The quilt patch titled
Subject: mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for private mappings
has been removed from the -mm tree. Its filename was
mm-dont-call-vm_ops-huge_fault-in-wp_huge_pmd-wp_huge_pud-for-private-mappings.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: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for private mappings
Date: Wed, 16 Nov 2022 11:26:46 +0100
If we already have a PMD/PUD mapped write-protected in a private mapping
and we want to break COW either due to FAULT_FLAG_WRITE or
FAULT_FLAG_UNSHARE, there is no need to inform the file system just like on
the PTE path.
Let's just split (->zap) + fallback in that case.
This is a preparation for more generic FAULT_FLAG_UNSHARE support in
COW mappings.
Link: https://lkml.kernel.org/r/20221116102659.70287-8-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
--- a/mm/memory.c~mm-dont-call-vm_ops-huge_fault-in-wp_huge_pmd-wp_huge_pud-for-private-mappings
+++ a/mm/memory.c
@@ -4802,6 +4802,7 @@ static inline vm_fault_t create_huge_pmd
static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
{
const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
+ vm_fault_t ret;
if (vma_is_anonymous(vmf->vma)) {
if (likely(!unshare) &&
@@ -4809,11 +4810,13 @@ static inline vm_fault_t wp_huge_pmd(str
return handle_userfault(vmf, VM_UFFD_WP);
return do_huge_pmd_wp_page(vmf);
}
- if (vmf->vma->vm_ops->huge_fault) {
- vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
- if (!(ret & VM_FAULT_FALLBACK))
- return ret;
+ if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
+ if (vmf->vma->vm_ops->huge_fault) {
+ ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ }
}
/* COW or write-notify handled on pte level: split pmd. */
@@ -4839,14 +4842,17 @@ static vm_fault_t wp_huge_pud(struct vm_
{
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
+ vm_fault_t ret;
+
/* 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);
-
- if (!(ret & VM_FAULT_FALLBACK))
- return ret;
+ if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
+ if (vmf->vma->vm_ops->huge_fault) {
+ ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
+ if (!(ret & VM_FAULT_FALLBACK))
+ return ret;
+ }
}
split:
/* COW or write-notify not handled on PUD level: split pud.*/
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
selftests-vm-add-ksm-unmerge-tests.patch
mm-pagewalk-dont-trigger-test_walk-in-walk_page_vma.patch
selftests-vm-add-test-to-measure-madv_unmergeable-performance.patch
mm-ksm-simplify-break_ksm-to-not-rely-on-vm_fault_write.patch
mm-remove-vm_fault_write.patch
mm-ksm-fix-ksm-cow-breaking-with-userfaultfd-wp-via-fault_flag_unshare.patch
mm-pagewalk-add-walk_page_range_vma.patch
mm-ksm-convert-break_ksm-to-use-walk_page_range_vma.patch
mm-gup-remove-foll_migration.patch
