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 D4325C4332F for ; Tue, 18 Oct 2022 14:39:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 555EA6B0072; Tue, 18 Oct 2022 10:39:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 506096B0075; Tue, 18 Oct 2022 10:39:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3F46D6B0078; Tue, 18 Oct 2022 10:39:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 300336B0072 for ; Tue, 18 Oct 2022 10:39:41 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 06D321A10D3 for ; Tue, 18 Oct 2022 14:39:41 +0000 (UTC) X-FDA: 80034328962.25.C864021 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf25.hostedemail.com (Postfix) with ESMTP id D8EBBA002F for ; Tue, 18 Oct 2022 14:39:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=z6yxKpH3CxfuQtgoIMIZtd4wXwIYmAepPnY2ExrBrmY=; b=S7s0BHcTB5Z6UOFQKXnl4dWQtt hKdrTVnxrWlrHoFp5Jwt+u3vHG0QLX79hcQQVKX4VaqBaUja9r+dav153uB/VcSdwVxWQlBTOHgpX 9OvjBDsZSyX43tkrBWlWrDkjqACCC6EQ5RINuFwbQh2qgSzGrQyP/6EkUVJDF2mCuru6fI4fxy1NR 6Igp+kUuFgGkazUhiLJdHfstC1cGjdQNfYuiZrY114mM0cADm5wDRIQqym6TqeKSA/pi0DWen4qfl a6OFtosAWLHu5g/D9n3FZRMti5sSJ1B109isb03KVXGv0H/DW+CaxAuz6EKLR6GSnGgQV5rar3/5G yS5kaGnA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1oknkp-00Ao5S-3Z; Tue, 18 Oct 2022 14:39:39 +0000 Date: Tue, 18 Oct 2022 15:39:39 +0100 From: Matthew Wilcox To: Tuo Cao <91tuocao@gmail.com> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: folio-compat: fix bug for pagecache_get_page Message-ID: References: <20221018143639.5099-1-91tuocao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221018143639.5099-1-91tuocao@gmail.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666103980; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=z6yxKpH3CxfuQtgoIMIZtd4wXwIYmAepPnY2ExrBrmY=; b=V/jMHWL5o+qHwGg1xzz4M0YqGlR/3IYm+jnarLrIoUsnI0Q5ahpRg7i9ubyVt0CrNyKKac YXiq89JGbne/u8oOgcQrkVdGArv5A5u1vb0jdwcx5MfuucArqTXoOnFszgwaO4XbYZ46dr jNpW6LBUUucyY7wiF62Q5p+0xhCXuFM= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=S7s0BHcT; spf=none (imf25.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666103980; a=rsa-sha256; cv=none; b=M/WNSERo2pBYUYRGJt4cgO1f20G3RGu7JPbtOTaIhFvu2TqqCycy68oXDjDnz2X0K3IdiH 2XRbnUFE88SCCul3IwGHSy0ZzWu4ZBd/rJRObtHogkhO6vznsQPFcjTXcN1W7wgeKEf9L3 NKcqYs4N0+A4VKQyGfVPR4yR+nGlCVc= Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=S7s0BHcT; spf=none (imf25.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Stat-Signature: mjaujwe8dwcq9fruqncch75opuqq783f X-Rspamd-Queue-Id: D8EBBA002F X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1666103978-653913 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: On Tue, Oct 18, 2022 at 10:36:39PM +0800, Tuo Cao wrote: > The folio returned from __filemap_get_folio may be a NULL, it will > causes the kernel crash when access folio->page. This is not a bug. &folio->page does not dereference folio but performs pointer arithmetic.