Re: [PATCH] arm64/mm: Optimize TLB flush in unmap_hotplug_[pmd|pud]_range()

[Catalin Marinas]

On Fri, Jun 26, 2026 at 02:28:45AM +0100, Anshuman Khandual wrote:
> flush_tlb_kernel_range() could flush down an entire block mapping just with
> a single PAGE_SIZE stride. This capability was being used umapping PMD and
> PUD based block mappings in unmap_hotplug_[pmd|pud]_range().
> 
> But later on the commit 48478b9f7913
> ("arm64/mm: Enable batched TLB flush in unmap_hotplug_range()") replaced
> this PAGE_SIZE stride with [PMD|PUD]_SIZE strides, hence forcing multiple
> PAGE_SIZE stride based TLB flushes on platforms where TLB range operation
> is not supported. Revert back to the earlier TLB behaviour along with the
> required comments that were dropped earlier.
> 
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/b0d5836032ce3135bfc473f6bff791306d086925.camel@xxxxxxxxxxxxxxx/
> Fixes: 48478b9f7913 ("arm64/mm: Enable batched TLB flush in unmap_hotplug_range()")
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>

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