linux-kernel - [PATCH v2] mm/page_alloc: Dedupe some memcg uncharging logic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231108164920.3401565-1-jackmanb@google.com>
Date:   Wed,  8 Nov 2023 16:49:20 +0000
From:   Brendan Jackman <jackmanb@...gle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <muchun.song@...ux.dev>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH v2] mm/page_alloc: Dedupe some memcg uncharging logic

The duplication makes it seem like some work is required before
uncharging in the !PageHWPoison case. But it isn't, so we can simplify
the code a little.

Note the PageMemcgKmem check is redundant, but I've left it in as it
avoids an unnecessary function call.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 mm/page_alloc.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 733732e7e0ba..dd5e8a759d27 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1086,13 +1086,11 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	trace_mm_page_free(page, order);
 	kmsan_free_page(page, order);
 
+	if (memcg_kmem_online() && PageMemcgKmem(page))
+		__memcg_kmem_uncharge_page(page, order);
+
 	if (unlikely(PageHWPoison(page)) && !order) {
-		/*
-		 * Do not let hwpoison pages hit pcplists/buddy
-		 * Untie memcg state and reset page's owner
-		 */
-		if (memcg_kmem_online() && PageMemcgKmem(page))
-			__memcg_kmem_uncharge_page(page, order);
+		/* Do not let hwpoison pages hit pcplists/buddy */
 		reset_page_owner(page, order);
 		page_table_check_free(page, order);
 		return false;
@@ -1123,8 +1121,6 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	}
 	if (PageMappingFlags(page))
 		page->mapping = NULL;
-	if (memcg_kmem_online() && PageMemcgKmem(page))
-		__memcg_kmem_uncharge_page(page, order);
 	if (is_check_pages_enabled()) {
 		if (free_page_is_bad(page))
 			bad++;
-- 
2.42.0.869.gea05f2083d-goog