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Completely agree, just one little addition: Could you also add this why as comment to the code? When we stumble over this five years from now it is absolutely not obvious why we do this. Thanks, Christian. > > >> Signed-off-by: Guangming >> Signed-off-by: jianjiao zeng >> --- >> v2: 1. update size limitation as total_dram page size. >> 2. update commit message >> --- >> drivers/dma-buf/dma-heap.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c >> index 56bf5ad01ad5..e39d2be98d69 100644 >> --- a/drivers/dma-buf/dma-heap.c >> +++ b/drivers/dma-buf/dma-heap.c >> @@ -55,6 +55,8 @@ static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, >> struct dma_buf *dmabuf; >> int fd; >> >> + if (len / PAGE_SIZE > totalram_pages()) >> + return -EINVAL; > This seems sane. I know ION used to have some 1/2 of memory cap to > avoid unnecessary memory pressure on crazy allocations. > > Could you send again with an improved commit message? > > thanks > -john 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9D523C433F5 for ; Tue, 4 Jan 2022 07:48:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; 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charset="us-ascii"; Format="flowed" Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org Am 03.01.22 um 19:57 schrieb John Stultz: > On Mon, Dec 27, 2021 at 1:52 AM wrote: >> From: Guangming >> > Thanks for submitting this! > >> Add a size check for allcation since the allocation size is > nit: "allocation" above. > >> always less than the total DRAM size. > In general, it might be good to add more context to the commit message > to better answer *why* this change is needed rather than what the > change is doing. ie: What negative thing happens without this change? > And so how does this change avoid or improve things? Completely agree, just one little addition: Could you also add this why as comment to the code? When we stumble over this five years from now it is absolutely not obvious why we do this. Thanks, Christian. > > >> Signed-off-by: Guangming >> Signed-off-by: jianjiao zeng >> --- >> v2: 1. update size limitation as total_dram page size. >> 2. update commit message >> --- >> drivers/dma-buf/dma-heap.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c >> index 56bf5ad01ad5..e39d2be98d69 100644 >> --- a/drivers/dma-buf/dma-heap.c >> +++ b/drivers/dma-buf/dma-heap.c >> @@ -55,6 +55,8 @@ static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, >> struct dma_buf *dmabuf; >> int fd; >> >> + if (len / PAGE_SIZE > totalram_pages()) >> + return -EINVAL; > This seems sane. I know ION used to have some 1/2 of memory cap to > avoid unnecessary memory pressure on crazy allocations. > > Could you send again with an improved commit message? > > thanks > -john _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6C6F0C4332F for ; Tue, 4 Jan 2022 07:48:10 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8553110E13C; Tue, 4 Jan 2022 07:48:09 +0000 (UTC) Received: from NAM12-BN8-obe.outbound.protection.outlook.com (mail-bn8nam12on2061.outbound.protection.outlook.com [40.107.237.61]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3069010E13C for ; 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Tue, 4 Jan 2022 07:48:05 +0000 Subject: Re: [PATCH v2] dma-buf: dma-heap: Add a size check for allocation To: John Stultz , guangming.cao@mediatek.com References: <20211217094104.24977-1-guangming.cao@mediatek.com> <20211227095102.6054-1-guangming.cao@mediatek.com> From: =?UTF-8?Q?Christian_K=c3=b6nig?= Message-ID: Date: Tue, 4 Jan 2022 08:47:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: AM6PR08CA0013.eurprd08.prod.outlook.com (2603:10a6:20b:b2::25) To MWHPR1201MB0192.namprd12.prod.outlook.com (2603:10b6:301:5a::14) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: dbe28ac9-d954-4061-97a1-08d9cf568a6e X-MS-TrafficTypeDiagnostic: MWHPR1201MB0238:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:1332; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Completely agree, just one little addition: Could you also add this why as comment to the code? When we stumble over this five years from now it is absolutely not obvious why we do this. Thanks, Christian. > > >> Signed-off-by: Guangming >> Signed-off-by: jianjiao zeng >> --- >> v2: 1. update size limitation as total_dram page size. >> 2. update commit message >> --- >> drivers/dma-buf/dma-heap.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c >> index 56bf5ad01ad5..e39d2be98d69 100644 >> --- a/drivers/dma-buf/dma-heap.c >> +++ b/drivers/dma-buf/dma-heap.c >> @@ -55,6 +55,8 @@ static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, >> struct dma_buf *dmabuf; >> int fd; >> >> + if (len / PAGE_SIZE > totalram_pages()) >> + return -EINVAL; > This seems sane. I know ION used to have some 1/2 of memory cap to > avoid unnecessary memory pressure on crazy allocations. > > Could you send again with an improved commit message? > > thanks > -john 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EFAFAC433F5 for ; Tue, 4 Jan 2022 07:49:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; 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charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Am 03.01.22 um 19:57 schrieb John Stultz: > On Mon, Dec 27, 2021 at 1:52 AM wrote: >> From: Guangming >> > Thanks for submitting this! > >> Add a size check for allcation since the allocation size is > nit: "allocation" above. > >> always less than the total DRAM size. > In general, it might be good to add more context to the commit message > to better answer *why* this change is needed rather than what the > change is doing. ie: What negative thing happens without this change? > And so how does this change avoid or improve things? Completely agree, just one little addition: Could you also add this why as comment to the code? When we stumble over this five years from now it is absolutely not obvious why we do this. Thanks, Christian. > > >> Signed-off-by: Guangming >> Signed-off-by: jianjiao zeng >> --- >> v2: 1. update size limitation as total_dram page size. >> 2. update commit message >> --- >> drivers/dma-buf/dma-heap.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c >> index 56bf5ad01ad5..e39d2be98d69 100644 >> --- a/drivers/dma-buf/dma-heap.c >> +++ b/drivers/dma-buf/dma-heap.c >> @@ -55,6 +55,8 @@ static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, >> struct dma_buf *dmabuf; >> int fd; >> >> + if (len / PAGE_SIZE > totalram_pages()) >> + return -EINVAL; > This seems sane. I know ION used to have some 1/2 of memory cap to > avoid unnecessary memory pressure on crazy allocations. > > Could you send again with an improved commit message? > > thanks > -john _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel