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From: Dev Jain <dev.jain@arm.com>
To: Karim Manaouil <kmanaouil.dev@gmail.com>,
	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: akpm@linux-foundation.org, david@redhat.com,
	catalin.marinas@arm.com, will@kernel.org,
	Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org,
	surenb@google.com, mhocko@suse.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, suzuki.poulose@arm.com,
	steven.price@arm.com, gshan@redhat.com,
	linux-arm-kernel@lists.infradead.org,
	yang@os.amperecomputing.com, ryan.roberts@arm.com,
	anshuman.khandual@arm.com
Subject: Re: [PATCH v3 1/2] arm64: pageattr: Use pagewalk API to change memory permissions
Date: Thu, 19 Jun 2025 09:33:29 +0530	[thread overview]
Message-ID: <1c7ba21a-7038-4edf-8734-fdba0c617c52@arm.com> (raw)
In-Reply-To: <20250614145021.7yve56wcxf3dlvwg@ed.ac.uk>


On 14/06/25 8:20 pm, Karim Manaouil wrote:
> On Fri, Jun 13, 2025 at 05:27:27PM +0100, Lorenzo Stoakes wrote:
>> On Fri, Jun 13, 2025 at 07:13:51PM +0530, Dev Jain wrote:
>>> +		if (WARN_ON_ONCE((next - addr) != PGDIR_SIZE))
>>> +			return -EINVAL;
>> I guess the point here is to assert that the searched range _entirely
>> spans_ the folio that the higher order leaf page table entry describes.
>>
>> I'm guessing this is desired.
>>
>> But I'm not sure this should be a warning?
>>
>> What if you happen to walk a range that isn't aligned like this?
> My understandging is that the caller must ensure that addr is
> pud/pmd/pte-aligned. But, imho, since -EINVAL is returned, I don't think
> the WARN_ON_ONCE() is needed.

I don't really have a strong opinion on this. Ryan may be better fitted
to answer.

>

  reply	other threads:[~2025-06-19  4:04 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-13 13:43 [PATCH v3 0/2] Enable permission change on arm64 kernel block mappings Dev Jain
2025-06-13 13:43 ` [PATCH v3 1/2] arm64: pageattr: Use pagewalk API to change memory permissions Dev Jain
2025-06-13 16:27   ` Lorenzo Stoakes
2025-06-14 14:50     ` Karim Manaouil
2025-06-19  4:03       ` Dev Jain [this message]
2025-06-25 10:57         ` Ryan Roberts
2025-06-15  7:25     ` Mike Rapoport
2025-06-25 10:57       ` Ryan Roberts
2025-06-15  7:32   ` Mike Rapoport
2025-06-19  4:10     ` Dev Jain
2025-06-25 11:04     ` Ryan Roberts
2025-06-25 20:40       ` Yang Shi
2025-06-26  8:47         ` Ryan Roberts
2025-06-26 21:08           ` Yang Shi
2025-06-25 11:20   ` Ryan Roberts
2025-06-26  5:47   ` Dev Jain
2025-06-26  8:15     ` Ryan Roberts
2025-06-13 13:43 ` [PATCH v3 2/2] arm64: pageattr: Enable huge-vmalloc permission change Dev Jain
2025-06-25 11:08   ` Ryan Roberts
2025-06-25 11:16     ` Dev Jain

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