6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chao Yu chao@kernel.org
[ Upstream commit f10a890308a7cd8794e21f646f09827c6cb4bf5d ]
syzbot reports deadlock issue of f2fs as below:
====================================================== WARNING: possible circular locking dependency detected 6.12.0-rc3-syzkaller-00087-gc964ced77262 #0 Not tainted ------------------------------------------------------ kswapd0/79 is trying to acquire lock: ffff888011824088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2199 [inline] ffff888011824088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_record_stop_reason+0x52/0x1d0 fs/f2fs/super.c:4068
but task is already holding lock: ffff88804bd92610 (sb_internal#2){.+.+}-{0:0}, at: f2fs_evict_inode+0x662/0x15c0 fs/f2fs/inode.c:842
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (sb_internal#2){.+.+}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1716 [inline] sb_start_intwrite+0x4d/0x1c0 include/linux/fs.h:1899 f2fs_evict_inode+0x662/0x15c0 fs/f2fs/inode.c:842 evict+0x4e8/0x9b0 fs/inode.c:725 f2fs_evict_inode+0x1a4/0x15c0 fs/f2fs/inode.c:807 evict+0x4e8/0x9b0 fs/inode.c:725 dispose_list fs/inode.c:774 [inline] prune_icache_sb+0x239/0x2f0 fs/inode.c:963 super_cache_scan+0x38c/0x4b0 fs/super.c:223 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3799/0x3de0 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1ca3/0x3700 mm/vmscan.c:7226 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
-> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:3834 [inline] fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3848 might_alloc include/linux/sched/mm.h:318 [inline] prepare_alloc_pages+0x147/0x5b0 mm/page_alloc.c:4493 __alloc_pages_noprof+0x16f/0x710 mm/page_alloc.c:4722 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265 alloc_pages_noprof mm/mempolicy.c:2345 [inline] folio_alloc_noprof+0x128/0x180 mm/mempolicy.c:2352 filemap_alloc_folio_noprof+0xdf/0x500 mm/filemap.c:1010 do_read_cache_folio+0x2eb/0x850 mm/filemap.c:3787 read_mapping_folio include/linux/pagemap.h:1011 [inline] f2fs_commit_super+0x3c0/0x7d0 fs/f2fs/super.c:4032 f2fs_record_stop_reason+0x13b/0x1d0 fs/f2fs/super.c:4079 f2fs_handle_critical_error+0x2ac/0x5c0 fs/f2fs/super.c:4174 f2fs_write_inode+0x35f/0x4d0 fs/f2fs/inode.c:785 write_inode fs/fs-writeback.c:1503 [inline] __writeback_single_inode+0x711/0x10d0 fs/fs-writeback.c:1723 writeback_single_inode+0x1f3/0x660 fs/fs-writeback.c:1779 sync_inode_metadata+0xc4/0x120 fs/fs-writeback.c:2849 f2fs_release_file+0xa8/0x100 fs/f2fs/file.c:1941 __fput+0x23f/0x880 fs/file_table.c:431 task_work_run+0x24f/0x310 kernel/task_work.c:228 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (&sbi->sb_lock){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 down_write+0x99/0x220 kernel/locking/rwsem.c:1577 f2fs_down_write fs/f2fs/f2fs.h:2199 [inline] f2fs_record_stop_reason+0x52/0x1d0 fs/f2fs/super.c:4068 f2fs_handle_critical_error+0x2ac/0x5c0 fs/f2fs/super.c:4174 f2fs_evict_inode+0xa61/0x15c0 fs/f2fs/inode.c:883 evict+0x4e8/0x9b0 fs/inode.c:725 f2fs_evict_inode+0x1a4/0x15c0 fs/f2fs/inode.c:807 evict+0x4e8/0x9b0 fs/inode.c:725 dispose_list fs/inode.c:774 [inline] prune_icache_sb+0x239/0x2f0 fs/inode.c:963 super_cache_scan+0x38c/0x4b0 fs/super.c:223 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3799/0x3de0 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1ca3/0x3700 mm/vmscan.c:7226 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
other info that might help us debug this:
Chain exists of: &sbi->sb_lock --> fs_reclaim --> sb_internal#2
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- rlock(sb_internal#2); lock(fs_reclaim); lock(sb_internal#2); lock(&sbi->sb_lock);
Root cause is there will be potential deadlock in between below tasks:
Thread A Kswapd - f2fs_ioc_commit_atomic_write - mnt_want_write_file -- down_read lock A - balance_pgdat - __fs_reclaim_acquire -- lock B - shrink_node - prune_icache_sb - dispose_list - f2fs_evict_inode - sb_start_intwrite -- down_read lock A - f2fs_do_sync_file - f2fs_write_inode - f2fs_handle_critical_error - f2fs_record_stop_reason - f2fs_commit_super - read_mapping_folio - filemap_alloc_folio_noprof - fs_reclaim_acquire -- lock B
Both threads try to acquire read lock of lock A, then its upcoming write lock grabber will trigger deadlock.
Let's always create an asynchronous task in f2fs_handle_critical_error() rather than calling f2fs_record_stop_reason() synchronously to avoid this potential deadlock issue.
Fixes: b62e71be2110 ("f2fs: support errors=remount-ro|continue|panic mountoption") Reported-by: syzbot+be4a9983e95a5e25c8d3@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6704d667.050a0220.1e4d62.0081.GAE@google.com Signed-off-by: Chao Yu chao@kernel.org Reviewed-by: Daejun Park daejun7.park@samsung.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/checkpoint.c | 2 +- fs/f2fs/f2fs.h | 3 +-- fs/f2fs/super.c | 13 +++++++------ 3 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c index 1a33a8c1623f2..c6317596e695c 100644 --- a/fs/f2fs/checkpoint.c +++ b/fs/f2fs/checkpoint.c @@ -32,7 +32,7 @@ void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi, bool end_io, f2fs_build_fault_attr(sbi, 0, 0); if (!end_io) f2fs_flush_merged_writes(sbi); - f2fs_handle_critical_error(sbi, reason, end_io); + f2fs_handle_critical_error(sbi, reason); }
/* diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 7faf9446ea5dc..33620642ae5ec 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3588,8 +3588,7 @@ int f2fs_quota_sync(struct super_block *sb, int type); loff_t max_file_blocks(struct inode *inode); void f2fs_quota_off_umount(struct super_block *sb); void f2fs_save_errors(struct f2fs_sb_info *sbi, unsigned char flag); -void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason, - bool irq_context); +void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason); void f2fs_handle_error(struct f2fs_sb_info *sbi, unsigned char error); void f2fs_handle_error_async(struct f2fs_sb_info *sbi, unsigned char error); int f2fs_commit_super(struct f2fs_sb_info *sbi, bool recover); diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 540fa1dfc77df..f05d0e43db9e2 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -4093,8 +4093,7 @@ static bool system_going_down(void) || system_state == SYSTEM_RESTART; }
-void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason, - bool irq_context) +void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason) { struct super_block *sb = sbi->sb; bool shutdown = reason == STOP_CP_REASON_SHUTDOWN; @@ -4106,10 +4105,12 @@ void f2fs_handle_critical_error(struct f2fs_sb_info *sbi, unsigned char reason, if (!f2fs_hw_is_readonly(sbi)) { save_stop_reason(sbi, reason);
- if (irq_context && !shutdown) - schedule_work(&sbi->s_error_work); - else - f2fs_record_stop_reason(sbi); + /* + * always create an asynchronous task to record stop_reason + * in order to avoid potential deadlock when running into + * f2fs_record_stop_reason() synchronously. + */ + schedule_work(&sbi->s_error_work); }
/*