Re: [PATCH] tlb: hugetlb: Add arm64 contiguous hint awareness

From: Catalin Marinas <catalin.marinas@arm.com>
To: Steve Capper <steve.capper@arm.com>
Cc: linux-mm@kvack.org, David Hildenbrand <david@redhat.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] tlb: hugetlb: Add arm64 contiguous hint awareness
Date: Wed, 23 Mar 2022 18:30:43 +0000	[thread overview]
Message-ID: <YjtnU0JGGEmJwPqH@arm.com> (raw)
In-Reply-To: <20220323165218.35499-1-steve.capper@arm.com>

On Wed, Mar 23, 2022 at 04:52:18PM +0000, 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 the ability to define per-arch implementations of
> tlb_remove_huge_tlb_entry and supplies an arm64 implementation that
> covers the contiguous hint sizes.
> 
> Reported-by: David Hildenbrand <david@redhat.com>
> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Peter Zijlstra (Intel) <peterz@infradead.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>