FAILED: patch "[PATCH] fs: quota: create dedicated workqueue for quota_release_work" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] fs: quota: create dedicated workqueue for quota_release_work" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 72b7ceca857f38a8ca7c5629feffc63769638974
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025101650-tighten-fleshed-6fe0@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 72b7ceca857f38a8ca7c5629feffc63769638974 Mon Sep 17 00:00:00 2001
From: Shashank A P <shashank.ap@samsung.com>
Date: Mon, 1 Sep 2025 14:59:00 +0530
Subject: [PATCH] fs: quota: create dedicated workqueue for quota_release_work

There is a kernel panic due to WARN_ONCE when panic_on_warn is set.

This issue occurs when writeback is triggered due to sync call for an
opened file(ie, writeback reason is WB_REASON_SYNC). When f2fs balance
is needed at sync path, flush for quota_release_work is triggered.
By default quota_release_work is queued to "events_unbound" queue which
does not have WQ_MEM_RECLAIM flag. During f2fs balance "writeback"
workqueue tries to flush quota_release_work causing kernel panic due to
MEM_RECLAIM flag mismatch errors.

This patch creates dedicated workqueue with WQ_MEM_RECLAIM flag
for work quota_release_work.

------------[ cut here ]------------
WARNING: CPU: 4 PID: 14867 at kernel/workqueue.c:3721 check_flush_dependency+0x13c/0x148
Call trace:
 check_flush_dependency+0x13c/0x148
 __flush_work+0xd0/0x398
 flush_delayed_work+0x44/0x5c
 dquot_writeback_dquots+0x54/0x318
 f2fs_do_quota_sync+0xb8/0x1a8
 f2fs_write_checkpoint+0x3cc/0x99c
 f2fs_gc+0x190/0x750
 f2fs_balance_fs+0x110/0x168
 f2fs_write_single_data_page+0x474/0x7dc
 f2fs_write_data_pages+0x7d0/0xd0c
 do_writepages+0xe0/0x2f4
 __writeback_single_inode+0x44/0x4ac
 writeback_sb_inodes+0x30c/0x538
 wb_writeback+0xf4/0x440
 wb_workfn+0x128/0x5d4
 process_scheduled_works+0x1c4/0x45c
 worker_thread+0x32c/0x3e8
 kthread+0x11c/0x1b0
 ret_from_fork+0x10/0x20
Kernel panic - not syncing: kernel: panic_on_warn set ...

Fixes: ac6f420291b3 ("quota: flush quota_release_work upon quota writeback")
CC: stable@vger.kernel.org
Signed-off-by: Shashank A P <shashank.ap@samsung.com>
Link: https://patch.msgid.link/20250901092905.2115-1-shashank.ap@samsung.com
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index df4a9b348769..6c4a6ee1fa2b 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -162,6 +162,9 @@ static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;
 /* SLAB cache for dquot structures */
 static struct kmem_cache *dquot_cachep;
 
+/* workqueue for work quota_release_work*/
+static struct workqueue_struct *quota_unbound_wq;
+
 void register_quota_format(struct quota_format_type *fmt)
 {
 	spin_lock(&dq_list_lock);
@@ -881,7 +884,7 @@ void dqput(struct dquot *dquot)
 	put_releasing_dquots(dquot);
 	atomic_dec(&dquot->dq_count);
 	spin_unlock(&dq_list_lock);
-	queue_delayed_work(system_unbound_wq, &quota_release_work, 1);
+	queue_delayed_work(quota_unbound_wq, &quota_release_work, 1);
 }
 EXPORT_SYMBOL(dqput);
 
@@ -3041,6 +3044,11 @@ static int __init dquot_init(void)
 
 	shrinker_register(dqcache_shrinker);
 
+	quota_unbound_wq = alloc_workqueue("quota_events_unbound",
+					   WQ_UNBOUND | WQ_MEM_RECLAIM, WQ_MAX_ACTIVE);
+	if (!quota_unbound_wq)
+		panic("Cannot create quota_unbound_wq\n");
+
 	return 0;
 }
 fs_initcall(dquot_init);

[PATCH 6.6.y 1/2] quota: remove unneeded return value of register_quota_format

[Sasha Levin]

From: Kemeng Shi <shikemeng@huaweicloud.com>

[ Upstream commit a838e5dca63d1dc701e63b2b1176943c57485c45 ]

The register_quota_format always returns 0, simply remove unneeded return
value.

