[PATCH] xfs: explicitly call cond_resched in xfs_itruncate_extents_flags

Jian Wen
2024-01-10T07:14:20Z

From: Jian Wen <wenjianhn@gmail.com>

Deleting a file with lots of extents may cause a soft lockup if the
preemption model is none(CONFIG_PREEMPT_NONE=y or preempt=none is set
in the kernel cmdline). Alibaba cloud kernel and Oracle UEK container
kernel are affected by the issue, since they select CONFIG_PREEMPT_NONE=y.

Explicitly call cond_resched in xfs_itruncate_extents_flags avoid
the below softlockup warning.
watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [kworker/0:13:139]
CPU: 0 PID: 139 Comm: kworker/0:13 Not tainted 6.7.0-rc8-g610a9b8f49fb #23
Workqueue: xfs-inodegc/vda1 xfs_inodegc_worker
Call Trace:
_raw_spin_lock+0x30/0x80
? xfs_extent_busy_trim+0x38/0x200
xfs_extent_busy_trim+0x38/0x200
xfs_alloc_compute_aligned+0x38/0xd0
xfs_alloc_ag_vextent_size+0x1f1/0x870
xfs_alloc_fix_freelist+0x58a/0x770
xfs_free_extent_fix_freelist+0x60/0xa0
__xfs_free_extent+0x66/0x1d0
xfs_trans_free_extent+0xac/0x290
xfs_extent_free_finish_item+0xf/0x40
xfs_defer_finish_noroll+0x1db/0x7f0
xfs_defer_finish+0x10/0xa0
xfs_itruncate_extents_flags+0x169/0x4c0
xfs_inactive_truncate+0xba/0x140
xfs_inactive+0x239/0x2a0
xfs_inodegc_worker+0xa3/0x210
? process_scheduled_works+0x273/0x550
process_scheduled_works+0x2da/0x550
worker_thread+0x180/0x350

Most of the Linux distributions default to voluntary preemption,
might_sleep() would yield CPU if needed. Thus they are not affected.
kworker/0:24+xf 298 [000] 7294.810021: probe:__cond_resched:
__cond_resched+0x5 ([kernel.kallsyms])
__kmem_cache_alloc_node+0x17c ([kernel.kallsyms])
__kmalloc+0x4d ([kernel.kallsyms])
kmem_alloc+0x7a ([kernel.kallsyms])
xfs_extent_busy_insert_list+0x2e ([kernel.kallsyms])
__xfs_free_extent+0xd3 ([kernel.kallsyms])
xfs_trans_free_extent+0x93 ([kernel.kallsyms])
xfs_extent_free_finish_item+0xf ([kernel.kallsyms])

kworker/0:24+xf 298 [000] 7294.810045: probe:__cond_resched:
__cond_resched+0x5 ([kernel.kallsyms])
down+0x11 ([kernel.kallsyms])
xfs_buf_lock+0x2c ([kernel.kallsyms])
xfs_buf_find_lock+0x62 ([kernel.kallsyms])
xfs_buf_get_map+0x1fd ([kernel.kallsyms])
xfs_buf_read_map+0x51 ([kernel.kallsyms])
xfs_trans_read_buf_map+0x1c5 ([kernel.kallsyms])
xfs_btree_read_buf_block.constprop.0+0xa1 ([kernel.kallsyms])
xfs_btree_lookup_get_block+0x97 ([kernel.kallsyms])
xfs_btree_lookup+0xc5 ([kernel.kallsyms])
xfs_alloc_lookup_eq+0x18 ([kernel.kallsyms])
xfs_free_ag_extent+0x63f ([kernel.kallsyms])
__xfs_free_extent+0xa7 ([kernel.kallsyms])
xfs_trans_free_extent+0x93 ([kernel.kallsyms])
xfs_extent_free_finish_item+0xf ([kernel.kallsyms])

Signed-off-by: Jian Wen <wenjian1@xiaomi.com>
---
fs/xfs/xfs_inode.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index c0f1c89786c2..194381e10472 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -4,6 +4,7 @@
* All Rights Reserved.
*/
#include <linux/iversion.h>
+#include <linux/sched.h>

#include "xfs.h"
#include "xfs_fs.h"
@@ -1383,6 +1384,8 @@ xfs_itruncate_extents_flags(
error = xfs_defer_finish(&tp);
if (error)
goto out;
+
+ cond_resched();
}

if (whichfork == XFS_DATA_FORK) {
--
2.25.1