: pointer to folio
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -608,6 +608,7 @@ extern int nfs_update_folio(struct file
extern int nfs_sync_inode(struct inode *inode);
extern int nfs_wb_all(struct inode *inode);
extern int nfs_wb_folio(struct inode *inode, struct folio *folio);
+extern int nfs_wb_folio_reclaim(struct inode *inode, struct folio *folio);
int nfs_wb_folio_cancel(struct inode *inode, struct folio *folio);
extern int nfs_commit_inode(struct inode *, int);
extern struct nfs_commit_data *nfs_commitdata_alloc(void);
Patches currently in stable-queue which might be from 1468888505@139.com are
queue-6.6/pnfs-fix-a-deadlock-when-returning-a-delegation-during-open.patch
queue-6.6/nfs-pass-explicit-offset-count-to-trace-events.patch
queue-6.6/nfs-fix-a-deadlock-involving-nfs_release_folio.patch
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2026-02-24 7:02 [PATCH 6.6.y 2/2] NFS: Fix a deadlock involving nfs_release_folio() Li hongliang
2026-03-19 11:12 ` Patch "NFS: Fix a deadlock involving nfs_release_folio()" has been added to the 6.6-stable tree gregkh
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