This is a note to let you know that I've just added the patch titled f2fs: Fix deadlock in f2fs_gc() context during atomic files handling to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: f2fs-fix-deadlock-in-f2fs_gc-context-during-atomic-f.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 13d4e15c39b4a40a1654752ae1d92a2521c3e6b9 Author: Sahitya Tummala <stummala@xxxxxxxxxxxxxx> Date: Wed Nov 13 16:01:03 2019 +0530 f2fs: Fix deadlock in f2fs_gc() context during atomic files handling [ Upstream commit 677017d196ba2a4cfff13626b951cc9a206b8c7c ] The FS got stuck in the below stack when the storage is almost full/dirty condition (when FG_GC is being done). schedule_timeout io_schedule_timeout congestion_wait f2fs_drop_inmem_pages_all f2fs_gc f2fs_balance_fs __write_node_page f2fs_fsync_node_pages f2fs_do_sync_file f2fs_ioctl The root cause for this issue is there is a potential infinite loop in f2fs_drop_inmem_pages_all() for the case where gc_failure is true and when there an inode whose i_gc_failures[GC_FAILURE_ATOMIC] is not set. Fix this by keeping track of the total atomic files currently opened and using that to exit from this condition. Fix-suggested-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index f078cd20dab8..9046432b87c2 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1289,6 +1289,7 @@ struct f2fs_sb_info { unsigned int gc_mode; /* current GC state */ unsigned int next_victim_seg[2]; /* next segment in victim section */ /* for skip statistic */ + unsigned int atomic_files; /* # of opened atomic file */ unsigned long long skipped_atomic_files[2]; /* FG_GC and BG_GC */ unsigned long long skipped_gc_rwsem; /* FG_GC only */ diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 29bc0a542759..8ed8e4328bd1 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1890,6 +1890,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) spin_lock(&sbi->inode_lock[ATOMIC_FILE]); if (list_empty(&fi->inmem_ilist)) list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]); + sbi->atomic_files++; spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); /* add inode in inmem_list first and set atomic_file */ diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 808709581481..7d8578401267 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -288,6 +288,8 @@ void f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure) struct list_head *head = &sbi->inode_list[ATOMIC_FILE]; struct inode *inode; struct f2fs_inode_info *fi; + unsigned int count = sbi->atomic_files; + unsigned int looped = 0; next: spin_lock(&sbi->inode_lock[ATOMIC_FILE]); if (list_empty(head)) { @@ -296,22 +298,26 @@ next: } fi = list_first_entry(head, struct f2fs_inode_info, inmem_ilist); inode = igrab(&fi->vfs_inode); + if (inode) + list_move_tail(&fi->inmem_ilist, head); spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); if (inode) { if (gc_failure) { - if (fi->i_gc_failures[GC_FAILURE_ATOMIC]) - goto drop; - goto skip; + if (!fi->i_gc_failures[GC_FAILURE_ATOMIC]) + goto skip; } -drop: set_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); f2fs_drop_inmem_pages(inode); +skip: iput(inode); } -skip: congestion_wait(BLK_RW_ASYNC, HZ/50); cond_resched(); + if (gc_failure) { + if (++looped >= count) + return; + } goto next; } @@ -327,13 +333,16 @@ void f2fs_drop_inmem_pages(struct inode *inode) mutex_unlock(&fi->inmem_lock); } - clear_inode_flag(inode, FI_ATOMIC_FILE); fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; stat_dec_atomic_write(inode); spin_lock(&sbi->inode_lock[ATOMIC_FILE]); if (!list_empty(&fi->inmem_ilist)) list_del_init(&fi->inmem_ilist); + if (f2fs_is_atomic_file(inode)) { + clear_inode_flag(inode, FI_ATOMIC_FILE); + sbi->atomic_files--; + } spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); }