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 2FC72CCA492 for ; Tue, 7 Jun 2022 21:46:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382175AbiFGVql (ORCPT ); Tue, 7 Jun 2022 17:46:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378379AbiFGUvm (ORCPT ); Tue, 7 Jun 2022 16:51:42 -0400 Received: from mail.cybernetics.com (mail.cybernetics.com [173.71.130.66]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06C23115A43 for ; Tue, 7 Jun 2022 11:42:10 -0700 (PDT) X-ASG-Debug-ID: 1654627329-1cf43917f33965c0001-xx1T2L Received: from cybernetics.com ([10.10.4.126]) by mail.cybernetics.com with ESMTP id 79iRHZabdgVhHOFB; Tue, 07 Jun 2022 14:42:09 -0400 (EDT) X-Barracuda-Envelope-From: tonyb@cybernetics.com X-ASG-Whitelist: Client DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=cybernetics.com; s=mail; bh=QbGgNEs9DYDdDETge9nU6qZiAN8p+i0+8LJZVlYu570=; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:References:Cc:To:From: Content-Language:Subject:MIME-Version:Date:Message-ID; b=jsWpK2MOULqWUEtEYypu BZF113V20OKS/bUvhZVyqHKTY3exH3pnTa1QbMsrI0H9CbQGv9hAAG8PzWuG8R9hLqsUNEYUi26EP 8sXIBWYag6D+3OMUTNSodUaPd+OaQi/fx5JrYEKxj7ulxkltkon72+19JDoSSGToGumE1b7Fto= Received: from [10.157.2.224] (HELO [192.168.200.1]) by cybernetics.com (CommuniGate Pro SMTP 7.1.1) with ESMTPS id 11859424; Tue, 07 Jun 2022 14:42:09 -0400 Message-ID: <6eaea467-cc50-acbd-6232-892011fc803c@cybernetics.com> Date: Tue, 7 Jun 2022 14:42:09 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: [PATCH v6 04/11] dmapool: fix boundary comparison Content-Language: en-US X-ASG-Orig-Subj: [PATCH v6 04/11] dmapool: fix boundary comparison From: Tony Battersby To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: iommu@lists.linux-foundation.org, kernel-team@fb.com, Matthew Wilcox , Keith Busch , Andy Shevchenko , Robin Murphy , Tony Lindgren References: <340ff8ef-9ff5-7175-c234-4132bbdfc5f7@cybernetics.com> In-Reply-To: <340ff8ef-9ff5-7175-c234-4132bbdfc5f7@cybernetics.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Barracuda-Connect: UNKNOWN[10.10.4.126] X-Barracuda-Start-Time: 1654627329 X-Barracuda-URL: https://10.10.4.122:443/cgi-mod/mark.cgi X-Barracuda-BRTS-Status: 1 X-Virus-Scanned: by bsmtpd at cybernetics.com X-Barracuda-Scan-Msg-Size: 1388 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fix the boundary comparison when constructing the list of free blocks for the case that 'size' is a power of two. Since 'boundary' is also a power of two, that would make 'boundary' a multiple of 'size', in which case a single block would never cross the boundary. This bug would cause some of the allocated memory to be wasted (but not leaked). Example: size = 512 boundary = 2048 allocation = 4096 Address range 0 - 511 512 - 1023 1024 - 1535 1536 - 2047 * 2048 - 2559 2560 - 3071 3072 - 3583 3584 - 4095 * Prior to this fix, the address ranges marked with "*" would not have been used even though they didn't cross the given boundary. Fixes: e34f44b3517f ("pool: Improve memory usage for devices which can't cross boundaries") Signed-off-by: Tony Battersby --- mm/dmapool.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/dmapool.c b/mm/dmapool.c index f85d6bde2205..122781fe2c03 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -201,7 +201,7 @@ static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) do { unsigned int next = offset + pool->size; - if (unlikely((next + pool->size) >= next_boundary)) { + if (unlikely((next + pool->size) > next_boundary)) { next = next_boundary; next_boundary += pool->boundary; } -- 2.25.1