FAILED: patch "[PATCH] mm: migrate_device: fix pte_pfn/pte_dirty called on" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] mm: migrate_device: fix pte_pfn/pte_dirty called on" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 63867c82d0c0c2d182016a32b1cc0103116b0ea5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026080539-snowsuit-kept-385b@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 63867c82d0c0c2d182016a32b1cc0103116b0ea5 Mon Sep 17 00:00:00 2001
From: Kefeng Wang <wangkefeng.wang@huawei.com>
Date: Mon, 6 Jul 2026 19:19:58 +0800
Subject: [PATCH] mm: migrate_device: fix pte_pfn/pte_dirty called on
 non-present PTE

pte_pfn() and pte_dirty() have undefined behaviour when called on a
non-present PTE. In migrate_vma_collect_pmd(), these functions may be
invoked on non-present entries (e.g., device-private entries), leading
to potential crashes from pte_pfn() or incorrect dirty folio accounting
from pte_dirty(). Fix both by guarding with pte_present() checks.

Link: https://lore.kernel.org/20260708003955.4024340-1-wangkefeng.wang@huawei.com
Link: https://lore.kernel.org/20260706111958.3649651-1-wangkefeng.wang@huawei.com
Fixes: fd35ca3d12cc ("mm/migrate_device.c: copy pte dirty bit to page")
Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 554754eb26ff..908d2d4ec43a 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -401,7 +401,8 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 			bool anon_exclusive;
 			pte_t swp_pte;
 
-			flush_cache_page(vma, addr, pte_pfn(pte));
+			if (pte_present(pte))
+				flush_cache_page(vma, addr, pte_pfn(pte));
 			anon_exclusive = folio_test_anon(folio) &&
 					  PageAnonExclusive(page);
 			if (anon_exclusive) {
@@ -422,7 +423,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 			migrate->cpages++;
 
 			/* Set the dirty flag on the folio now the pte is gone. */
-			if (pte_dirty(pte))
+			if (pte_present(pte) && pte_dirty(pte))
 				folio_mark_dirty(folio);
 
 			/* Setup special migration page table entry */

[PATCH 6.1.y 1/2] mm/migrate_device: page_remove_rmap() -> folio_remove_rmap_pte()

[Sasha Levin]

From: David Hildenbrand <david@redhat.com>

[ Upstream commit 5b205c7f2684764c8a9cc3442986623d4d6e87f1 ]

Let's convert migrate_vma_collect_pmd().  While at it, perform more folio
conversion.

Link: https://lkml.kernel.org/r/20231220224504.646757-30-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 63867c82d0c0 ("mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/migrate_device.c | 39 +++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 18 deletions(-)

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index afe3b2d2e7b9d..e198569bb3324 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -114,6 +114,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 
 	for (; addr < end; addr += PAGE_SIZE, ptep++) {
 		unsigned long mpfn = 0, pfn;
+		struct folio *folio;
 		struct page *page;
 		swp_entry_t entry;
 		pte_t pte;
@@ -175,41 +176,43 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 		}
 
 		/*
-		 * By getting a reference on the page we pin it and that blocks
+		 * By getting a reference on the folio we pin it and that blocks
 		 * any kind of migration. Side effect is that it "freezes" the
 		 * pte.
 		 *
-		 * We drop this reference after isolating the page from the lru
-		 * for non device page (device page are not on the lru and thus
+		 * We drop this reference after isolating the folio from the lru
+		 * for non device folio (device folio are not on the lru and thus
 		 * can't be dropped from it).
 		 */
-		get_page(page);
+		folio = page_folio(page);
+		folio_get(folio);
 
