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Date: Fri, 15 Jan 2021 12:08:56 -0500
From: Peter Xu <peterx@...hat.com>
To: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc: Mike Rapoport <rppt@...ux.vnet.ibm.com>,
Mike Kravetz <mike.kravetz@...cle.com>, peterx@...hat.com,
Jerome Glisse <jglisse@...hat.com>,
"Kirill A . Shutemov" <kirill@...temov.name>,
Hugh Dickins <hughd@...gle.com>,
Axel Rasmussen <axelrasmussen@...gle.com>,
Matthew Wilcox <willy@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Nadav Amit <nadav.amit@...il.com>
Subject: [PATCH RFC 19/30] hugetlb/userfaultfd: Take care of UFFDIO_COPY_MODE_WP
Firstly, pass the wp_copy variable into hugetlb_mcopy_atomic_pte() thoughout
the stack. Then, apply the UFFD_WP bit if UFFDIO_COPY_MODE_WP is with
UFFDIO_COPY. Introduce huge_pte_mkuffd_wp() for it.
Note that similar to how we've handled shmem, we'd better keep setting the
dirty bit even if UFFDIO_COPY_MODE_WP is provided, so that the core mm will
know this page contains valid data and never drop it.
Signed-off-by: Peter Xu <peterx@...hat.com>
---
include/asm-generic/hugetlb.h | 5 +++++
include/linux/hugetlb.h | 6 ++++--
mm/hugetlb.c | 9 +++++++--
mm/userfaultfd.c | 12 ++++++++----
4 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/include/asm-generic/hugetlb.h b/include/asm-generic/hugetlb.h
index 8e1e6244a89d..548212eccbd6 100644
--- a/include/asm-generic/hugetlb.h
+++ b/include/asm-generic/hugetlb.h
@@ -27,6 +27,11 @@ static inline pte_t huge_pte_mkdirty(pte_t pte)
return pte_mkdirty(pte);
}
+static inline pte_t huge_pte_mkuffd_wp(pte_t pte)
+{
+ return pte_mkuffd_wp(pte);
+}
+
static inline pte_t huge_pte_modify(pte_t pte, pgprot_t newprot)
{
return pte_modify(pte, newprot);
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ebca2ef02212..bd061f7eedcb 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -138,7 +138,8 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
- struct page **pagep);
+ struct page **pagep,
+ bool wp_copy);
int hugetlb_reserve_pages(struct inode *inode, long from, long to,
struct vm_area_struct *vma,
vm_flags_t vm_flags);
@@ -313,7 +314,8 @@ static inline int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
- struct page **pagep)
+ struct page **pagep,
+ bool wp_copy)
{
BUG();
return 0;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index dcbbba53bd10..563b8f70537f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4624,7 +4624,8 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
- struct page **pagep)
+ struct page **pagep,
+ bool wp_copy)
{
struct address_space *mapping;
pgoff_t idx;
@@ -4717,8 +4718,12 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
}
_dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE);
- if (dst_vma->vm_flags & VM_WRITE)
+ if (dst_vma->vm_flags & VM_WRITE) {
_dst_pte = huge_pte_mkdirty(_dst_pte);
+ if (wp_copy)
+ _dst_pte = huge_pte_mkuffd_wp(
+ huge_pte_wrprotect(_dst_pte));
+ }
_dst_pte = pte_mkyoung(_dst_pte);
set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 6d4b3b7c7f9f..b00e5e6b8b8b 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -207,7 +207,8 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
- bool zeropage)
+ bool zeropage,
+ bool wp_copy)
{
int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED;
int vm_shared = dst_vma->vm_flags & VM_SHARED;
@@ -306,7 +307,8 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
}
err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
- dst_addr, src_addr, &page);
+ dst_addr, src_addr, &page,
+ wp_copy);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
i_mmap_unlock_read(mapping);
@@ -408,7 +410,8 @@ extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
- bool zeropage);
+ bool zeropage,
+ bool wp_copy);
#endif /* CONFIG_HUGETLB_PAGE */
static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
@@ -527,7 +530,8 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
*/
if (is_vm_hugetlb_page(dst_vma))
return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
- src_start, len, zeropage);
+ src_start, len, zeropage,
+ wp_copy);
if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
goto out_unlock;
--
2.26.2
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