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authorMike Rapoport <rppt@linux.vnet.ibm.com>2017-09-07 02:23:02 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-07 03:27:28 +0300
commit8d10396342063c79e92c4e46215370ab7b988569 (patch)
treec0cae3f4c634b760704f3fd8469f04213dc58fe4 /mm/shmem.c
parent0f0796945614b7523987f7eea32407421af4b1ee (diff)
downloadlinux-8d10396342063c79e92c4e46215370ab7b988569.tar.xz
userfaultfd: shmem: add shmem_mfill_zeropage_pte for userfaultfd support
shmem_mfill_zeropage_pte is the low level routine that implements the userfaultfd UFFDIO_ZEROPAGE command. Since for shmem mappings zero pages are always allocated and accounted, the new method is a slight extension of the existing shmem_mcopy_atomic_pte. Link: http://lkml.kernel.org/r/1497939652-16528-4-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Hugh Dickins <hughd@google.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c62
1 files changed, 45 insertions, 17 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index b7d84c4f2a5c..64bdc91187f7 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2207,12 +2207,13 @@ bool shmem_mapping(struct address_space *mapping)
return mapping->a_ops == &shmem_aops;
}
-int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
- pmd_t *dst_pmd,
- struct vm_area_struct *dst_vma,
- unsigned long dst_addr,
- unsigned long src_addr,
- struct page **pagep)
+static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
+ pmd_t *dst_pmd,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr,
+ unsigned long src_addr,
+ bool zeropage,
+ struct page **pagep)
{
struct inode *inode = file_inode(dst_vma->vm_file);
struct shmem_inode_info *info = SHMEM_I(inode);
@@ -2235,17 +2236,22 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
if (!page)
goto out_unacct_blocks;
- page_kaddr = kmap_atomic(page);
- ret = copy_from_user(page_kaddr, (const void __user *)src_addr,
- PAGE_SIZE);
- kunmap_atomic(page_kaddr);
-
- /* fallback to copy_from_user outside mmap_sem */
- if (unlikely(ret)) {
- *pagep = page;
- shmem_inode_unacct_blocks(inode, 1);
- /* don't free the page */
- return -EFAULT;
+ if (!zeropage) { /* mcopy_atomic */
+ page_kaddr = kmap_atomic(page);
+ ret = copy_from_user(page_kaddr,
+ (const void __user *)src_addr,
+ PAGE_SIZE);
+ kunmap_atomic(page_kaddr);
+
+ /* fallback to copy_from_user outside mmap_sem */
+ if (unlikely(ret)) {
+ *pagep = page;
+ shmem_inode_unacct_blocks(inode, 1);
+ /* don't free the page */
+ return -EFAULT;
+ }
+ } else { /* mfill_zeropage_atomic */
+ clear_highpage(page);
}
} else {
page = *pagep;
@@ -2311,6 +2317,28 @@ out_unacct_blocks:
goto out;
}
+int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
+ pmd_t *dst_pmd,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr,
+ unsigned long src_addr,
+ struct page **pagep)
+{
+ return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
+ dst_addr, src_addr, false, pagep);
+}
+
+int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
+ pmd_t *dst_pmd,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr)
+{
+ struct page *page = NULL;
+
+ return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
+ dst_addr, 0, true, &page);
+}
+
#ifdef CONFIG_TMPFS
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_short_symlink_operations;