linux/fs/f2fs
Chao Yu 040d2bb318 f2fs: fix to avoid deadloop if data_flush is on
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>
2019-05-23 07:03:19 -07:00
..
acl.c f2fs: Replace spaces with tab 2019-05-08 21:23:11 -07:00
acl.h f2fs: add SPDX license identifiers 2018-09-12 13:07:10 -07:00
checkpoint.c f2fs: fix to check layout on last valid checkpoint park 2019-05-23 07:03:18 -07:00
data.c f2fs: fix to avoid deadloop if data_flush is on 2019-05-23 07:03:19 -07:00
debug.c f2fs: no need to check return value of debugfs_create functions 2019-01-22 14:25:25 +01:00
dir.c f2fs-for-5.1-rc1 2019-03-15 13:42:53 -07:00
extent_cache.c f2fs: fix to initialize variable to avoid UBSAN/smatch warning 2019-01-22 15:31:26 -08:00
f2fs.h f2fs: fix to avoid deadloop if data_flush is on 2019-05-23 07:03:19 -07:00
file.c f2fs: add tracepoint for f2fs_filemap_fault() 2019-05-08 21:23:13 -07:00
gc.c f2fs: allow ssr block allocation during checkpoint=disable period 2019-05-23 07:03:18 -07:00
gc.h f2fs: add SPDX license identifiers 2018-09-12 13:07:10 -07:00
hash.c f2fs: add SPDX license identifiers 2018-09-12 13:07:10 -07:00
inline.c f2fs: fix to retrieve inline xattr space 2019-05-08 21:23:06 -07:00
inode.c f2fs: introduce DATA_GENERIC_ENHANCE 2019-05-08 21:23:13 -07:00
Kconfig fscrypt: remove filesystem specific build config option 2019-01-23 23:56:43 -05:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
namei.c f2fs-for-5.2-rc1 2019-05-14 08:55:43 -07:00
node.c f2fs-for-5.2-rc1 2019-05-14 08:55:43 -07:00
node.h f2fs: check PageWriteback flag for ordered case 2018-12-26 15:16:56 -08:00
recovery.c f2fs: introduce DATA_GENERIC_ENHANCE 2019-05-08 21:23:13 -07:00
segment.c f2fs: fix to avoid deadloop if data_flush is on 2019-05-23 07:03:19 -07:00
segment.h f2fs: introduce DATA_GENERIC_ENHANCE 2019-05-08 21:23:13 -07:00
shrinker.c f2fs: fix sbi->extent_list corruption issue 2018-12-26 15:16:54 -08:00
super.c f2fs: fix to avoid deadloop if data_flush is on 2019-05-23 07:03:19 -07:00
sysfs.c f2fs-for-5.1-rc1 2019-03-15 13:42:53 -07:00
trace.c f2fs: do not use mutex lock in atomic context 2019-03-05 19:58:06 -08:00
trace.h f2fs: add SPDX license identifiers 2018-09-12 13:07:10 -07:00
xattr.c f2fs: fix to avoid accessing xattr across the boundary 2019-05-09 09:43:29 -07:00
xattr.h f2fs: fix to avoid accessing xattr across the boundary 2019-05-09 09:43:29 -07:00