Re: [PATCH v2] tlb: hugetlb: Add more sizes to tlb_remove_huge_tlb_entry

[Catalin Marinas <catalin.marinas@arm.com>]

On Wed, Mar 30, 2022 at 12:25:43PM +0100, Steve Capper wrote:
> tlb_remove_huge_tlb_entry only considers PMD_SIZE and PUD_SIZE when
> updating the mmu_gather structure.
> 
> Unfortunately on arm64 there are two additional huge page sizes that
> need to be covered: CONT_PTE_SIZE and CONT_PMD_SIZE. Where an end-user
> attempts to employ contiguous huge pages, a VM_BUG_ON can be experienced
> due to the fact that the tlb structure hasn't been correctly updated by
> the relevant tlb_flush_p.._range() call from tlb_remove_huge_tlb_entry.
> 
> This patch adds inequality logic to the generic implementation of
> tlb_remove_huge_tlb_entry s.t. CONT_PTE_SIZE and CONT_PMD_SIZE are
> effectively covered on arm64. Also, as well as ptes, pmds and puds;
> p4ds are now considered too.
> 
> Reported-by: David Hildenbrand <david@redhat.com>
> Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Link: https://lore.kernel.org/linux-mm/811c5c8e-b3a2-85d2-049c-717f17c3a03a@redhat.com/
> Signed-off-by: Steve Capper <steve.capper@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>