linux-kernel - Re: [PATCH v6] arm64: Enable vmalloc-huge with ptdump

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Message-Id: <175853832495.3123711.10100627692023962115.b4-ty@kernel.org>
Date: Mon, 22 Sep 2025 14:14:46 +0100
From: Will Deacon <will@...nel.org>
To: catalin.marinas@....com,
	Dev Jain <dev.jain@....com>
Cc: kernel-team@...roid.com,
	Will Deacon <will@...nel.org>,
	anshuman.khandual@....com,
	quic_zhenhuah@...cinc.com,
	ryan.roberts@....com,
	kevin.brodsky@....com,
	yangyicong@...ilicon.com,
	joey.gouly@....com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	david@...hat.com,
	mark.rutland@....com,
	urezki@...il.com,
	jthoughton@...gle.com
Subject: Re: [PATCH v6] arm64: Enable vmalloc-huge with ptdump

On Mon, 22 Sep 2025 12:11:26 +0530, Dev Jain wrote:
> Our goal is to move towards enabling vmalloc-huge by default on arm64 so
> as to reduce TLB pressure. Therefore, we need a way to analyze the portion
> of block mappings in vmalloc space we can get on a production system; this
> can be done through ptdump, but currently we disable vmalloc-huge if
> CONFIG_PTDUMP_DEBUGFS is on. The reason is that lazy freeing of kernel
> pagetables via vmap_try_huge_pxd() may race with ptdump, so ptdump
> may dereference a bogus address.
> 
> [...]

Applied to arm64 (for-next/mm), thanks!

[1/1] arm64: Enable vmalloc-huge with ptdump
      https://git.kernel.org/arm64/c/fa93b45fd397

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev