From: Chao Yu Date: Wed, 20 May 2026 11:17:33 +0000 (-0400) Subject: f2fs: fix false alarm of lockdep on cp_global_sem lock X-Git-Tag: v6.6.141~14 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8358a142f2a1876f929ef1da25c0cedaf59b4caa;p=thirdparty%2Fkernel%2Fstable.git f2fs: fix false alarm of lockdep on cp_global_sem lock [ Upstream commit 6a5e3de9c2bb0b691d16789a5d19e9276a09b308 ] lockdep reported a potential deadlock: a) TCMU device removal context: - call del_gendisk() to get q->q_usage_counter - call start_flush_work() to get work_completion of wb->dwork b) f2fs writeback context: - in wb_workfn(), which holds work_completion of wb->dwork - call f2fs_balance_fs() to get sbi->gc_lock c) f2fs vfs_write context: - call f2fs_gc() to get sbi->gc_lock - call f2fs_write_checkpoint() to get sbi->cp_global_sem d) f2fs mount context: - call recover_fsync_data() to get sbi->cp_global_sem - call f2fs_check_and_fix_write_pointer() to call blkdev_report_zones() that goes down to blk_mq_alloc_request and get q->q_usage_counter Original callstack is in Closes tag. However, I think this is a false alarm due to before mount returns successfully (context d), we can not access file therein via vfs_write (context c). Let's introduce per-sb cp_global_sem_key, and assign the key for cp_global_sem, so that lockdep can recognize cp_global_sem from different super block correctly. A lot of work are done by Shin'ichiro Kawasaki, thanks a lot for the work. Fixes: c426d99127b1 ("f2fs: Check write pointer consistency of open zones") Cc: stable@kernel.org Reported-and-tested-by: Shin'ichiro Kawasaki Closes: https://lore.kernel.org/linux-f2fs-devel/20260218125237.3340441-1-shinichiro.kawasaki@wdc.com Signed-off-by: Shin'ichiro Kawasaki Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ re-anchored lockdep_register_key after init_f2fs_rwsem and placed lockdep_unregister_key before kfree(sbi) in f2fs_put_super instead of kill_f2fs_super ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index fb35f78e60bb3..50847fd7e5504 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1824,6 +1824,9 @@ struct f2fs_sb_info { spinlock_t iostat_lat_lock; struct iostat_lat_info *iostat_io_lat; #endif +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lock_class_key cp_global_sem_key; +#endif }; /* Definitions to access f2fs_sb_info */ diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 7614d93bd67fb..c018d548e1634 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -1694,6 +1694,9 @@ static void f2fs_put_super(struct super_block *sb) kvfree(sbi->write_io[i]); #if IS_ENABLED(CONFIG_UNICODE) utf8_unload(sb->s_encoding); +#endif +#ifdef CONFIG_DEBUG_LOCK_ALLOC + lockdep_unregister_key(&sbi->cp_global_sem_key); #endif kfree(sbi); } @@ -4380,6 +4383,11 @@ try_onemore: init_f2fs_rwsem(&sbi->gc_lock); mutex_init(&sbi->writepages); init_f2fs_rwsem(&sbi->cp_global_sem); +#ifdef CONFIG_DEBUG_LOCK_ALLOC + lockdep_register_key(&sbi->cp_global_sem_key); + lockdep_set_class(&sbi->cp_global_sem.internal_rwsem, + &sbi->cp_global_sem_key); +#endif init_f2fs_rwsem(&sbi->node_write); init_f2fs_rwsem(&sbi->node_change); spin_lock_init(&sbi->stat_lock); @@ -4838,6 +4846,9 @@ free_sb_buf: free_sbi: if (sbi->s_chksum_driver) crypto_free_shash(sbi->s_chksum_driver); +#ifdef CONFIG_DEBUG_LOCK_ALLOC + lockdep_unregister_key(&sbi->cp_global_sem_key); +#endif kfree(sbi); /* give only one another chance */