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From: Muchun Song <muchun.song@linux.dev>
To: Dev Jain <dev.jain@arm.com>
Cc: osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org,
	david@kernel.org, liam@infradead.org, riel@surriel.com,
	vbabka@kernel.org, harry@kernel.org, jannh@google.com,
	lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, rcampbell@nvidia.com,
	apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com,
	joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com,
	gourry@gourry.net, ying.huang@linux.alibaba.com, mel@csn.ul.ie,
	nao.horiguchi@gmail.com, ak@linux.intel.com,
	j-nomura@ce.jp.nec.com, pfalcato@suse.de, dave.hansen@intel.com,
	tglx@kernel.org, jpoimboe@kernel.org, ryan.roberts@arm.com,
	anshuman.khandual@arm.com, stable@vger.kernel.org
Subject: Re: [PATCH 3/5] mm/migrate: use huge_ptep_get() in remove_migration_pte()
Date: Fri, 26 Jun 2026 11:32:03 +0800	[thread overview]
Message-ID: <7E9EBE58-C2D0-44F4-8797-D8077E26AFEC@linux.dev> (raw)
In-Reply-To: <20260625112955.3254283-4-dev.jain@arm.com>



> On Jun 25, 2026, at 19:29, Dev Jain <dev.jain@arm.com> wrote:
> 
> remove_migration_pte() converts migration entries back to present PTEs
> after folio migration completes. For hugetlb folios,
> page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in
> pvmw.pte, but the code reads it with ptep_get().
> 
> On arches which provide their own huge_ptep_get() to dereference a huge
> pte pointer, accessing via ptep_get() would cause pte_pfn(),
> pte_present() etc to misbehave.
> 
> It is not clear whether this has a trivially visible effect to userspace.

We are dealing with migration entries here, so the issue mentioned shouldn't
be a problem with any of the architectures. Semantically speaking, we definitely
should fix this.

> 
> Use huge_ptep_get() to dereference a huge pte pointer.
> 
> Fixes: 290408d4a250 ("hugetlb: hugepage migration core")
> Cc: stable@vger.kernel.org
> Signed-off-by: Dev Jain <dev.jain@arm.com>

Acked-by: Muchun Song <muchun.song@linux.dev>

Thanks



  reply	other threads:[~2026-06-26  3:33 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-25 11:29 [PATCH 0/5] Fix incorrect access of hugetlb pte entries Dev Jain
2026-06-25 11:29 ` [PATCH 1/5] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Dev Jain
2026-06-26  3:17   ` Muchun Song
2026-06-26  4:03     ` Dev Jain
2026-06-26  4:16       ` Muchun Song
2026-06-25 11:29 ` [PATCH 2/5] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Dev Jain
2026-06-26  3:24   ` Muchun Song
2026-06-25 11:29 ` [PATCH 3/5] mm/migrate: use huge_ptep_get() in remove_migration_pte() Dev Jain
2026-06-26  3:32   ` Muchun Song [this message]
2026-06-25 11:29 ` [PATCH 4/5] mm/page_vma_mapped: use huge_ptep_get() for hugetlb Dev Jain
2026-06-26  2:31   ` Lance Yang
2026-06-26  4:06     ` Dev Jain
2026-06-26  7:48   ` Lance Yang
2026-06-26  9:14     ` Lance Yang
2026-06-26 13:23     ` Dev Jain
2026-06-26 14:10       ` Lance Yang
2026-06-26 15:26         ` Dev Jain
2026-06-26 16:46           ` Lance Yang
2026-06-27  3:54             ` Miaohe Lin
2026-06-27  7:13             ` Dev Jain
2026-06-28  5:44               ` Lance Yang
2026-06-29  6:39                 ` David Hildenbrand (Arm)
2026-06-29  6:48                   ` Dev Jain
2026-06-29  7:25                     ` David Hildenbrand (Arm)
2026-06-29  7:48                       ` Lance Yang
2026-06-29  8:05                         ` David Hildenbrand (Arm)
2026-06-29  8:22                           ` Lance Yang
2026-06-30 11:34                           ` Dev Jain
2026-06-29  6:59                   ` Lance Yang
2026-06-25 11:29 ` [PATCH 5/5] mm/mprotect: " Dev Jain
2026-06-26  3:40   ` Muchun Song
2026-06-26  4:08     ` Dev Jain
2026-06-26  4:21       ` Muchun Song
2026-06-26  4:42         ` Dev Jain
2026-06-25 13:59 ` [PATCH 0/5] Fix incorrect access of hugetlb pte entries Zi Yan
2026-06-26  4:09   ` Dev Jain

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