From patchwork Sat Sep 19 04:20:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 309517 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79358C43464 for ; Sat, 19 Sep 2020 04:20:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44BCE2344C for ; Sat, 19 Sep 2020 04:20:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600489205; bh=/967+0nd3QfFE67e6Yxm69sBtWBBFlo25Sam1ALVV4I=; h=Date:From:To:Subject:In-Reply-To:List-ID:From; b=X9eb5sspj9Bvsm28P2QN1Ma7/RV/jvUdVR409WjyhaU9bKM1sp1lFz0FUb94MBvJn ohs7lrhlfNgO/XI6QSBfdUnOMRBwIacQqPfmuKuZj2hVyTF13c3U29ycJVuofxeN5H qoY3/RL/W0amkSQfRVy1qYssKKTvZ5suhSkvD4NM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726152AbgISEUE (ORCPT ); Sat, 19 Sep 2020 00:20:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:54360 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726009AbgISEUE (ORCPT ); Sat, 19 Sep 2020 00:20:04 -0400 Received: from localhost.localdomain (c-71-198-47-131.hsd1.ca.comcast.net [71.198.47.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B7902235FA; Sat, 19 Sep 2020 04:20:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600489204; bh=/967+0nd3QfFE67e6Yxm69sBtWBBFlo25Sam1ALVV4I=; h=Date:From:To:Subject:In-Reply-To:From; b=KoADUO6ASU2e5+r6O8uV1RfC5GKpAEjYkJLRtzfT0Pj3rBq9vosSnCJZrhaDYBFXJ +bVsqMVNLoHRpvKGfCkfflrNoGX8Uz/sDC2AEjb/JOwhDsVgksTi3peN0YCVPBEQpj hDv4sy6d0/z3GrZ2FGf1bAEzRh3HvY530wM4TPz0= Date: Fri, 18 Sep 2020 21:20:03 -0700 From: Andrew Morton To: akpm@linux-foundation.org, alex.shi@linux.alibaba.com, cai@lca.pw, hannes@cmpxchg.org, hughd@google.com, linux-mm@kvack.org, mhocko@suse.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, shakeelb@google.com, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 02/15] ksm: reinstate memcg charge on copied pages Message-ID: <20200919042003.LTbtjVRr7%akpm@linux-foundation.org> In-Reply-To: <20200918211925.7e97f0ef63d92f5cfe5ccbc5@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hugh Dickins Subject: ksm: reinstate memcg charge on copied pages Patch series "mm: fixes to past from future testing". Here's a set of independent fixes against 5.9-rc2: prompted by testing Alex Shi's "warning on !memcg" and lru_lock series, but I think fit for 5.9 - though maybe only the first for stable. This patch (of 5): In 5.8 some instances of memcg charging in do_swap_page() and unuse_pte() were removed, on the understanding that swap cache is now already charged at those points; but a case was missed, when ksm_might_need_to_copy() has decided it must allocate a substitute page: such pages were never charged. Fix it inside ksm_might_need_to_copy(). This was discovered by Alex Shi's prospective commit "mm/memcg: warning on !memcg after readahead page charged". But there is a another surprise: this also fixes some rarer uncharged PageAnon cases, when KSM is configured in, but has never been activated. ksm_might_need_to_copy()'s anon_vma->root and linear_page_index() check sometimes catches a case which would need to have been copied if KSM were turned on. Or that's my optimistic interpretation (of my own old code), but it leaves some doubt as to whether everything is working as intended there - might it hint at rare anon ptes which rmap cannot find? A question not easily answered: put in the fix for missed memcg charges. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301343270.5954@eggly.anvils Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301358020.5954@eggly.anvils Fixes: 4c6355b25e8b ("mm: memcontrol: charge swapin pages on instantiation") Signed-off-by: Hugh Dickins Reviewed-by: Shakeel Butt Acked-by: Johannes Weiner Cc: Alex Shi Cc: Michal Hocko Cc: Mike Kravetz Cc; Matthew Wilcox Cc: Qian Cai Cc: [5.8] Signed-off-by: Andrew Morton --- mm/ksm.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/ksm.c~ksm-reinstate-memcg-charge-on-copied-pages +++ a/mm/ksm.c @@ -2586,6 +2586,10 @@ struct page *ksm_might_need_to_copy(stru return page; /* let do_swap_page report the error */ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); + if (new_page && mem_cgroup_charge(new_page, vma->vm_mm, GFP_KERNEL)) { + put_page(new_page); + new_page = NULL; + } if (new_page) { copy_user_highpage(new_page, page, address, vma);