 		/*
-		 * We rely on trylock_page() to avoid deadlock between
+		 * We rely on folio_trylock() to avoid deadlock between
 		 * concurrent migrations where each is waiting on the others
-		 * page lock. If we can't immediately lock the page we fail this
+		 * folio lock. If we can't immediately lock the folio we fail this
 		 * migration as it is only best effort anyway.
 		 *
-		 * If we can lock the page it's safe to set up a migration entry
-		 * now. In the common case where the page is mapped once in a
+		 * If we can lock the folio it's safe to set up a migration entry
+		 * now. In the common case where the folio is mapped once in a
 		 * single process setting up the migration entry now is an
 		 * optimisation to avoid walking the rmap later with
 		 * try_to_migrate().
 		 */
-		if (trylock_page(page)) {
+		if (folio_trylock(folio)) {
 			bool anon_exclusive;
 			pte_t swp_pte;
 
-			flush_cache_page(vma, addr, pte_pfn(*ptep));
-			anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
+			flush_cache_page(vma, addr, pte_pfn(pte));
+			anon_exclusive = folio_test_anon(folio) &&
+					  PageAnonExclusive(page);
 			if (anon_exclusive) {
 				pte = ptep_clear_flush(vma, addr, ptep);
 
 				if (page_try_share_anon_rmap(page)) {
 					set_pte_at(mm, addr, ptep, pte);
-					unlock_page(page);
-					put_page(page);
+					folio_unlock(folio);
+					folio_put(folio);
 					mpfn = 0;
 					goto next;
 				}
@@ -221,7 +224,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 
 			/* Set the dirty flag on the folio now the pte is gone. */
 			if (pte_dirty(pte))
-				folio_mark_dirty(page_folio(page));
+				folio_mark_dirty(folio);
 
 			/* Setup special migration page table entry */
 			if (mpfn & MIGRATE_PFN_WRITE)
@@ -255,16 +258,16 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 
 			/*
 			 * This is like regular unmap: we remove the rmap and
-			 * drop page refcount. Page won't be freed, as we took
-			 * a reference just above.
+			 * drop the folio refcount. The folio won't be freed, as
+			 * we took a reference just above.
 			 */
 			page_remove_rmap(page, vma, false);
-			put_page(page);
+			folio_put(folio);
 
 			if (pte_present(pte))
 				unmapped++;
 		} else {
-			put_page(page);
+			folio_put(folio);
 			mpfn = 0;
 		}
 
-- 
2.53.0

[PATCH 6.1.y 2/2] mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE

[Sasha Levin]

From: Kefeng Wang <wangkefeng.wang@huawei.com>

[ Upstream commit 63867c82d0c0c2d182016a32b1cc0103116b0ea5 ]

pte_pfn() and pte_dirty() have undefined behaviour when called on a
non-present PTE. In migrate_vma_collect_pmd(), these functions may be
invoked on non-present entries (e.g., device-private entries), leading
to potential crashes from pte_pfn() or incorrect dirty folio accounting
from pte_dirty(). Fix both by guarding with pte_present() checks.

Link: https://lore.kernel.org/20260708003955.4024340-1-wangkefeng.wang@huawei.com
Link: https://lore.kernel.org/20260706111958.3649651-1-wangkefeng.wang@huawei.com
Fixes: fd35ca3d12cc ("mm/migrate_device.c: copy pte dirty bit to page")
Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ying Huang <ying.huang@linux.alibaba.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/migrate_device.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index e198569bb3324..cd7248a2c8c23 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -203,7 +203,8 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 			bool anon_exclusive;
 			pte_t swp_pte;
 
-			flush_cache_page(vma, addr, pte_pfn(pte));
+			if (pte_present(pte))
+				flush_cache_page(vma, addr, pte_pfn(pte));
 			anon_exclusive = folio_test_anon(folio) &&
 					  PageAnonExclusive(page);
 			if (anon_exclusive) {
@@ -223,7 +224,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 			migrate->cpages++;
 
 			/* Set the dirty flag on the folio now the pte is gone. */
-			if (pte_dirty(pte))
+			if (pte_present(pte) && pte_dirty(pte))
 				folio_mark_dirty(folio);
 
 			/* Setup special migration page table entry */
-- 
2.53.0