On 17.10.25 03:36, 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 reality get min_order_for_split() order folios and give warnings.
Fix it by failing a split if the folio cannot be split to the target order. Rename try_folio_split() to try_folio_split_to_order() to reflect the added new_order parameter. Remove its unused list parameter.
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/ Cc: stable@vger.kernel.org Signed-off-by: Zi Yan ziy@nvidia.com Reviewed-by: Luis Chamberlain mcgrof@kernel.org Reviewed-by: Pankaj Raghav p.raghav@samsung.com Reviewed-by: Wei Yang richard.weiyang@gmail.com
With Lorenzos comments addressed, this looks good to me, thanks for taking care of this!
Acked-by: David Hildenbrand david@redhat.com