From: Karl Mehltretter <kmehltretter@gmail.com>
To: Dev Jain <dev.jain@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Anshuman Khandual <anshuman.khandual@arm.com>,
Ryan Roberts <ryan.roberts@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Muchun Song <muchun.song@linux.dev>,
Oscar Salvador <osalvador@suse.de>,
David Hildenbrand <david@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: hugetlb: fix BBM for mprotect() on contiguous PTEs
Date: Wed, 2 Sep 2026 19:06:56 +0200 [thread overview]
Message-ID: <aphV0wtGqn_EJHjB@gmail.com> (raw)
In-Reply-To: <551663b9-d031-4755-af7f-dc6c22524b35@arm.com>
On Wed, Sep 02, 2026 at 08:16:36PM +0100, Dev Jain wrote:
> Upon discussing with Ryan I got to know, he was implementing the
> contpte stuff for non-hugetlb user mappings and that basically
> drove a clarification on the semantics of contiguous bit and
> this rule was added.
>
> If you see currently for non-hugetlb mprotect() we do not flush
> during contpte teardown.
>
> So if the above reasoning makes sense, I can infact audit and
> remove the flushes in the hugetlb helpers.
>
Well, that's quite a turn of events! I wasn't aware of R_JQQTC or the
architectural clarification behind contpte_wrprotect_ptes().
My QEMU checker was based on the older assumption in commit
410982303772 and the existing hugetlb comments, so it treated a
clear and remake without an intermediate TLBI as a violation.
So... Please consider this patch withdrawn.
It's good that this may have uncovered an opportunity to remove
the flushes in the hugetlb helpers.
Thanks,
Karl
next prev parent reply other threads:[~2026-09-02 17:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 13:18 [PATCH] arm64: hugetlb: fix BBM for mprotect() on contiguous PTEs Karl Mehltretter
2026-09-02 4:38 ` Anshuman Khandual
2026-09-02 16:58 ` Karl Mehltretter
2026-09-02 14:46 ` Dev Jain
2026-09-02 16:16 ` Ryan Roberts
2026-09-02 17:06 ` Karl Mehltretter [this message]
2026-09-03 10:45 ` Will Deacon
2026-09-04 10:56 ` Ryan Roberts
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