From: Chao Yu yuchao0@huawei.com
[ Upstream commit 040d2bb318d1aea4f28cc22504b44e446666c86e ]
As Hagbard Celine reported:
[ 615.697824] INFO: task kworker/u16:5:344 blocked for more than 120 seconds. [ 615.697825] Not tainted 5.0.15-gentoo-f2fslog #4 [ 615.697826] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 615.697827] kworker/u16:5 D 0 344 2 0x80000000 [ 615.697831] Workqueue: writeback wb_workfn (flush-259:0) [ 615.697832] Call Trace: [ 615.697836] ? __schedule+0x2c5/0x8b0 [ 615.697839] schedule+0x32/0x80 [ 615.697841] schedule_preempt_disabled+0x14/0x20 [ 615.697842] __mutex_lock.isra.8+0x2ba/0x4d0 [ 615.697845] ? log_store+0xf5/0x260 [ 615.697848] f2fs_write_data_pages+0x133/0x320 [ 615.697851] ? trace_hardirqs_on+0x2c/0xe0 [ 615.697854] do_writepages+0x41/0xd0 [ 615.697857] __filemap_fdatawrite_range+0x81/0xb0 [ 615.697859] f2fs_sync_dirty_inodes+0x1dd/0x200 [ 615.697861] f2fs_balance_fs_bg+0x2a7/0x2c0 [ 615.697863] ? up_read+0x5/0x20 [ 615.697865] ? f2fs_do_write_data_page+0x2cb/0x940 [ 615.697867] f2fs_balance_fs+0xe5/0x2c0 [ 615.697869] __write_data_page+0x1c8/0x6e0 [ 615.697873] f2fs_write_cache_pages+0x1e0/0x450 [ 615.697878] f2fs_write_data_pages+0x14b/0x320 [ 615.697880] ? trace_hardirqs_on+0x2c/0xe0 [ 615.697883] do_writepages+0x41/0xd0 [ 615.697885] __filemap_fdatawrite_range+0x81/0xb0 [ 615.697887] f2fs_sync_dirty_inodes+0x1dd/0x200 [ 615.697889] f2fs_balance_fs_bg+0x2a7/0x2c0 [ 615.697891] f2fs_write_node_pages+0x51/0x220 [ 615.697894] do_writepages+0x41/0xd0 [ 615.697897] __writeback_single_inode+0x3d/0x3d0 [ 615.697899] writeback_sb_inodes+0x1e8/0x410 [ 615.697902] __writeback_inodes_wb+0x5d/0xb0 [ 615.697904] wb_writeback+0x28f/0x340 [ 615.697906] ? cpumask_next+0x16/0x20 [ 615.697908] wb_workfn+0x33e/0x420 [ 615.697911] process_one_work+0x1a1/0x3d0 [ 615.697913] worker_thread+0x30/0x380 [ 615.697915] ? process_one_work+0x3d0/0x3d0 [ 615.697916] kthread+0x116/0x130 [ 615.697918] ? kthread_create_worker_on_cpu+0x70/0x70 [ 615.697921] ret_from_fork+0x3a/0x50
There is still deadloop in below condition:
d A - do_writepages - f2fs_write_node_pages - f2fs_balance_fs_bg - f2fs_sync_dirty_inodes - f2fs_write_cache_pages - mutex_lock(&sbi->writepages) -- lock once - __write_data_page - f2fs_balance_fs_bg - f2fs_sync_dirty_inodes - f2fs_write_data_pages - mutex_lock(&sbi->writepages) -- lock again
Thread A Thread B - do_writepages - f2fs_write_node_pages - f2fs_balance_fs_bg - f2fs_sync_dirty_inodes - .cp_task = current - f2fs_sync_dirty_inodes - .cp_task = current - filemap_fdatawrite - .cp_task = NULL - filemap_fdatawrite - f2fs_write_cache_pages - enter f2fs_balance_fs_bg since .cp_task is NULL - .cp_task = NULL
Change as below to avoid this: - add condition to avoid holding .writepages mutex lock in path of data flush - introduce mutex lock sbi.flush_lock to exclude concurrent data flush in background.
Signed-off-by: Chao Yu yuchao0@huawei.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/data.c | 3 +++ fs/f2fs/f2fs.h | 1 + fs/f2fs/segment.c | 4 ++++ fs/f2fs/super.c | 1 + 4 files changed, 9 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index eda4181d2092..923923603a7d 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2262,6 +2262,9 @@ static inline bool __should_serialize_io(struct inode *inode, return false; if (IS_NOQUOTA(inode)) return false; + /* to avoid deadlock in path of data flush */ + if (F2FS_I(inode)->cp_task) + return false; if (wbc->sync_mode != WB_SYNC_ALL) return true; if (get_dirty_pages(inode) >= SM_I(F2FS_I_SB(inode))->min_seq_blocks) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 06b89a9862ab..d1b64cb77326 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1207,6 +1207,7 @@ struct f2fs_sb_info { /* for inode management */ struct list_head inode_list[NR_INODE_TYPE]; /* dirty inode list */ spinlock_t inode_lock[NR_INODE_TYPE]; /* for dirty inode list lock */ + struct mutex flush_lock; /* for flush exclusion */
/* for extent tree cache */ struct radix_tree_root extent_tree_root;/* cache extent cache entries */ diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 8dee063c833f..a96b9e964733 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -546,9 +546,13 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi) if (test_opt(sbi, DATA_FLUSH)) { struct blk_plug plug;
+ mutex_lock(&sbi->flush_lock); + blk_start_plug(&plug); f2fs_sync_dirty_inodes(sbi, FILE_INODE); blk_finish_plug(&plug); + + mutex_unlock(&sbi->flush_lock); } f2fs_sync_fs(sbi->sb, true); stat_inc_bg_cp_count(sbi->stat_info); diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 856f9081c599..4b47ac994daf 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3296,6 +3296,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) INIT_LIST_HEAD(&sbi->inode_list[i]); spin_lock_init(&sbi->inode_lock[i]); } + mutex_init(&sbi->flush_lock);
f2fs_init_extent_cache_info(sbi);