linux-kernel - [PATCH 07/11] PageSlab: eliminate unnecessary compound

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Message-Id: <20211012180148.1669685-8-hannes@cmpxchg.org>
Date:   Tue, 12 Oct 2021 14:01:44 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     linux-mm@...ck.org
Cc:     Matthew Wilcox <willy@...radead.org>,
        Kent Overstreet <kent.overstreet@...il.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>, Roman Gushchin <guro@...com>,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: [PATCH 07/11] PageSlab: eliminate unnecessary compound_head() call in mm/slab

kmem_freepages() is only ever called on the full slab, i.e. the
headpage. Further, after the PageSlab() check, the callsite continues
with a series of operations that are not legal on tailpages and would
trigger asserts on their own already.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 mm/slab.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab.c b/mm/slab.c
index 829f2b6d4af7..d0f725637663 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1396,7 +1396,7 @@ static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
 {
 	int order = cachep->gfporder;
 
-	BUG_ON(!PageSlab(compound_head(page)));
+	BUG_ON(!PageSlab(page));
 	__ClearPageSlabPfmemalloc(page);
 	__ClearPageSlab(page);
 	page_mapcount_reset(page);
-- 
2.32.0