From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C69F82C80 for ; Fri, 8 Apr 2022 20:09:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C6C3C385A3; Fri, 8 Apr 2022 20:09:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1649448554; bh=CqgdUQ8KtmQ/Yioj4EEH5I++u5nh/s1yL09Oz1Ljgus=; h=Date:To:From:In-Reply-To:Subject:From; b=lurkYQeuelUK9MzaQvPWE59Mc2SYGwBMwF5zstmCGj2AAUTY2zxII0D/2B+TR6M+t zGJp1GhQsY6gZYogUUO5cUbUahD0DTXo1pShk8RZSvHH4Wz7RN/Y/QLrLdxRKyBIG8 Cvy8rjaytF8h3A10SHPnJ1U31nUmg3pN3jOf9ZOw= Date: Fri, 08 Apr 2022 13:09:13 -0700 To: songmuchun@bytedance.com,shakeelb@google.com,roman.gushchin@linux.dev,mhocko@suse.com,longman@redhat.com,hannes@cmpxchg.org,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220408130819.a89195e527ce58dfbe0700b9@linux-foundation.org> Subject: [patch 8/9] mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()" Message-Id: <20220408200914.7C6C3C385A3@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Andrew Morton Subject: mm/list_lru.c: revert "mm/list_lru: optimize memcg_reparent_list_lru_node()" 405cc51fc1049c73 ("mm/list_lru: optimize memcg_reparent_list_lru_node()") has subtle races which are proving ugly to fix. Revert the original optimization. If quantitative testing indicates that we have a significant problem here then other implementations can be looked at. Fixes: 405cc51fc1049c73 ("mm/list_lru: optimize memcg_reparent_list_lru_node()") Acked-by: Shakeel Butt Reviewed-by: Muchun Song Acked-by: Michal Hocko Cc: Waiman Long Cc: Roman Gushchin Cc: Johannes Weiner Signed-off-by: Andrew Morton --- mm/list_lru.c | 6 ------ 1 file changed, 6 deletions(-) --- a/mm/list_lru.c~mm-list_lruc-revert-mm-list_lru-optimize-memcg_reparent_list_lru_node +++ a/mm/list_lru.c @@ -395,12 +395,6 @@ static void memcg_reparent_list_lru_node struct list_lru_one *src, *dst; /* - * If there is no lru entry in this nlru, we can skip it immediately. - */ - if (!READ_ONCE(nlru->nr_items)) - return; - - /* * Since list_lru_{add,del} may be called under an IRQ-safe lock, * we have to use IRQ-safe primitives here to avoid deadlock. */ _