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mm-thp-carry-over-dirty-bit-when-thp-splits-on-pmd.patch removed from -mm tree

merged mm-stable Andrew Morton 1 participant 1 message Sep 27, 2022

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The quilt patch titled
Subject: mm/thp: carry over dirty bit when thp splits on pmd
has been removed from the -mm tree. Its filename was
mm-thp-carry-over-dirty-bit-when-thp-splits-on-pmd.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Peter Xu <[email protected]>
Subject: mm/thp: carry over dirty bit when thp splits on pmd
Date: Thu, 11 Aug 2022 12:13:28 -0400

Carry over the dirty bit from pmd to pte when a huge pmd splits. It shouldn't be a correctness issue since when pmd_dirty() we'll have the page marked dirty anyway, however having dirty bit carried over helps the next initial writes of split ptes on some archs like x86.

Link https://lkml.kernel.org/r/[email protected] open here
Signed-off-by Peter Xu <[email protected]>
Reviewed-by Huang Ying <[email protected]>
Cc Alistair Popple <[email protected]>
Cc Andi Kleen <[email protected]>
Cc Andrea Arcangeli <[email protected]>
Cc David Hildenbrand <[email protected]>
Cc Hugh Dickins <[email protected]>
Cc "Kirill A . Shutemov" <[email protected]>
Cc Minchan Kim <[email protected]>
Cc Nadav Amit <[email protected]>
Cc Vlastimil Babka <[email protected]>
Cc Dave Hansen <[email protected]>
Signed-off-by Andrew Morton <[email protected]>

---

 mm/huge_memory.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
mm/huge_memory.c renamed from mm/huge_memory.c~mm-thp-carry-over-dirty-bit-when-thp-splits-on-pmd +7 -2
@@ -2037,7 +2037,7 @@ static void __split_huge_pmd_locked(stru
 	pgtable_t pgtable;
 	pmd_t old_pmd, _pmd;
 	bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
-	bool anon_exclusive = false;
+	bool anon_exclusive = false, dirty = false;
 	unsigned long addr;
 	int i;
 

@@ -2126,8 +2126,10 @@ static void __split_huge_pmd_locked(stru
 		uffd_wp = pmd_swp_uffd_wp(old_pmd);
 	} else {
 		page = pmd_page(old_pmd);
-		if (pmd_dirty(old_pmd))
+		if (pmd_dirty(old_pmd)) {
+			dirty = true;
 			SetPageDirty(page);
+		}
 		write = pmd_write(old_pmd);
 		young = pmd_young(old_pmd);
 		soft_dirty = pmd_soft_dirty(old_pmd);

@@ -2195,6 +2197,9 @@ static void __split_huge_pmd_locked(stru
 				entry = pte_wrprotect(entry);
 			if (!young)
 				entry = pte_mkold(entry);
+			/* NOTE: this may set soft-dirty too on some archs */
+			if (dirty)
+				entry = pte_mkdirty(entry);
 			if (soft_dirty)
 				entry = pte_mksoft_dirty(entry);
 			if (uffd_wp)

_

Patches currently in -mm which might be from [email protected] are