From: Henry Burns <henryburns@xxxxxxxxxx>
Subject: mm/z3fold.c: remove z3fold_migration trylock
z3fold_page_migrate() will never succeed because it attempts to acquire a
lock that has already been taken by migrate.c in __unmap_and_move().
__unmap_and_move() migrate.c
trylock_page(oldpage)
move_to_new_page(oldpage_newpage)
a_ops->migrate_page(oldpage, newpage)
z3fold_page_migrate(oldpage, newpage)
trylock_page(oldpage)
Link: http://lkml.kernel.org/r/20190710213238.91835-1-henryburns@xxxxxxxxxx
Fixes: 1f862989b04a ("mm/z3fold.c: support page migration")
Signed-off-by: Henry Burns <henryburns@xxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Vitaly Wool <vitalywool@xxxxxxxxx>
Cc: Vitaly Vul <vitaly.vul@xxxxxxxx>
Cc: Jonathan Adams <jwadams@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Snild Dolkow <snild@xxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 6 ------
1 file changed, 6 deletions(-)
--- a/mm/z3fold.c~mm-z3foldc-remove-z3fold_migration-trylock
+++ a/mm/z3fold.c
@@ -1350,16 +1350,11 @@ static int z3fold_page_migrate(struct ad
zhdr = page_address(page);
pool = zhdr_to_pool(zhdr);
- if (!trylock_page(page))
- return -EAGAIN;
-
if (!z3fold_page_trylock(zhdr)) {
- unlock_page(page);
return -EAGAIN;
}
if (zhdr->mapped_count != 0) {
z3fold_page_unlock(zhdr);
- unlock_page(page);
return -EBUSY;
}
new_zhdr = page_address(newpage);
@@ -1391,7 +1386,6 @@ static int z3fold_page_migrate(struct ad
queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
page_mapcount_reset(page);
- unlock_page(page);
put_page(page);
return 0;
}
_
