From: Ye Bin <yebin10@xxxxxxxxxx>
There's a issue when remove scsi disk, the invalidate_inodes() function
cannot exit for a long time, then trigger hungtask:
INFO: task kworker/56:0:1391396 blocked for more than 122 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Workqueue: events_freezable virtscsi_handle_event [virtio_scsi]
Call Trace:
__schedule+0x33c/0x7f0
schedule+0x46/0xb0
schedule_preempt_disabled+0xa/0x10
__mutex_lock.constprop.0+0x22b/0x490
mutex_lock+0x52/0x70
scsi_scan_target+0x6d/0xf0
virtscsi_handle_event+0x152/0x1a0 [virtio_scsi]
process_one_work+0x1b2/0x350
worker_thread+0x49/0x310
kthread+0xfb/0x140
ret_from_fork+0x1f/0x30
PID: 540499 TASK: ffff9b15e504c080 CPU: 44 COMMAND: "kworker/44:0"
Call trace:
invalidate_inodes at ffffffff8f3b4784
__invalidate_device at ffffffff8f3dfea3
invalidate_partition at ffffffff8f526b49
del_gendisk at ffffffff8f5280fb
sd_remove at ffffffffc0186455 [sd_mod]
__device_release_driver at ffffffff8f738ab2
device_release_driver at ffffffff8f738bc4
bus_remove_device at ffffffff8f737f66
device_del at ffffffff8f73341b
__scsi_remove_device at ffffffff8f780340
scsi_remove_device at ffffffff8f7803a2
virtscsi_handle_event at ffffffffc017204f [virtio_scsi]
process_one_work at ffffffff8f1041f2
worker_thread at ffffffff8f104789
kthread at ffffffff8f109abb
ret_from_fork at ffffffff8f001d6f
As commit 04646aebd30b ("fs: avoid softlockups in s_inodes iterators")
introduces the retry logic. In the problem environment, the 'i_count'
of millions of files is not zero. As a result, the time slice for each
traversal to the matching inode process is almost used up, and then the
traversal is started from scratch. The worst-case scenario is that only
one inode can be processed after each wakeup. Because this process holds
a lock, other processes will be stuck for a long time, causing a series
of problems.
To solve the problem of repeated traversal from the beginning, each time
the CPU needs to be freed, a cursor is inserted into the linked list, and
the traversal continues from the cursor next time.
Fixes: 04646aebd30b ("fs: avoid softlockups in s_inodes iterators")
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
---
fs/inode.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index dc966990bda6..b78895af8779 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -857,11 +857,16 @@ static void dispose_list(struct list_head *head)
void evict_inodes(struct super_block *sb)
{
struct inode *inode, *next;
+ struct inode cursor;
LIST_HEAD(dispose);
+ cursor.i_state = I_CURSOR;
+ INIT_LIST_HEAD(&cursor.i_sb_list);
+ inode = list_entry(&sb->s_inodes, typeof(*inode), i_sb_list);
+
again:
spin_lock(&sb->s_inode_list_lock);
- sb_for_each_inodes_safe(inode, next, &sb->s_inodes) {
+ sb_for_each_inodes_continue_safe(inode, next, &sb->s_inodes) {
if (atomic_read(&inode->i_count))
continue;
@@ -886,12 +891,16 @@ void evict_inodes(struct super_block *sb)
* bit so we don't livelock.
*/
if (need_resched()) {
+ list_del(&cursor.i_sb_list);
+ list_add(&cursor.i_sb_list, &inode->i_sb_list);
+ inode = &cursor;
spin_unlock(&sb->s_inode_list_lock);
cond_resched();
dispose_list(&dispose);
goto again;
}
}
+ list_del(&cursor.i_sb_list);
spin_unlock(&sb->s_inode_list_lock);
dispose_list(&dispose);
@@ -907,11 +916,16 @@ EXPORT_SYMBOL_GPL(evict_inodes);
void invalidate_inodes(struct super_block *sb)
{
struct inode *inode, *next;
+ struct inode cursor;
LIST_HEAD(dispose);
+ cursor.i_state = I_CURSOR;
+ INIT_LIST_HEAD(&cursor.i_sb_list);
+ inode = list_entry(&sb->s_inodes, typeof(*inode), i_sb_list);
+
again:
spin_lock(&sb->s_inode_list_lock);
- sb_for_each_inodes_safe(inode, next, &sb->s_inodes) {
+ sb_for_each_inodes_continue_safe(inode, next, &sb->s_inodes) {
spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
spin_unlock(&inode->i_lock);
@@ -927,12 +941,16 @@ void invalidate_inodes(struct super_block *sb)
spin_unlock(&inode->i_lock);
list_add(&inode->i_lru, &dispose);
if (need_resched()) {
+ list_del(&cursor.i_sb_list);
+ list_add(&cursor.i_sb_list, &inode->i_sb_list);
+ inode = &cursor;
spin_unlock(&sb->s_inode_list_lock);
cond_resched();
dispose_list(&dispose);
goto again;
}
}
+ list_del(&cursor.i_sb_list);
spin_unlock(&sb->s_inode_list_lock);
dispose_list(&dispose);
--
2.34.1
