From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A3A1C19F2D for ; Tue, 9 Aug 2022 10:49:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233344AbiHIKt5 (ORCPT ); Tue, 9 Aug 2022 06:49:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231802AbiHIKty (ORCPT ); Tue, 9 Aug 2022 06:49:54 -0400 Received: from mail-oi1-x22e.google.com (mail-oi1-x22e.google.com [IPv6:2607:f8b0:4864:20::22e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4D06120A3 for ; Tue, 9 Aug 2022 03:49:52 -0700 (PDT) Received: by mail-oi1-x22e.google.com with SMTP id bb16so13330458oib.11 for ; Tue, 09 Aug 2022 03:49:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=wc4pc4XjzEcCEnj/rsl5k2xYOk9EdSwkRXBZHUsSZMk=; b=cNv9ey+nvgOoNPDu3fYAV530sBBW3pHAx4VkhkoMEqb4HXlxJJhwrYW2fhuoGEabOq GwEcSrUH8Ssfa8En8W/sqL4jkAziGYFUMu3Yw2lI2ohYSQLlk3XHeKcFDHqsmLfTOUT/ MH+Xe1J4clCsuVxQnnKV9K1h8Tkqo9fsIuazgNSZWzSg2dgNzDpGt92vAOxeuWDRKwnA wUyMfb0rBy59VQx2S519n5z1HVIA+2+XlJyLAsM69t+G4iqI5j6o+SEM91l9SNcJEBcG 6R70Z2EaXlFGVWFJrhsEKuHagQ8lmBHYM7LgfmSictkfHCyM3CGVM67k7qTcgRDM3qEe eP+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=wc4pc4XjzEcCEnj/rsl5k2xYOk9EdSwkRXBZHUsSZMk=; b=DffQGGn/vPm94zu+G9ufj1HFPa0DE4f3px5vUXBldVuvC9jsAMpr48ur4xqXyhltdy KBv74HCEKwzFVAUloDml3MI8xfgRumbHfOmFXxeK5O41D0+AB+9bifAhAgTBKvOCqXqN JNEt/uVuqOuC+yhfoMK9OrgB+zWfoTVvQ6d+ASQb6SkULXzP5aTF7nb6LUE8UKKm4AFY Gm+F59jtJbYurTqs6jtE2hXyIFvkpRoFcvFUN/abkUTAsdoaewG0BPFk/HEZDCaf6FFA QySYeb60BCOlkuWv1rE8TzHIqjtMIkALsGt6bcV3yGcIHq0gb+rpUzga7Cy3UgSF36da +xzg== X-Gm-Message-State: ACgBeo0dbU5MhVmOEJ1TE5R/MRKMWmBgMwfkdgTIK49qawYNfLJf8Y9v yX70/YpTOnr3sauab6Nw8KzA1/7WiP/KbwwK X-Google-Smtp-Source: AA6agR4PYo3SWTvvtd2qU1lQNNRTyI1XAdbmd19eqOVySGmVsFyA0jsDNS8hDoQ6wKTbK/2nUV0IEA== X-Received: by 2002:a17:90b:4b4d:b0:1f5:164f:f7c4 with SMTP id mi13-20020a17090b4b4d00b001f5164ff7c4mr34144617pjb.131.1660042181117; Tue, 09 Aug 2022 03:49:41 -0700 (PDT) Received: from C02DV8HUMD6R.bytedance.net ([139.177.225.254]) by smtp.gmail.com with ESMTPSA id b11-20020a62a10b000000b0052def2e20dasm10270377pff.167.2022.08.09.03.49.37 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Aug 2022 03:49:40 -0700 (PDT) From: Abel Wu To: Andrew Morton , Vlastimil Babka , Michal Hocko , Mel Gorman , Muchun Song Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Abel Wu Subject: [PATCH] mm/mempolicy: fix lock contention on mems_allowed Date: Tue, 9 Aug 2022 18:49:27 +0800 Message-Id: <20220809104927.44366-1-wuyun.abel@bytedance.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The mems_allowed field can be modified by other tasks, so it isn't safe to access it with alloc_lock unlocked even in the current process context. Fixes: 78b132e9bae9 ("mm/mempolicy: remove or narrow the lock on current") Signed-off-by: Abel Wu --- mm/mempolicy.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index d39b01fd52fe..ae422e44affb 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -855,12 +855,14 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags, goto out; } + task_lock(current); ret = mpol_set_nodemask(new, nodes, scratch); if (ret) { + task_unlock(current); mpol_put(new); goto out; } - task_lock(current); + old = current->mempolicy; current->mempolicy = new; if (new && new->mode == MPOL_INTERLEAVE) @@ -1295,7 +1297,9 @@ static long do_mbind(unsigned long start, unsigned long len, NODEMASK_SCRATCH(scratch); if (scratch) { mmap_write_lock(mm); + task_lock(current); err = mpol_set_nodemask(new, nmask, scratch); + task_unlock(current); if (err) mmap_write_unlock(mm); } else -- 2.31.1