[merged mm-hotfixes-stable] mm-split-huge-pud-on-wp_huge_pud-fallback.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

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The quilt patch titled
     Subject: mm: split huge PUD on wp_huge_pud fallback
has been removed from the -mm tree.  Its filename was
     mm-split-huge-pud-on-wp_huge_pud-fallback.patch

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

------------------------------------------------------
From: "Gowans, James" <jgowans@amazon.com>
Subject: mm: split huge PUD on wp_huge_pud fallback
Date: Thu, 23 Jun 2022 05:24:03 +0000

Currently the implementation will split the PUD when a fallback is taken
inside the create_huge_pud function.  This isn't where it should be done:
the splitting should be done in wp_huge_pud, just like it's done for PMDs.
Reason being that if a callback is taken during create, there is no PUD
yet so nothing to split, whereas if a fallback is taken when encountering
a write protection fault there is something to split.

It looks like this was the original intention with the commit where the
splitting was introduced, but somehow it got moved to the wrong place
between v1 and v2 of the patch series.  Rebase mistake perhaps.

Link: https://lkml.kernel.org/r/6f48d622eb8bce1ae5dd75327b0b73894a2ec407.camel@amazon.com
Fixes: 327e9fd48972 ("mm: Split huge pages on write-notify or COW")
Signed-off-by: James Gowans <jgowans@amazon.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |   27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

--- a/mm/memory.c~mm-split-huge-pud-on-wp_huge_pud-fallback
+++ a/mm/memory.c
@@ -4802,6 +4802,19 @@ static vm_fault_t create_huge_pud(struct
 	defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
 	/* No support for anonymous transparent PUD pages yet */
 	if (vma_is_anonymous(vmf->vma))
+		return VM_FAULT_FALLBACK;
+	if (vmf->vma->vm_ops->huge_fault)
+		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+	return VM_FAULT_FALLBACK;
+}
+
+static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
+{
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) &&			\
+	defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+	/* No support for anonymous transparent PUD pages yet */
+	if (vma_is_anonymous(vmf->vma))
 		goto split;
 	if (vmf->vma->vm_ops->huge_fault) {
 		vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
@@ -4812,19 +4825,7 @@ static vm_fault_t create_huge_pud(struct
 split:
 	/* COW or write-notify not handled on PUD level: split pud.*/
 	__split_huge_pud(vmf->vma, vmf->pud, vmf->address);
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-	return VM_FAULT_FALLBACK;
-}
-
-static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
-{
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	/* No support for anonymous transparent PUD pages yet */
-	if (vma_is_anonymous(vmf->vma))
-		return VM_FAULT_FALLBACK;
-	if (vmf->vma->vm_ops->huge_fault)
-		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 	return VM_FAULT_FALLBACK;
 }
 
_

Patches currently in -mm which might be from jgowans@amazon.com are