From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> commit 4737edbbdd4958ae29ca6a310a6a2fa4e0684b01 upstream. split_huge_page_to_list() WARNs when called for huge zero pages, which sounds to me too harsh because it does not imply a kernel bug, but just notifies the event to admins. On the other hand, this is considered as critical by syzkaller and makes its testing less efficient, which seems to me harmful. So replace the VM_WARN_ON_ONCE_FOLIO with pr_warn_ratelimited. Link: https://lkml.kernel.org/r/20230406082004.2185420-1-naoya.horiguchi@xxxxxxxxx Fixes: 478d134e9506 ("mm/huge_memory: do not overkill when splitting huge_zero_page") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> Reported-by: syzbot+07a218429c8d19b1fb25@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/lkml/000000000000a6f34a05e6efcd01@xxxxxxxxxx/ Reviewed-by: Yang Shi <shy828301@xxxxxxxxx> Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Cc: Xu Yu <xuyu@xxxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2674,9 +2674,10 @@ int split_huge_page_to_list(struct page VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); is_hzp = is_huge_zero_page(&folio->page); - VM_WARN_ON_ONCE_FOLIO(is_hzp, folio); - if (is_hzp) + if (is_hzp) { + pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); return -EBUSY; + } if (folio_test_writeback(folio)) return -EBUSY;
