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| author | Zhihao Cheng <chengzhihao1@huawei.com> | 2021-12-27 06:22:33 +0300 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2022-01-09 23:33:25 +0300 |
| commit | afd427048047e8efdedab30e8888044e2be5aa9c (patch) | |
| tree | 15ff09683065abc23e7ce6a240432cfc1c556eb7 /fs/ubifs/lpt_commit.c | |
| parent | 40a8f0d5e7b3999f096570edab71c345da812e3e (diff) | |
| download | linux-afd427048047e8efdedab30e8888044e2be5aa9c.tar.xz | |
ubifs: Fix deadlock in concurrent rename whiteout and inode writeback
Following hung tasks:
[ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132
[ 77.028820] Call Trace:
[ 77.029027] schedule+0x8c/0x1b0
[ 77.029067] mutex_lock+0x50/0x60
[ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs]
[ 77.029117] __writeback_single_inode+0x43c/0x570
[ 77.029128] writeback_sb_inodes+0x259/0x740
[ 77.029148] wb_writeback+0x107/0x4d0
[ 77.029163] wb_workfn+0x162/0x7b0
[ 92.390442] task:aa state:D stack: 0 pid: 1506
[ 92.390448] Call Trace:
[ 92.390458] schedule+0x8c/0x1b0
[ 92.390461] wb_wait_for_completion+0x82/0xd0
[ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110
[ 92.390472] writeback_inodes_sb_nr+0x14/0x20
[ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs]
[ 92.390503] do_rename.cold+0x7f/0x187 [ubifs]
[ 92.390549] ubifs_rename+0x8b/0x180 [ubifs]
[ 92.390571] vfs_rename+0xdb2/0x1170
[ 92.390580] do_renameat2+0x554/0x770
, are caused by concurrent rename whiteout and inode writeback processes:
rename_whiteout(Thread 1) wb_workfn(Thread2)
ubifs_rename
do_rename
lock_4_inodes (Hold ui_mutex)
ubifs_budget_space
make_free_space
shrink_liability
__writeback_inodes_sb_nr
bdi_split_work_to_wbs (Queue new wb work)
wb_do_writeback(wb work)
__writeback_single_inode
ubifs_write_inode
LOCK(ui_mutex)
↑
wb_wait_for_completion (Wait wb work) <-- deadlock!
Reproducer (Detail program in [Link]):
1. SYS_renameat2("/mp/dir/file", "/mp/dir/whiteout", RENAME_WHITEOUT)
2. Consume out of space before kernel(mdelay) doing budget for whiteout
Fix it by doing whiteout space budget before locking ubifs inodes.
BTW, it also fixes wrong goto tag 'out_release' in whiteout budget
error handling path(It should at least recover dir i_size and unlock
4 ubifs inodes).
Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214733
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'fs/ubifs/lpt_commit.c')
0 files changed, 0 insertions, 0 deletions