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* FAILED: patch "[PATCH] mm/migrate: use huge_ptep_get() in remove_migration_pte()" failed to apply to 6.6-stable tree
@ 2026-09-03 10:48 gregkh
  2026-09-03 19:00 ` [PATCH 6.6.y 1/2] mm/rmap: integrate PMD-mapped folio splitting into pagewalk loop Sasha Levin
  0 siblings, 1 reply; 3+ messages in thread
From: gregkh @ 2026-09-03 10:48 UTC (permalink / raw)
  To: dev.jain, ak, akpm, anshuman.khandual, apopple, byungchul,
	catalin.marinas, dave.hansen, david, gourry, harry, j-nomura,
	jannh, joshua.hahnjy, jpoimboe, kas, lance.yang, liam, ljs,
	matthew.brost, mel, muchun.song, nao.horiguchi, osalvador,
	pfalcato, rakie.kim, rcampbell, riel, ryan.roberts, stable,
	vbabka, will, ying.huang, ziy
  Cc: stable


The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x ac1ec50d71b953524100ddc09057ee61a3dfaff3
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090332-posh-plaster-8398@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ac1ec50d71b953524100ddc09057ee61a3dfaff3 Mon Sep 17 00:00:00 2001
From: Dev Jain <dev.jain@arm.com>
Date: Fri, 3 Jul 2026 11:41:57 +0000
Subject: [PATCH] mm/migrate: use huge_ptep_get() in remove_migration_pte()

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.

Use huge_ptep_get() to dereference a huge pte pointer.

Link: https://lore.kernel.org/20260703114202.365553-5-dev.jain@arm.com
Fixes: 290408d4a250 ("hugetlb: hugepage migration core")
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Jun'ichi "Nick" Nomura <j-nomura@ce.jp.nec.com>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 1977905ce12c..b6f56b67e367 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -372,7 +372,11 @@ static bool remove_migration_pte(struct folio *folio,
 			continue;
 		}
 #endif
-		old_pte = ptep_get(pvmw.pte);
+		if (folio_test_hugetlb(folio))
+			old_pte = huge_ptep_get(vma->vm_mm, pvmw.address,
+						pvmw.pte);
+		else
+			old_pte = ptep_get(pvmw.pte);
 		if (rmap_walk_arg->map_unused_to_zeropage &&
 		    try_to_map_unused_to_zeropage(&pvmw, folio, old_pte, idx))
 			continue;


^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-03 19:00 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2026-09-03 10:48 FAILED: patch "[PATCH] mm/migrate: use huge_ptep_get() in remove_migration_pte()" failed to apply to 6.6-stable tree gregkh
2026-09-03 19:00 ` [PATCH 6.6.y 1/2] mm/rmap: integrate PMD-mapped folio splitting into pagewalk loop Sasha Levin
2026-09-03 19:00   ` [PATCH 6.6.y 2/2] mm/migrate: use huge_ptep_get() in remove_migration_pte() Sasha Levin

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