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Wed, 8 May 2024 12:06:11 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id LKroNrNqO2b5UwAAD6G6ig (envelope-from ); Wed, 08 May 2024 12:06:11 +0000 Date: Wed, 8 May 2024 14:06:02 +0200 From: Oscar Salvador To: Jane Chu Cc: linmiaohe@huawei.com, nao.horiguchi@gmail.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] mm/memory-failure: try to send SIGBUS even if unmap failed Message-ID: References: <20240501232458.3919593-1-jane.chu@oracle.com> <20240501232458.3919593-2-jane.chu@oracle.com> <2f965887-19b5-47bf-98ca-d40b3ec05e75@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2f965887-19b5-47bf-98ca-d40b3ec05e75@oracle.com> X-Rspamd-Action: no action X-Stat-Signature: bs7ori4aetpi1fehmfkdprc194roimi1 X-Rspamd-Queue-Id: 19379140007 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1715169973-891386 X-HE-Meta: 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 7zdu9R+Y VwpBqPkS3kgdHD1W4WgMA3+FZ8usmKAZcXI9tAeuCqlZ3icSlcj4jxvW3ZlnxJgJi38rlke4vloCUrqn1FO5iuvC8iGeaw6Vk9cL/+DdS/H5n3OvRCuErVWXuRLyf6/OMDepLx9/GPFrm70Ui79cJbc/TbUW9NuQ6pi652A6EMh4UOhwnWQzhXTVJeeMpHJiqxl+AjQwRKv9Tg7DS22vtqmk7Nl02NgpDiwBGcePVQZsu5rUYnzVpYc+w91LEIeFFQtOABCPfnAQrPLuDI9hOfpkGgrYDJwweDEd5Q1ZrClKoQ5o= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000011, 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 Tue, May 07, 2024 at 10:54:10AM -0700, Jane Chu wrote: > I actually managed to hit the re-access case with an older version of Linux > - > > MCE occurred, but unmap failed,  no SIGBUS and test process re-access > > the same address over and over (hence MCE after MCE), as the CPU > > was unable to make forward progress.   In reality, this issue is fixed with > > kill_accessing_processes().  The comment for this patch refers to comment > made So we get a faulty page and we try to unmap it from all processes that might have it mapped in their pgtables. Prior to this patch we would kill the processes right away and now we deliver a SIGBUS. Seems safe as upon-reaccesing kill_accessing_process() will be called for already hwpoisoned pages. I think the changelog could be made more explicit about this scenario and state the role of kill_accessing_process more clear. With that: Reviewed-by: Oscar Salvador -- Oscar Salvador SUSE Labs