Link: https://patch.msgid.link/20240715130534.2112678-3-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Stable-dep-of: 72b7ceca857f ("fs: quota: create dedicated workqueue for quota_release_work")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ocfs2/super.c      | 6 ++----
 fs/quota/dquot.c      | 3 +--
 fs/quota/quota_v1.c   | 3 ++-
 fs/quota/quota_v2.c   | 9 +++------
 include/linux/quota.h | 2 +-
 mm/shmem.c            | 7 +------
 6 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index e585e77cdc88e..18dba873a1633 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1571,15 +1571,13 @@ static int __init ocfs2_init(void)
 
 	ocfs2_set_locking_protocol();
 
-	status = register_quota_format(&ocfs2_quota_format);
-	if (status < 0)
-		goto out3;
+	register_quota_format(&ocfs2_quota_format);
+
 	status = register_filesystem(&ocfs2_fs_type);
 	if (!status)
 		return 0;
 
 	unregister_quota_format(&ocfs2_quota_format);
-out3:
 	debugfs_remove(ocfs2_debugfs_root);
 	ocfs2_free_mem_caches();
 out2:
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 67562c78e57d5..ba227502b03d7 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -163,13 +163,12 @@ static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;
 /* SLAB cache for dquot structures */
 static struct kmem_cache *dquot_cachep;
 
-int register_quota_format(struct quota_format_type *fmt)
+void register_quota_format(struct quota_format_type *fmt)
 {
 	spin_lock(&dq_list_lock);
 	fmt->qf_next = quota_formats;
 	quota_formats = fmt;
 	spin_unlock(&dq_list_lock);
-	return 0;
 }
 EXPORT_SYMBOL(register_quota_format);
 
diff --git a/fs/quota/quota_v1.c b/fs/quota/quota_v1.c
index a0db3f195e951..8aaf4a501fc0d 100644
--- a/fs/quota/quota_v1.c
+++ b/fs/quota/quota_v1.c
@@ -229,7 +229,8 @@ static struct quota_format_type v1_quota_format = {
 
 static int __init init_v1_quota_format(void)
 {
-        return register_quota_format(&v1_quota_format);
+	register_quota_format(&v1_quota_format);
+	return 0;
 }
 
 static void __exit exit_v1_quota_format(void)
diff --git a/fs/quota/quota_v2.c b/fs/quota/quota_v2.c
index 7978ab671e0c6..d73f443292771 100644
--- a/fs/quota/quota_v2.c
+++ b/fs/quota/quota_v2.c
@@ -422,12 +422,9 @@ static struct quota_format_type v2r1_quota_format = {
 
 static int __init init_v2_quota_format(void)
 {
-	int ret;
-
-	ret = register_quota_format(&v2r0_quota_format);
-	if (ret)
-		return ret;
-	return register_quota_format(&v2r1_quota_format);
+	register_quota_format(&v2r0_quota_format);
+	register_quota_format(&v2r1_quota_format);
+	return 0;
 }
 
 static void __exit exit_v2_quota_format(void)
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 07071e64abf3d..89a0d83ddad08 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -526,7 +526,7 @@ struct quota_info {
 	const struct quota_format_ops *ops[MAXQUOTAS];	/* Operations for each type */
 };
 
-int register_quota_format(struct quota_format_type *fmt);
+void register_quota_format(struct quota_format_type *fmt);
 void unregister_quota_format(struct quota_format_type *fmt);
 
 struct quota_module_name {
diff --git a/mm/shmem.c b/mm/shmem.c
index ecf1011cc3e29..2260def68090c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4617,11 +4617,7 @@ void __init shmem_init(void)
 	shmem_init_inodecache();
 
 #ifdef CONFIG_TMPFS_QUOTA
-	error = register_quota_format(&shmem_quota_format);
-	if (error < 0) {
-		pr_err("Could not register quota format\n");
-		goto out3;
-	}
+	register_quota_format(&shmem_quota_format);
 #endif
 
 	error = register_filesystem(&shmem_fs_type);
@@ -4650,7 +4646,6 @@ void __init shmem_init(void)
 out2:
 #ifdef CONFIG_TMPFS_QUOTA
 	unregister_quota_format(&shmem_quota_format);
-out3:
 #endif
 	shmem_destroy_inodecache();
 	shm_mnt = ERR_PTR(error);
-- 
2.51.0

