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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , "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, linmiaohe@huawei.com, david@redhat.com, jane.chu@oracle.com References: <20251023030521.473097-1-ziy@nvidia.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: <20251023030521.473097-1-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 566D0140008 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: sseom3sbpsd5bs1cg8dgr6s1swpjmhcg X-HE-Tag: 1761294711-810458 X-HE-Meta: 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 0WgFHoJG WLNn5dLTov4LYrnSIzji+uZ70C6jhuATYuKHiVorta2wzwtxBPw+XoSTzDITkLQwMLKoUowyg6T6lZ98sqgkh3cHCeBgH+wpCuaBVNAAlnkoKfHW+1VA449z8xhnQN7RFM4FTZzlvvCDaIeU5uZ5f5/MiTKQewnRB5X01DQ9mqKJnuwU03Vlf2qRuc6w13GA/Mfat4tdch3je5osB/FN3ZdOtzps2pD4Hj0z4wrrBGY24YXtEPer6EHbdPR+s/CRw9wjFaIRRNdT2v2gkHw+hTrabzeEt5KbFU3qmjqfi+u49Hx9lONr5aTQcCX69RqpuOFdGeJPuq3CGPCbyEp68bOu1HZyJYDRFSEpcCtJkrRvj/7o= 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 > --- Good spot! LGTM, feel free to add: Reviewed-by: Lance Yang