Re: [PATCH v2 01/12] mm/debug_vm_pgtable: Introduce struct pgtable_debug_args
From: Anshuman Khandual <hidden>
Date: 2021-07-20 06:42:30
Also in:
lkml
On 7/19/21 6:31 PM, Gavin Shan wrote:
quoted
+ 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 ?