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Content-Language: en-US To: Zi Yan Cc: akpm@linux-foundation.org, syzkaller-bugs@googlegroups.com, mcgrof@kernel.org, nao.horiguchi@gmail.com, Lorenzo Stoakes , kernel@pankajraghav.com, Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , jane.chu@oracle.com, Dev Jain , Barry Song , "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, david@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linmiaohe@huawei.com, syzbot+e6367ea2fdab6ed46056@syzkaller.appspotmail.com References: <20251010173906.3128789-1-ziy@nvidia.com> <20251010173906.3128789-2-ziy@nvidia.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: <20251010173906.3128789-2-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam05 X-Stat-Signature: 5qn13ybxiw7kdtiqex3sbtuyzqca7d7i X-Rspam-User: X-Rspamd-Queue-Id: 8D2C316000A X-HE-Tag: 1760149568-704954 X-HE-Meta: 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 puRFc4HY crfkY1a7ZOT1EYG+dk06shaG8qj2nL/wgcXn8EHdVj9sjN5I= 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 2025/10/11 01:39, Zi Yan wrote: > Page cache folios from a file system that support large block size (LBS) > can have minimal folio order greater than 0, thus a high order folio might > not be able to be split down to order-0. Commit e220917fa507 ("mm: split a > folio in minimum folio order chunks") bumps the target order of > split_huge_page*() to the minimum allowed order when splitting a LBS folio. > This causes confusion for some split_huge_page*() callers like memory > failure handling code, since they expect after-split folios all have > order-0 when split succeeds but in really get min_order_for_split() order > folios. > > Fix it by failing a split if the folio cannot be split to the target order. > > Fixes: e220917fa507 ("mm: split a folio in minimum folio order chunks") > [The test poisons LBS folios, which cannot be split to order-0 folios, and > also tries to poison all memory. The non split LBS folios take more memory > than the test anticipated, leading to OOM. The patch fixed the kernel > warning and the test needs some change to avoid OOM.] > Reported-by: syzbot+e6367ea2fdab6ed46056@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/68d2c943.a70a0220.1b52b.02b3.GAE@google.com/ > Signed-off-by: Zi Yan > --- > include/linux/huge_mm.h | 28 +++++----------------------- > mm/huge_memory.c | 9 +-------- > mm/truncate.c | 6 ++++-- > 3 files changed, 10 insertions(+), 33 deletions(-) > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > index 8eec7a2a977b..9950cda1526a 100644 > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -394,34 +394,16 @@ static inline int split_huge_page_to_list_to_order(struct page *page, struct lis > * Return: 0: split is successful, otherwise split failed. > */ > static inline int try_folio_split(struct folio *folio, struct page *page, > - struct list_head *list) > + struct list_head *list, unsigned int order) Seems like we need to add the order parameter to the stub for try_folio_split() as well? #ifdef CONFIG_TRANSPARENT_HUGEPAGE ... #else /* CONFIG_TRANSPARENT_HUGEPAGE */ static inline int try_folio_split(struct folio *folio, struct page *page, struct list_head *list) { VM_WARN_ON_ONCE_FOLIO(1, folio); return -EINVAL; } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ Cheers, Lance