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 3BC20C433EF for ; Tue, 19 Apr 2022 04:09:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A212E6B00B5; Tue, 19 Apr 2022 00:09:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A8EF6B00B6; Tue, 19 Apr 2022 00:09:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 849D76B00B8; Tue, 19 Apr 2022 00:09:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id 704BF6B00B5 for ; Tue, 19 Apr 2022 00:09:54 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 3A6CC205AE for ; Tue, 19 Apr 2022 04:09:54 +0000 (UTC) X-FDA: 79372300308.21.96C8DCE Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf22.hostedemail.com (Postfix) with ESMTP id 7EF6EC000C for ; Tue, 19 Apr 2022 04:09:53 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DB3CD61157; Tue, 19 Apr 2022 04:09:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFCD0C385A7; Tue, 19 Apr 2022 04:09:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1650341392; bh=pMG4gBqrjUuaVREf5Do0t2y3IdtKoqfe6hpp7ubRJWQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=zXGb7uOHZhmcOCQpI+rMPu2asgr1XvhwF+5kGkjBB9d2riSOtt5vxSmlTb+Iw2CD3 p5ZpiVp1gSg1az5NTQwch04E1VEF5dPXdHnve00QJ8PyW9pGABo20K1oCVUkZlDu8z xLziZtxICmzhR/k3eaoIOb3qDkn7gMhNLuyhtl2A= Date: Mon, 18 Apr 2022 21:09:51 -0700 From: Andrew Morton To: Miaohe Lin Cc: , , , , , Subject: Re: [PATCH] mm/madvise: fix potential pte_unmap_unlock pte error Message-Id: <20220418210951.b87743ae8b7c01f883e571ea@linux-foundation.org> In-Reply-To: <20220416081416.23304-1-linmiaohe@huawei.com> References: <20220416081416.23304-1-linmiaohe@huawei.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=zXGb7uOH; dmarc=none; spf=pass (imf22.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7EF6EC000C X-Stat-Signature: bdeocuh58jhuydiwsbzxnaomxc873xhz X-HE-Tag: 1650341393-559164 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 Sat, 16 Apr 2022 16:14:16 +0800 Miaohe Lin wrote: > We can't assume pte_offset_map_lock will return same orig_pte value. So > it's necessary to reacquire the orig_pte or pte_unmap_unlock will unmap > the stale pte. hm, where did you learn this info about pte_offset_map_lock()? I assume this is from code inspection only? No observed runtime failures?