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Sun, 7 Apr 2024 13:56:23 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap2.dmz-prg2.suse.org with ESMTPSA id 4Kg+JQemEmbyGgAAn2gu4w (envelope-from ); Sun, 07 Apr 2024 13:56:23 +0000 Date: Sun, 7 Apr 2024 15:56:17 +0200 From: Oscar Salvador To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Miaohe Lin , David Hildenbrand , Peter Xu , stable@vger.kernel.org, Tony Luck Subject: Re: [PATCH] mm,swapops: Update check in is_pfn_swap_entry for hwpoison entries Message-ID: References: <20240407130537.16977-1-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240407130537.16977-1-osalvador@suse.de> X-Rspam-User: X-Stat-Signature: nicuske43o4a5jt38y8yqzqtc1ei5fyf X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DCF9CA0003 X-HE-Tag: 1712498186-35020 X-HE-Meta: U2FsdGVkX19nK7BUvRjl9UkPyWvjguBmtcyo+1NUxzJdZEDqAWjgdXpX4uIocjWhAyJQ8tBfILf9QyTjYtjq+V/7fvF+e8E3HF5xLsGENrZLbGQaF9W7+y7Ae2lvXwADnUSRNGz19lUcEUGjTdLyBzj06MV5fbAjx0d6C7FyeGpSH1eYzc7oY+zevXpGKKrySJfTZ6v9g8AbTIqHU1cupPKjkFhr6Bx7sc50h7nCUwzPECjRnMPC3z59bY6itWgWPiT3F8sRJxcsDZQU5B5x6N4rv0hHcGILQo6MU4Bt9w+HziFo7vKy/NL2Gh8gbVyLEup8nB513oE9VPJ1CTMCPTeJv/Qox4xR/1etvQd3dJGQLz2Tg82i8XHYw0WiSPZfik/lrB5BZShn8+x2XnbVBoxYa3Z5YvQo4bAPJ/FNbDv6dJk+dn2gpXFFCeGC3paBY9lDVSw84AC6ycsCbq3rruSJXFWi0dbYUOlztb8+gJ0rrsyHrvgaztEbxnfdc/lkre/b1tMqxkEhnuj4W9bm5nh0CVh4lVLgNJrOdeGQu/ZrAti2d904GHrNMOL692Zq3ZV+N6EztWCrPwmwpj3IJrp4oiL9Gs39dEPvHQgydPa5asQ7Sb5jT1CBL9pO/tfEhwLPEEgoQpiVhh+wyPBQXADgkv1dHbc5u0xd0wrF/dOj4i3z5KtWSJ17rcpk2gT3Aj5cURoccGrzN8kjJ68iy/41RHyPnayHXOKyXoitSBkEhCJtuAl+Spjfqx38alaxaXGmqUNMa7h3dWkZVHVjTR8GMz7nL5FNHupN2MdApS/FN304wZp5vDgdh/t4arBlIiXTrhfdEA078S5mEUbBM1tOvjBOQraQ6q13j8VQSaKRQNakA/lz/UBQAVJsNvO1UP1UukSAi0OOwfB20K4FgD1qHvQCraYgqS9P4cAnbA8JCg7vd1uKN2ZpkbjoK9j18GglD1asVjjnflB5t9I fM5AY3mC 6a58RvY3wXtnACHRQM0LvRM85NsAWuR2Djwf8Hmtd3/dqIfn3liOBZj7cOVN2QEPkoyFiRfNjk4hetaVHdaA9ZDv4z+TDazGs9ERrPazVnnExi+RKhxmth1c/FFyj25pd9mFkDPFUg3MSlg04XQqmIoL8PF90hr4dqz8Gxx/u4PCfcVmTEfVwt9a2Tp6d2x83L4gmx5N6OF0rT8ZKD9tdUOg5gaSCatSaKK9l9PMPCptygQiPnNdVmALjjYFNo60ZHFGXwS6gx0EBOZm9HCVvqedC3LY0rwn3Da8A0xcKBOAiHAOyicQPw4TahO0udH6dx3/mvuGB2ok7PfM= 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 Sun, Apr 07, 2024 at 03:05:37PM +0200, Oscar Salvador wrote: > Tony reported that the Machine check recovery was broken in v6.9-rc1, > as he was hitting a VM_BUG_ON when injecting uncorrectable memory errors > to DRAM. > After some more digging and debugging on his side, he realized that this > went back to v6.1, with the introduction of 'commit 0d206b5d2e0d ("mm/swap: add > swp_offset_pfn() to fetch PFN from swap entry")'. > That commit, among other things, introduced swp_offset_pfn(), replacing > hwpoison_entry_to_pfn() in its favour. > > The patch also introduced a VM_BUG_ON() check for is_pfn_swap_entry(), > but is_pfn_swap_entry() never got updated to cover hwpoison entries, which > means that we would hit the VM_BUG_ON whenever we would call > swp_offset_pfn() for such entries on environments with CONFIG_DEBUG_VM set. > Fix this by updating the check to cover hwpoison entries as well, and update > the comment while we are it. > > Reported-by: Tony Luck > Closes: https://lore.kernel.org/all/Zg8kLSl2yAlA3o5D@agluck-desk3/ > Tested-by: Tony Luck > Fixes: 0d206b5d2e0d ("mm/swap: add swp_offset_pfn() to fetch PFN from swap entry") > Cc: # 6.1.x I think I need to clarify why the stable. It is my understanding that some distros ship their kernel with CONFIG_DEBUG_VM set by default (I think Fedora comes to my mind?). I am fine with backing down if people think that this is an overreaction. -- Oscar Salvador SUSE Labs