From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Dev Jain <dev.jain@arm.com>, lirongqing <lirongqing@baidu.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Yang Shi <yang@os.amperecomputing.com>,
Chaitanya S Prakash <chaitanyas.prakash@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: mm: refresh stale pmd snapshot after split_contpmd()
Date: Fri, 26 Jun 2026 18:03:39 +0200 [thread overview]
Message-ID: <f9f6bb59-e3f2-4201-888f-c56e83126934@kernel.org> (raw)
In-Reply-To: <e0031cbe-2a49-4611-ad48-bde73fe4cd1c@arm.com>
On 6/26/26 15:03, Dev Jain wrote:
>
>
> On 25/06/26 5:09 pm, lirongqing wrote:
>> From: Li RongQing <lirongqing@baidu.com>
>>
>> split_contpmd() modifies the pmd entries in-place by clearing the CONT
>> bit, but the local 'pmd' variable still holds the old snapshot with CONT
>> set. The subsequent split_pmd() call uses this stale value to derive the
>> pgprot for the new PTE entries via pmd_pgprot(), causing the resulting
>> PTEs to be populated with incorrect protection bits.
>
> Since the block was CONTPMD, it means the pgprot was uniform on that block,
> so after splitting, it should be safe to derive the pgprot from individual pmd's
> right?
I'm also confused by that, can we get some details why (and how) the cont bit
misguides pmd_pgprot?
--
Cheers,
David
next prev parent reply other threads:[~2026-06-26 16:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-25 11:39 [PATCH] arm64: mm: refresh stale pmd snapshot after split_contpmd() lirongqing
2026-06-26 13:03 ` Dev Jain
2026-06-26 16:03 ` David Hildenbrand (Arm) [this message]
2026-06-26 22:53 ` Yang Shi
2026-06-27 2:46 ` 答复: [外部邮件] " Li,Rongqing
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