From: Will Deacon <will@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Andrew Morton <akpm@linux-foundation.org>,
Uladzislau Rezki <urezki@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
David Hildenbrand <david@redhat.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Alexandre Ghiti <alexghiti@rivosinc.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Ryan Roberts <ryan.roberts@arm.com>
Cc: kernel-team@android.com, Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64/mm: Permit lazy_mmu_mode to be nested
Date: Wed, 14 May 2025 16:14:12 +0100 [thread overview]
Message-ID: <174722572203.77262.3085803317219491344.b4-ty@kernel.org> (raw)
In-Reply-To: <20250512150333.5589-1-ryan.roberts@arm.com>
On Mon, 12 May 2025 16:03:31 +0100, Ryan Roberts wrote:
> lazy_mmu_mode is not supposed to permit nesting. But in practice this
> does happen with CONFIG_DEBUG_PAGEALLOC, where a page allocation inside
> a lazy_mmu_mode section (such as zap_pte_range()) will change
> permissions on the linear map with apply_to_page_range(), which
> re-enters lazy_mmu_mode (see stack trace below).
>
> The warning checking that nesting was not happening was previously being
> triggered due to this. So let's relax by removing the warning and
> tolerate nesting in the arm64 implementation. The first (inner) call to
> arch_leave_lazy_mmu_mode() will flush and clear the flag such that the
> remainder of the work in the outer nest behaves as if outside of lazy
> mmu mode. This is safe and keeps tracking simple.
>
> [...]
Applied to arm64 (for-next/mm), thanks!
[1/1] arm64/mm: Permit lazy_mmu_mode to be nested
https://git.kernel.org/arm64/c/1ef3095b1405
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
prev parent reply other threads:[~2025-05-14 15:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-12 15:03 Ryan Roberts
2025-05-12 18:55 ` Catalin Marinas
2025-05-14 15:14 ` Will Deacon [this message]
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