From 1c0e68339c9012ecf4251806906ce63401d02691 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Wed, 27 Oct 2021 09:07:09 -0700 Subject: [PATCH] ANDROID: f2fs: fix potential deadlock by android ftrace sb_internal#2 --> &s->s_dquot.dqio_sem --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&s->s_dquot.dqio_sem); lock(fs_reclaim); lock(sb_internal#2); *** DEADLOCK *** 3 locks held by kswapd0/133: #0: ffffffda597c93a8 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x4/0x50 #1: ffffffda597bc890 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0xa0/0x19c #2: ffffff80d5fb90e0 (&type->s_umount_key#50){.+.+}-{3:3}, at: super_cache_scan+0x40/0x1dc stack backtrace: CPU: 7 PID: 133 Comm: kswapd0 Tainted: G W O 5.10.43-android12-9-g4665ec64f3df #1 Hardware name: MT6879(ENG) (DT) Call trace: dump_backtrace.cfi_jt+0x0/0x8 show_stack+0x1c/0x2c dump_stack_lvl+0xd8/0x16c print_circular_bug+0x2d4/0x2d8 check_noncircular+0x190/0x1a4 validate_chain+0xc54/0x2d34 __lock_acquire+0x7e4/0xed4 lock_acquire+0x114/0x394 f2fs_evict_inode+0x1a0/0x8b8 evict+0xd4/0x2f8 iput+0x1c0/0x258 dentry_unlink_inode+0x16c/0x1dc __dentry_kill+0x128/0x280 shrink_dentry_list+0x6c/0x420 prune_dcache_sb+0x5c/0x90 super_cache_scan+0x13c/0x1dc do_shrink_slab+0x1e0/0x388 shrink_slab+0xf4/0x19c shrink_node_memcgs+0x80/0x25c shrink_node+0x324/0x710 balance_pgdat+0x3a8/0x6a8 kswapd+0x484/0x594 kthread+0x15c/0x1ac ret_from_fork+0x10/0x30 Bug: 201025620 Signed-off-by: Jaegeuk Kim Change-Id: Idaa303eb7c681a56ad5d4e1f6dddbda71f7fece4 --- fs/f2fs/data.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 821da92fe5c2..4a986daad16b 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -3314,7 +3314,13 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping, block_t blkaddr = NULL_ADDR; int err = 0; - if (trace_android_fs_datawrite_start_enabled()) { + /* + * Should avoid quota operations which can make deadlock: + * kswapd -> f2fs_evict_inode -> dquot_drop -> + * f2fs_dquot_commit -> f2fs_write_begin -> + * d_obtain_alias -> __d_alloc -> kmem_cache_alloc(GFP_KERNEL) + */ + if (trace_android_fs_datawrite_start_enabled() && !IS_NOQUOTA(inode)) { char *path, pathbuf[MAX_TRACE_PATHBUF_LEN]; path = android_fstrace_get_pathname(pathbuf,