On 11/10, Chao Yu wrote: > 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.
Yeah, I missed nat_tree_lock, and indeed it should cover this. So, the problem is Light reported subtle case of nat_cnt < dirty_nat_cnt in shrink_count. We may need to use nat_tree_lock in shrink_count? > > 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, > > _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
