On 2020/11/10 1:00, Jaegeuk Kim wrote:
Light reported sometimes shinker gets nat_cnt < dirty_nat_cnt resulting in
I didn't get the problem clearly, did you mean __count_nat_entries() will
give the wrong shrink count due to race condition? should there be a lock
while reading these two variables?
wrong do_shinker work. Basically the two counts should not happen like that.
So, I suspect this race condtion where:
- f2fs_try_to_free_nats __flush_nat_entry_set
nat_cnt=2, dirty_nat_cnt=2
__clear_nat_cache_dirty
spin_lock(nat_list_lock)
list_move()
spin_unlock(nat_list_lock)
spin_lock(nat_list_lock)
list_del()
spin_unlock(nat_list_lock)
nat_cnt=1, dirty_nat_cnt=2
nat_cnt=1, dirty_nat_cnt=1
nm_i->nat_cnt and nm_i->dirty_nat_cnt were protected by
nm_i->nat_tree_lock, I didn't see why expanding nat_list_lock range
will help... since there are still places nat_list_lock() didn't
cover these two reference counts.
Thanks,
Reported-by: Light Hsieh <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>
---
fs/f2fs/node.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 42394de6c7eb..e8ec65e40f06 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -269,11 +269,10 @@ static void __clear_nat_cache_dirty(struct f2fs_nm_info
*nm_i,
{
spin_lock(&nm_i->nat_list_lock);
list_move_tail(&ne->list, &nm_i->nat_entries);
- spin_unlock(&nm_i->nat_list_lock);
-
set_nat_flag(ne, IS_DIRTY, false);
set->entry_cnt--;
nm_i->dirty_nat_cnt--;
+ spin_unlock(&nm_i->nat_list_lock);
}
static unsigned int __gang_lookup_nat_set(struct f2fs_nm_info *nm_i,
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