[PATCH 6.6.y 2/2] fs: quota: create dedicated workqueue for quota_release_work

[Sasha Levin]

From: Shashank A P <shashank.ap@samsung.com>

[ Upstream commit 72b7ceca857f38a8ca7c5629feffc63769638974 ]

There is a kernel panic due to WARN_ONCE when panic_on_warn is set.

This issue occurs when writeback is triggered due to sync call for an
opened file(ie, writeback reason is WB_REASON_SYNC). When f2fs balance
is needed at sync path, flush for quota_release_work is triggered.
By default quota_release_work is queued to "events_unbound" queue which
does not have WQ_MEM_RECLAIM flag. During f2fs balance "writeback"
workqueue tries to flush quota_release_work causing kernel panic due to
MEM_RECLAIM flag mismatch errors.

This patch creates dedicated workqueue with WQ_MEM_RECLAIM flag
for work quota_release_work.

------------[ cut here ]------------
WARNING: CPU: 4 PID: 14867 at kernel/workqueue.c:3721 check_flush_dependency+0x13c/0x148
Call trace:
 check_flush_dependency+0x13c/0x148
 __flush_work+0xd0/0x398
 flush_delayed_work+0x44/0x5c
 dquot_writeback_dquots+0x54/0x318
 f2fs_do_quota_sync+0xb8/0x1a8
 f2fs_write_checkpoint+0x3cc/0x99c
 f2fs_gc+0x190/0x750
 f2fs_balance_fs+0x110/0x168
 f2fs_write_single_data_page+0x474/0x7dc
 f2fs_write_data_pages+0x7d0/0xd0c
 do_writepages+0xe0/0x2f4
 __writeback_single_inode+0x44/0x4ac
 writeback_sb_inodes+0x30c/0x538
 wb_writeback+0xf4/0x440
 wb_workfn+0x128/0x5d4
 process_scheduled_works+0x1c4/0x45c
 worker_thread+0x32c/0x3e8
 kthread+0x11c/0x1b0
 ret_from_fork+0x10/0x20
Kernel panic - not syncing: kernel: panic_on_warn set ...

Fixes: ac6f420291b3 ("quota: flush quota_release_work upon quota writeback")
CC: stable@vger.kernel.org
Signed-off-by: Shashank A P <shashank.ap@samsung.com>
Link: https://patch.msgid.link/20250901092905.2115-1-shashank.ap@samsung.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/quota/dquot.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index ba227502b03d7..42a7d0a71b22e 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -163,6 +163,9 @@ static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;
 /* SLAB cache for dquot structures */
 static struct kmem_cache *dquot_cachep;
 
+/* workqueue for work quota_release_work*/
+static struct workqueue_struct *quota_unbound_wq;
+
 void register_quota_format(struct quota_format_type *fmt)
 {
 	spin_lock(&dq_list_lock);
@@ -891,7 +894,7 @@ void dqput(struct dquot *dquot)
 	put_releasing_dquots(dquot);
 	atomic_dec(&dquot->dq_count);
 	spin_unlock(&dq_list_lock);
-	queue_delayed_work(system_unbound_wq, &quota_release_work, 1);
+	queue_delayed_work(quota_unbound_wq, &quota_release_work, 1);
 }
 EXPORT_SYMBOL(dqput);
 
@@ -3046,6 +3049,11 @@ static int __init dquot_init(void)
 	if (register_shrinker(&dqcache_shrinker, "dquota-cache"))
 		panic("Cannot register dquot shrinker");
 
+	quota_unbound_wq = alloc_workqueue("quota_events_unbound",
+					   WQ_UNBOUND | WQ_MEM_RECLAIM, WQ_MAX_ACTIVE);
+	if (!quota_unbound_wq)
+		panic("Cannot create quota_unbound_wq\n");
+
 	return 0;
 }
 fs_initcall(dquot_init);
-- 
2.51.0