From patchwork Mon Sep 21 16:28:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 309370 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=-11.2 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,USER_AGENT_GIT 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 D2916C43468 for ; Mon, 21 Sep 2020 16:54:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A3E832076E for ; Mon, 21 Sep 2020 16:54:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600707251; bh=JPG2gxzH8/PmMe7MPg6i78jrQ21xF4EspNNevikwD7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TC8vvSxgbvflYEhG/lVZKTUZWBZGmoMKnYgS1zSV82gZ/Dp9USh8v0hPnBBk6Uq9w uQNZlJs4k2ZOtiHr9prnKqU32DSVXS7twooQ8x7jWx+C5teqIlmbSGlk8DErTVs+i5 24ulX3BiZWQgf3Z5kBRW5qXdhw0pzuSh4ts4AG3s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729745AbgIUQqt (ORCPT ); Mon, 21 Sep 2020 12:46:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:53272 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727231AbgIUQqs (ORCPT ); Mon, 21 Sep 2020 12:46:48 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 456192388B; Mon, 21 Sep 2020 16:46:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600706808; bh=JPG2gxzH8/PmMe7MPg6i78jrQ21xF4EspNNevikwD7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CtNTOnDoC1sohP+qx+UQ9fNuLVJAWWW/DyfM0hSt5Ex7m3/6pyKeKBomtZzCExeRA CmQcB+cjXnY3bLbMpFfIAWvlgdRWw7/n8Gm5HoFGWA2PZq3zBvjXgpDGO3xbIW4gZ5 PIn6SkAQcSkO7Kg/nhRFzfNtNaNPRa/HjrjKVoJA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hugh Dickins , Andrew Morton , Shakeel Butt , Johannes Weiner , Alex Shi , Michal Hocko , Mike Kravetz , Qian Cai , Linus Torvalds Subject: [PATCH 5.8 103/118] ksm: reinstate memcg charge on copied pages Date: Mon, 21 Sep 2020 18:28:35 +0200 Message-Id: <20200921162041.161799840@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200921162036.324813383@linuxfoundation.org> References: <20200921162036.324813383@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hugh Dickins commit 62fdb1632bcbed30c40f6bd2b58297617e442658 upstream. 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. Cc; Matthew Wilcox Fixes: 4c6355b25e8b ("mm: memcontrol: charge swapin pages on instantiation") Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Reviewed-by: Shakeel Butt Acked-by: Johannes Weiner Cc: Alex Shi Cc: Michal Hocko Cc: Mike Kravetz Cc: Qian Cai Cc: [5.8] 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 Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/ksm.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2585,6 +2585,10 @@ 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);