6.6-stable review patch. If anyone has any objections, please let me know.
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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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/quota/dquot.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -163,6 +163,9 @@ static struct quota_module_name module_n /* 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, "a_release_work, 1); + queue_delayed_work(quota_unbound_wq, "a_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);