The patch titled
Subject: mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for private mappings
has been added to the -mm mm-unstable branch. Its filename is
mm-dont-call-vm_ops-huge_fault-in-wp_huge_pmd-wp_huge_pud-for-private-mappings.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-dont-call-vm_ops-huge_fault-in-wp_huge_pmd-wp_huge_pud-for-private-mappings.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
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>
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
mm-mprotect-minor-can_change_pte_writable-cleanups.patch
mm-huge_memory-try-avoiding-write-faults-when-changing-pmd-protection.patch
mm-mprotect-factor-out-check-whether-manual-pte-write-upgrades-are-required.patch
mm-autonuma-use-can_change_ptepmd_writable-to-replace-savedwrite.patch
mm-remove-unused-savedwrite-infrastructure.patch
selftests-vm-anon_cow-add-mprotect-optimization-tests.patch
selftests-vm-anon_cow-prepare-for-non-anonymous-cow-tests.patch
selftests-vm-cow-basic-cow-tests-for-non-anonymous-pages.patch
selftests-vm-cow-r-o-long-term-pinning-reliability-tests-for-non-anon-pages.patch
mm-add-early-fault_flag_unshare-consistency-checks.patch
mm-add-early-fault_flag_write-consistency-checks.patch
mm-rework-handling-in-do_wp_page-based-on-private-vs-shared-mappings.patch
mm-dont-call-vm_ops-huge_fault-in-wp_huge_pmd-wp_huge_pud-for-private-mappings.patch
mm-extend-fault_flag_unshare-support-to-anything-in-a-cow-mapping.patch
mm-gup-reliable-r-o-long-term-pinning-in-cow-mappings.patch
rdma-umem-remove-foll_force-usage.patch
rdma-usnic-remove-foll_force-usage.patch
rdma-siw-remove-foll_force-usage.patch
media-videobuf-dma-sg-remove-foll_force-usage.patch
drm-etnaviv-remove-foll_force-usage.patch
media-pci-ivtv-remove-foll_force-usage.patch
mm-frame-vector-remove-foll_force-usage.patch
drm-exynos-remove-foll_force-usage.patch
rdma-hw-qib-qib_user_pages-remove-foll_force-usage.patch
habanalabs-remove-foll_force-usage.patch
