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Message-Id: <20220405014906.14708-1-peterx@redhat.com>
Date: Mon, 4 Apr 2022 21:49:06 -0400
From: Peter Xu <peterx@...hat.com>
To: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc: Mike Kravetz <mike.kravetz@...cle.com>,
Nadav Amit <nadav.amit@...il.com>,
Matthew Wilcox <willy@...radead.org>,
Mike Rapoport <rppt@...ux.vnet.ibm.com>,
David Hildenbrand <david@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Jerome Glisse <jglisse@...hat.com>,
"Kirill A . Shutemov" <kirill@...temov.name>,
Andrea Arcangeli <aarcange@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Axel Rasmussen <axelrasmussen@...gle.com>,
Alistair Popple <apopple@...dia.com>, peterx@...hat.com
Subject: [PATCH v8 14/23] mm/hugetlb: Handle UFFDIO_WRITEPROTECT
This starts from passing cp_flags into hugetlb_change_protection() so hugetlb
will be able to handle MM_CP_UFFD_WP[_RESOLVE] requests.
huge_pte_clear_uffd_wp() is introduced to handle the case where the
UFFDIO_WRITEPROTECT is requested upon migrating huge page entries.
Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
Signed-off-by: Peter Xu <peterx@...hat.com>
---
include/linux/hugetlb.h | 6 ++++--
mm/hugetlb.c | 13 ++++++++++++-
mm/mprotect.c | 3 ++-
mm/userfaultfd.c | 8 ++++++++
4 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 6347298778b6..38c5ac28b787 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -210,7 +210,8 @@ struct page *follow_huge_pgd(struct mm_struct *mm, unsigned long address,
int pmd_huge(pmd_t pmd);
int pud_huge(pud_t pud);
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
- unsigned long address, unsigned long end, pgprot_t newprot);
+ unsigned long address, unsigned long end, pgprot_t newprot,
+ unsigned long cp_flags);
bool is_hugetlb_entry_migration(pte_t pte);
void hugetlb_unshare_all_pmds(struct vm_area_struct *vma);
@@ -391,7 +392,8 @@ static inline void move_hugetlb_state(struct page *oldpage,
static inline unsigned long hugetlb_change_protection(
struct vm_area_struct *vma, unsigned long address,
- unsigned long end, pgprot_t newprot)
+ unsigned long end, pgprot_t newprot,
+ unsigned long cp_flags)
{
return 0;
}
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c94deead22b2..2401dd5997b7 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6207,7 +6207,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
}
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
- unsigned long address, unsigned long end, pgprot_t newprot)
+ unsigned long address, unsigned long end,
+ pgprot_t newprot, unsigned long cp_flags)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long start = address;
@@ -6217,6 +6218,8 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long pages = 0;
bool shared_pmd = false;
struct mmu_notifier_range range;
+ bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
+ bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
/*
* In the case of shared PMDs, the area to flush could be beyond
@@ -6263,6 +6266,10 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
entry = make_readable_migration_entry(
swp_offset(entry));
newpte = swp_entry_to_pte(entry);
+ if (uffd_wp)
+ newpte = pte_swp_mkuffd_wp(newpte);
+ else if (uffd_wp_resolve)
+ newpte = pte_swp_clear_uffd_wp(newpte);
set_huge_swap_pte_at(mm, address, ptep,
newpte, huge_page_size(h));
pages++;
@@ -6277,6 +6284,10 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
old_pte = huge_ptep_modify_prot_start(vma, address, ptep);
pte = huge_pte_modify(old_pte, newprot);
pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
+ if (uffd_wp)
+ pte = huge_pte_mkuffd_wp(huge_pte_wrprotect(pte));
+ else if (uffd_wp_resolve)
+ pte = huge_pte_clear_uffd_wp(pte);
huge_ptep_modify_prot_commit(vma, address, ptep, old_pte, pte);
pages++;
}
diff --git a/mm/mprotect.c b/mm/mprotect.c
index e0a567b66d07..6b0e8c213508 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -455,7 +455,8 @@ unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
if (is_vm_hugetlb_page(vma))
- pages = hugetlb_change_protection(vma, start, end, newprot);
+ pages = hugetlb_change_protection(vma, start, end, newprot,
+ cp_flags);
else
pages = change_protection_range(vma, start, end, newprot,
cp_flags);
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index da0b3ed2a6b5..58d67f2bf980 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -704,6 +704,7 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
atomic_t *mmap_changing)
{
struct vm_area_struct *dst_vma;
+ unsigned long page_mask;
pgprot_t newprot;
int err;
@@ -740,6 +741,13 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
if (!vma_is_anonymous(dst_vma))
goto out_unlock;
+ if (is_vm_hugetlb_page(dst_vma)) {
+ err = -EINVAL;
+ page_mask = vma_kernel_pagesize(dst_vma) - 1;
+ if ((start & page_mask) || (len & page_mask))
+ goto out_unlock;
+ }
+
if (enable_wp)
newprot = vm_get_page_prot(dst_vma->vm_flags & ~(VM_WRITE));
else
--
2.32.0
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