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Thu, 6 May 2021 17:38:00 +0800 (HKT) Received: from alex-virtual-machine (10.88.1.103) by KSBJMAIL4.kingsoft.cn (10.88.1.79) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 6 May 2021 17:37:58 +0800 Date: Thu, 6 May 2021 17:37:57 +0800 From: Aili Yao To: Naoya Horiguchi CC: , Tony Luck , Andrew Morton , Oscar Salvador , "David Hildenbrand" , Borislav Petkov , "Andy Lutomirski" , Naoya Horiguchi , Jue Wang , , Subject: Re: [PATCH v4 1/2] mm/memory-failure: Use a mutex to avoid memory_failure() races Message-ID: <20210506173757.586580bd@alex-virtual-machine> In-Reply-To: <20210427062953.2080293-2-nao.horiguchi@gmail.com> References: <20210427062953.2080293-1-nao.horiguchi@gmail.com> <20210427062953.2080293-2-nao.horiguchi@gmail.com> Organization: kingsoft X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.88.1.103] X-ClientProxiedBy: KSBJMAIL1.kingsoft.cn (10.88.1.31) To KSBJMAIL4.kingsoft.cn (10.88.1.79) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprMIsWRmVeSWpSXmKPExsXCFcHor/tjx+QEg2U3mS3mrF/DZvF5wz82 i6/rfzFb3LxlYnF51xw2i3tr/rNanN+1ltVi1bw7zBYXGw8wWpyZVmTx5sI9FotnrVdZHHg8 vrf2sXjsnHWX3WPBplKPxXteMnlsWtXJ5rHp0yR2jxMzfrN4vLi6kcXj/b6rbB6bT1d7fN4k F8AdxWWTkpqTWZZapG+XwJVxs/8SW8EGjoolNwwbGO+zdTFycEgImEg8euzaxcjFISQwnUni 0LUt7BDOM0aJ95OuMXcxcnKwCKhILF13lQXEZhNQldh1bxYriC0ioCsxYVsvI0gDs8A/JolJ Vw8wgSSEBWIkdrzYxwhi8wpYSay6cBmsgVPAXqJh/SGwQUICxRLr7s0Cq+EXEJPovfKfCeIi e4nH6xUhWgUlTs58AlbOLKAjcWLVMWYIW15i+9s5zBBjFCUOL/nFDmJLAMXv/p7OCGHHSjQd uMU2gVF4FpJRs5CMmoVk1AJG5lWMLMW56YabGCHxFr6DcV7TR71DjEwcjIcYJTiYlUR4Ty+a nCDEm5JYWZValB9fVJqTWnyIUZqDRUmct3EmUEogPbEkNTs1tSC1CCbLxMEp1cBUZbvVJ99r n4ThOy4mn/e2fWu3dxpECWcFPfi6bndBDPuW+nwRPlHeX7PS5abv/jvnnPfW/lt3F8TdP+v8 /V4UM9/0PzqrtnYI3Dly9/yEe4t5I0pYlHdaS+mwxjZOcW1dKTol/RKPVui5Y/tr+B9NfnOM QX7v+5f/ty4v9RBz6Pbr3u2TMWVjx46K1WGRYp9er07c8IQ1ZTLjkxUfvT13s+tvNrtj2Cn5 T7Ut9aDBhOh2Tk+dG7tn7bwn+ThW7sSPlpJrrcsCV9dF7i09lS2wOOvewjVFpzsXFztfWln2 6vXJX5VVeVdePN4Y83St5dfqvq2fip1yZz2TNjEOjTZctq7Bf4mU5zdPC2H+CpWtSizFGYmG WsxFxYkAVOlEXCYDAAA= X-Rspamd-Queue-Id: 5EE40500152F Authentication-Results: imf01.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf01.hostedemail.com: domain of yaoaili@kingsoft.com designates 114.255.44.145 as permitted sender) smtp.mailfrom=yaoaili@kingsoft.com X-Rspamd-Server: rspam04 X-Stat-Signature: 44yd683o5tgwxorz99pjaapgf1n9s5j4 Received-SPF: none (kingsoft.com>: No applicable sender policy available) receiver=imf01; identity=mailfrom; envelope-from=""; helo=mail.kingsoft.com; client-ip=114.255.44.145 X-HE-DKIM-Result: none/none X-HE-Tag: 1620293881-655499 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, 27 Apr 2021 15:29:52 +0900 Naoya Horiguchi wrote: > From: Tony Luck > > There can be races when multiple CPUs consume poison from the same > page. The first into memory_failure() atomically sets the HWPoison > page flag and begins hunting for tasks that map this page. Eventually > it invalidates those mappings and may send a SIGBUS to the affected > tasks. > > But while all that work is going on, other CPUs see a "success" > return code from memory_failure() and so they believe the error > has been handled and continue executing. > > Fix by wrapping most of the internal parts of memory_failure() in > a mutex. > > Signed-off-by: Tony Luck > Signed-off-by: Naoya Horiguchi > Reviewed-by: Borislav Petkov Sorry to interrupt, I just thought one thing: This mutex seems not been bind to the error page, will there be some core case like test code or multi-poison case whick will break this mutex? Thanks! Aili Yao