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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 6AD17C432C0 for ; Tue, 3 Dec 2019 18:35:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2896E20637 for ; Tue, 3 Dec 2019 18:35:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="FmskHlzg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727158AbfLCSfi (ORCPT ); Tue, 3 Dec 2019 13:35:38 -0500 Received: from mail-qt1-f196.google.com ([209.85.160.196]:38883 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726564AbfLCSfi (ORCPT ); Tue, 3 Dec 2019 13:35:38 -0500 Received: by mail-qt1-f196.google.com with SMTP id 14so4814668qtf.5 for ; Tue, 03 Dec 2019 10:35:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YOfocbvIxC0iu9uOHcUapzST4lCL7cP23eKj1vMSlro=; b=FmskHlzgPfYc9RuTSKhCb1dS/OuIvm1U1ED45iv8aC9CBBl5CaalVD2LOcKK2XR+tP W5s3zggyrlhZBVGP7rJHGlQ6u5DtBCrk8eT6SOXXEJXbKM+2+7TNFSOxEcMTCII7GEL3 +VIyLO2dQMMa2wRYUXRtXHUuBqgMkp/PLH35Sbp5WUEmefM6G6jTk0igw54lN53rRc+x Xy0YCezqKFjO5aOLkmi0vfWq8XF09PMhFyt7s344i+9M8BmShGzKQMnTFN5c48W925cV OAdoKdNcBmel2qHgYsxxtwEhWYoqjRoiC/W1SIZrtC7Y++zjE3Pg5AbC/WJQFchVBDTj irnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=YOfocbvIxC0iu9uOHcUapzST4lCL7cP23eKj1vMSlro=; b=hpi+rqvLFywLI2ElVD2OfTkRdQNfq0R3CkPHMa5vkbffelToOuAZ63MQ6U3zraMMNa jqqKXWDG7WQj3nCU48npvmWCjpkUhIRDoFLZVcpXOIruBBCk10D6jUKpxwwVGy/dS/K9 iR7TQPZ8KhQjc2pwd92acUIeKNMxVShRSQr7t2XodHOKpHwEAfeoGLt76rSU7M02FJpv 8qZdia8YaM1j/b7zCt4x2QUF7EfL5UaN5yF6Gu+WfVs3VusrX9Uy7IG41pKORC2Oi9Sl RbBm2ZcbKQKohTozC1scMWp5gXN+9vn8b8HS6gvrzdZAOmAzI6SMaUKgpFSu177ZCuAp sorw== X-Gm-Message-State: APjAAAWB3xHJuddKbimydoHo+1Jem4Fo6fUsBBGJxVl2qN4ExkMOqrER cnOCO3rAeLyp4v3We9+SG+Yb5baJkYY= X-Google-Smtp-Source: APXvYqwQFSPsMhtxC9HqmnfodmktUCuzthfKi5QH/SwAfSrFRLR3rXrYeh9SygKdg/E9JSDU9lKPPA== X-Received: by 2002:ac8:6f09:: with SMTP id g9mr6529852qtv.275.1575398137095; Tue, 03 Dec 2019 10:35:37 -0800 (PST) Received: from localhost ([2620:10d:c091:500::3:cbfe]) by smtp.gmail.com with ESMTPSA id d15sm2184192qti.69.2019.12.03.10.35.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Dec 2019 10:35:36 -0800 (PST) From: Johannes Weiner To: Peter Zijlstra Cc: Jingfeng Xie , Suren Baghdasaryan , linux-kernel@vger.kernel.org Subject: [PATCH 2/2] psi: fix a division error in psi poll() Date: Tue, 3 Dec 2019 13:35:24 -0500 Message-Id: <20191203183524.41378-3-hannes@cmpxchg.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203183524.41378-1-hannes@cmpxchg.org> References: <20191203183524.41378-1-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The psi window size is a u64 an can be up to 10 seconds right now, which exceeds the lower 32 bits of the variable. We currently use div_u64 for it, which is meant only for 32-bit divisors. The result is garbage pressure sampling values and even potential div0 crashes. Use div64_u64. Signed-off-by: Johannes Weiner Reviewed-by: Suren Baghdasaryan --- kernel/sched/psi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 970db4686dd4..ce8f6748678a 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -482,7 +482,7 @@ static u64 window_update(struct psi_window *win, u64 now, u64 value) u32 remaining; remaining = win->size - elapsed; - growth += div_u64(win->prev_growth * remaining, win->size); + growth += div64_u64(win->prev_growth * remaining, win->size); } return growth; -- 2.24.0