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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01095C25B74 for ; Thu, 9 May 2024 04:51:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5CC636B0082; Thu, 9 May 2024 00:51:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 57CA26B0083; Thu, 9 May 2024 00:51:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 46A666B0088; Thu, 9 May 2024 00:51:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 2969B6B0082 for ; Thu, 9 May 2024 00:51:25 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B0927411FE for ; Thu, 9 May 2024 04:51:23 +0000 (UTC) X-FDA: 82097633646.03.2AEB821 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf19.hostedemail.com (Postfix) with ESMTP id 50A641A0010 for ; Thu, 9 May 2024 04:51:21 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=TXK3jkUV; spf=none (imf19.hostedemail.com: domain of BATV+16439c8c750d17eda2cb+7564+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+16439c8c750d17eda2cb+7564+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1715230282; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=RaN5985F7FCduVrYhbHTOUfpVUxqMFRtvYN9eBGKgx4=; b=SCApGBhiqZQqVI/s6QVllM+aWZl7dTrHywnoPo7fC6YbE6iavNKxTw6301ckcHmB6sg7lM Ql5EyVknLeNmJodfYayJAGoWpjgBiHbEc+98pUDzsQ4//DiQF5qwT9Bho1PRkE/vtoSJxq WVbVcoGC8o5QxjYzETIOjx0e/Tu1m2w= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=TXK3jkUV; spf=none (imf19.hostedemail.com: domain of BATV+16439c8c750d17eda2cb+7564+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+16439c8c750d17eda2cb+7564+infradead.org+hch@bombadil.srs.infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1715230282; a=rsa-sha256; cv=none; b=PErz2s6y5AX6aXv7tOspMqZOP4vcVB1FE5VEJnlfX91NvyCVj/wdV8TVzU5zBPm1CRr/rj /ulW2rUIHorCHF1WWI+E5TWgHdYQ7MXCnGnJ4meC51oll8C2I6VW5QKuGCYfOVHWLsvki1 ZkSQsl1tQLwOhoWGo7fosCo97poxbls= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=RaN5985F7FCduVrYhbHTOUfpVUxqMFRtvYN9eBGKgx4=; b=TXK3jkUVA6GFKp6bn67mzx5jZz D2KALZM05btPADagOJbnT/k+0uIxFXiMzTmxD6sBFAtI5bdtOf9jgr54MpVzqt6mdnSZ65tV/vkN1 OcXdcEvfyS+vR3Ur+8gn9XMhzHAo1ce+J9qc9hCKHaXnEaVPDDUVGoh0XYjINiJN3yOqofq4M4NeH b33qnKTfM9kDtLcNHWViJ5kEI5yDVDWqK3XRvGg2a296rSock9iZfgnC5HwbqJq1jOFdedraJTzTp F4SLlC1iw0IxV1piJNh4wx15Xktgy90pAnwN4DgGk45yyWWnok/vRC7hC25pd5IKQ8TjlyCMfHQ+o e7sbHNfw==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s4vkR-00000000Lth-2TLR; Thu, 09 May 2024 04:51:15 +0000 Date: Wed, 8 May 2024 21:51:15 -0700 From: Christoph Hellwig To: Hailong Liu Cc: Gao Xiang , akpm@linux-foundation.org, Michal Hocko , urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com, 21cnbao@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xiang@kernel.org, chao@kernel.org, Oven Subject: Re: [RFC PATCH] mm/vmalloc: fix vmalloc which may return null if called with __GFP_NOFAIL Message-ID: References: <20240508125808.28882-1-hailong.liu@oppo.com> <404add29-2d3f-45db-9103-0c5b66fb254e@linux.alibaba.com> <20240508144321.ymnhn54daaabalhe@oppo.com> <90a127e5-d884-44b5-bb76-773a7485c2f1@linux.alibaba.com> <20240508153136.x4rxildsgza234uv@oppo.com> <52f9e300-4ab9-43c1-abae-cbe3da27e5b0@linux.alibaba.com> <20240509013059.vegko7dlty7vppy5@oppo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240509013059.vegko7dlty7vppy5@oppo.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Stat-Signature: 1zuuajzhhnm6htrb3cdkznwjbmduhdbe X-Rspamd-Queue-Id: 50A641A0010 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1715230281-845094 X-HE-Meta: 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 1y0rmh4W Xw7isHaZBAu6axY2hl2l4LIFmjL15NA2qFb8FuFrcXvvWGdQMXGuTgeRk+eibqbCYYAttTSF34tg/ktOCZ06Dw4IdGonJZ5kiMsIAfOtDlqO6W696bhJDikBys1DdqCGJcg8NcuRPpUC4kgRQ0GscUL5Rzt54o61LwwwJxABsbq/sIjYqqp+iM1G1f1SPNaD5koLs+Y6zSd/dtR5MCZkGSyFjA5Rlz/vnRNfkqspvOI0KKERdql/JPdasHvMINijam4ZMZrL1TpcFLTsuysMqTKFCtvM/TxF5F0BVc1z1jGJIBXRsH8AQPHo0gZs75DnWcsuyz2/YOBiBpg6qH0B4MBbmOsEBNzW0eXD6TsBAQSUHkdIR8/0dt8YyvLsv3r/uGncA6qBm1vTrhX0z+qW6HcY9JL2Xk3CSKnoLZb+XhbE34s2AiaA8Yyd/eDDR/ym77V252gPb6aOgAQMBz5k7t7aW3VQIQeLAox5ULb1OH9j5pfU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, May 09, 2024 at 09:30:59AM +0800, Hailong Liu wrote: > I’m not suggesting that erofs would cause a memleak. What I mean is > that if kvmalloc is invoked with __GFP_NOFAIL, it must ensure a non-NULL > return, even in scenarios where memory leaks caused by other processes > result in the inability to allocate a page. In such a situation, it > should result in “Kernel panic - not syncing: System is deadlocked > on memory”. Yes. __GFP_NOFAIL is a contract that says never ever return NULL. The callers will generally not handle a NULL return and blindly dereference it, leading to all kinds of nasty security issues. Note that deadlocking would be nice, but at least it is just a denial of service and not a possible privilege escalation.