From df6f0f1d0cf091947bb621cfdada4c82c1f05c4b Mon Sep 17 00:00:00 2001
From: Miaohe Lin <linmiaohe@huawei.com>
Date: Fri, 29 Apr 2022 14:40:43 +0800
Subject: [PATCH] mm/z3fold: remove buggy use of stale list for allocation
Currently if z3fold couldn't find an unbuddied page it would first try to
pull a page off the stale list. But this approach is problematic. If
init z3fold page fails later, the page should be freed via
free_z3fold_page to clean up the relevant resource instead of using
__free_page directly. And if page is successfully reused, it will BUG_ON
later in __SetPageMovable because it's already non-lru movable page, i.e.
PAGE_MAPPING_MOVABLE is already set in page->mapping. In order to fix all
of these issues, we can simply remove the buggy use of stale list for
allocation because can_sleep should always be false and we never really
hit the reusing code path now.
Link: https://lkml.kernel.org/r/20220429064051.61552-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/z3fold.c | 23 +----------------------
1 file changed, 1 insertion(+), 22 deletions(-)
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 5d8c21f2bc592..4e6814c5694fa 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1102,28 +1102,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
bud = FIRST;
}
- page = NULL;
- if (can_sleep) {
- spin_lock(&pool->stale_lock);
- zhdr = list_first_entry_or_null(&pool->stale,
- struct z3fold_header, buddy);
- /*
- * Before allocating a page, let's see if we can take one from
- * the stale pages list. cancel_work_sync() can sleep so we
- * limit this case to the contexts where we can sleep
- */
- if (zhdr) {
- list_del(&zhdr->buddy);
- spin_unlock(&pool->stale_lock);
- cancel_work_sync(&zhdr->work);
- page = virt_to_page(zhdr);
- } else {
- spin_unlock(&pool->stale_lock);
- }
- }
- if (!page)
- page = alloc_page(gfp);
-
+ page = alloc_page(gfp);
if (!page)
return -ENOMEM;
--
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