linux-kernel - [PATCH V2 0/2] arm64/mm: Enable batched TLB flush in unmap_hotplug

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Message-Id: <20260203130348.612150-1-anshuman.khandual@arm.com>
Date: Tue,  3 Feb 2026 13:03:46 +0000
From: Anshuman Khandual <anshuman.khandual@....com>
To: linux-arm-kernel@...ts.infradead.org
Cc: Anshuman Khandual <anshuman.khandual@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Yang Shi <yang@...amperecomputing.com>,
	Christoph Lameter <cl@...two.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH V2 0/2] arm64/mm: Enable batched TLB flush in unmap_hotplug_range()

This series enables batched TLB flush in unmap_hotplug_range() which avoids
individual page TLB flush for potential CONT blocks in linear mapping while
also improving performance due to range based TLB operation along with less
synchronization barrier instructions.

It also now rejects memory removal that might split a leaf entry in kernel
mapping, which would have otherwise required re-structuring using the break
before make (BBM) semantics. But kernel cannot tolerate BBM, so remapping to
fine grained leaves would not be possible on systems without BBML2_NOABORT.

This series applies on 6.19-rc8 and tested on KVM guest.

Changes in V2:

- Renamed split_kernel_leaf_boundary() as addr_splits_kernel_leaf()
- Dropped pte_valid()/pmd_leaf() before checking pte_cont()/pmd_cont()
- Changed and dropped variables in can_unmap_without_split()
- Moved can_unmap_without_split() after boot memory check
- Renamed 'prevent_bootmem' as 'prevent_memory' across the board
- Updated commit message in both patches

Changes in V1:

- https://lore.kernel.org/all/20260202042617.504183-1-anshuman.khandual@arm.com/

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Ryan Roberts <ryan.roberts@....com>
Cc: Yang Shi <yang@...amperecomputing.com>
Cc: Christoph Lameter <cl@...two.org>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org

Anshuman Khandual (2):
  arm64/mm: Enable batched TLB flush in unmap_hotplug_range()
  arm64/mm: Reject memory removal that splits a kernel leaf mapping

 arch/arm64/mm/mmu.c | 236 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 216 insertions(+), 20 deletions(-)

-- 
2.30.2