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* FAILED: patch "[PATCH] mm/rmap: use huge_ptep_get() in try_to_migrate_one()" failed to apply to 6.6-stable tree
@ 2026-09-03 10:49 gregkh
  2026-09-04 10:29 ` [PATCH 6.6.y 1/2] mm: replace pmd_to_swp_entry() with softleaf_from_pmd() Sasha Levin
  0 siblings, 1 reply; 3+ messages in thread
From: gregkh @ 2026-09-03 10:49 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 9be12ffa78cd087d41086f937a156435d4e588e9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090359-effects-precinct-7e44@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 9be12ffa78cd087d41086f937a156435d4e588e9 Mon Sep 17 00:00:00 2001
From: Dev Jain <dev.jain@arm.com>
Date: Fri, 3 Jul 2026 11:41:56 +0000
Subject: [PATCH] mm/rmap: use huge_ptep_get() in try_to_migrate_one()

try_to_migrate_one() is used by folio migration to replace a present
mapping with a migration entry. For hugetlb folios, page_vma_mapped_walk()
returns the pte pointer to the hugetlb folio in pvmw.pte, but the code
reads the huge pte entry 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.

Commit a98a2f0c8ce1 copied the bug from try_to_unmap_one into
try_to_migrate_one.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lore.kernel.org/20260703114202.365553-4-dev.jain@arm.com
Fixes: a98a2f0c8ce1 ("mm/rmap: split migration into its own function")
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/rmap.c b/mm/rmap.c
index e0d7b33ceee4..9939400e77c7 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2500,14 +2500,18 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 		/* Unexpected PMD-mapped THP? */
 		VM_BUG_ON_FOLIO(!pvmw.pte, folio);
 
-		/*
-		 * Handle PFN swap PTEs, such as device-exclusive ones, that
-		 * actually map pages.
-		 */
-		pteval = ptep_get(pvmw.pte);
+		address = pvmw.address;
+		if (folio_test_hugetlb(folio))
+			pteval = huge_ptep_get(mm, address, pvmw.pte);
+		else
+			pteval = ptep_get(pvmw.pte);
 		if (likely(pte_present(pteval))) {
 			pfn = pte_pfn(pteval);
 		} else {
+			/*
+			 * Handle PFN swap PTEs, such as device-exclusive ones,
+			 * that actually map pages.
+			 */
 			const softleaf_t entry = softleaf_from_pte(pteval);
 
 			pfn = softleaf_to_pfn(entry);
@@ -2515,7 +2519,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
 		}
 
 		subpage = folio_page(folio, pfn - folio_pfn(folio));
-		address = pvmw.address;
 		anon_exclusive = folio_test_anon(folio) &&
 				 PageAnonExclusive(subpage);
 


^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-04 10:30 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-09-03 10:49 FAILED: patch "[PATCH] mm/rmap: use huge_ptep_get() in try_to_migrate_one()" failed to apply to 6.6-stable tree gregkh
2026-09-04 10:29 ` [PATCH 6.6.y 1/2] mm: replace pmd_to_swp_entry() with softleaf_from_pmd() Sasha Levin
2026-09-04 10:29   ` [PATCH 6.6.y 2/2] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Sasha Levin

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