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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , "Matthew Wilcox (Oracle)" , Wei Yang , Yang Shi , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org References: <20251023030521.473097-1-ziy@nvidia.com> From: Baolin Wang In-Reply-To: <20251023030521.473097-1-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: j3hk48fcro5ea1ntp4nh1rqu98y3y9u6 X-Rspamd-Queue-Id: 6FCE9140005 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1761271717-846451 X-HE-Meta: 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 y5k8v8PA LzP+Bak7kBp0WwnRgavXjdTrILWc111Z5PQKagJJ3SQd25oqUYJ8Ro9hgiVhTiLoL/Udpm93EBXTrB/WWnqMMGCeqEPXOnEx+Mw/I2fvbGYTeTqbf2eZGVxBSjepbjKDskJse9KNZ6aiXV3+V6VfvmMVne03Lbg9rZ2hQzI821jI2W9wBqEAspVbkqliaci3Rou5yY7BlUK+CifCBcZsM8mZdJIotbDdxtWUOXlvM7XmId9yzPmdXeDOvC6HdLGVnhAMnD/NT9hSwloI5pDUH6GjYKxg3y4eFKIUe3yPFa4us1D44NKuMTsCahIn2klqlm4TIYcat1YubmA6DHXzW2V3lnH0x7smvmWFM22u7Ikjk27p2cEG+4iJhG0WjOkc44TkRvH/f79UMyGR5yF0vVXn/U0PzJgYmKPr159Ky9Gq45vEfv7cfUjd9AIrABlHQvFMV 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 2025/10/23 11:05, Zi Yan wrote: > folio split clears PG_has_hwpoisoned, but the flag should be preserved in > after-split folios containing pages with PG_hwpoisoned flag if the folio is > split to >0 order folios. Scan all pages in a to-be-split folio to > determine which after-split folios need the flag. > > An alternatives is to change PG_has_hwpoisoned to PG_maybe_hwpoisoned to > avoid the scan and set it on all after-split folios, but resulting false > positive has undesirable negative impact. To remove false positive, caller > of folio_test_has_hwpoisoned() and folio_contain_hwpoisoned_page() needs to > do the scan. That might be causing a hassle for current and future callers > and more costly than doing the scan in the split code. More details are > discussed in [1]. > > This issue can be exposed via: > 1. splitting a has_hwpoisoned folio to >0 order from debugfs interface; > 2. truncating part of a has_hwpoisoned folio in > truncate_inode_partial_folio(). > > And later accesses to a hwpoisoned page could be possible due to the > missing has_hwpoisoned folio flag. This will lead to MCE errors. > > Link: https://lore.kernel.org/all/CAHbLzkoOZm0PXxE9qwtF4gKR=cpRXrSrJ9V9Pm2DJexs985q4g@mail.gmail.com/ [1] > Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages") > Cc: stable@vger.kernel.org > Signed-off-by: Zi Yan > --- LGTM. Reviewed-by: Baolin Wang