On 7/19/21 6:31 PM, Gavin Shan wrote:
>> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
>> + has_transparent_hugepage()) {
>> + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER);
>> + if (page) {
>> + args->pmd_pfn = page_to_pfn(page);
>> + args->pte_pfn = args->pmd_pfn;
>> + return 0;
>> + }
>> + }
>> +
>
> As syzbot reported against v1 series, we could allocate pages larger than (1 << (MAX_ORDER - 1)) here.
> So __GFP_NOWARN is needed here. I will fix it in v3 series.
I could find the following build error reported from lkp on V2.
mm/debug_vm_pgtable.c:445:8: warning: variable 'pud' set but not used [-Wunused-but-set-variable]
Could you please point to the syzbot reported problem on V1 as you
have mentioned above. Are there configs where HPAGE_[PMD|PUD]_ORDER
is greater than (MAX_ORDER - 1) ? If yes, how adding __GFP_NOWARN
solves the problem ?
