The patch titled
Subject: userfaultfd: shmem: add shmem_mfill_zeropage_pte for userfaultfd support
has been added to the -mm tree. Its filename is
userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxxxxx
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/shmem_fs.h | 6 +++
mm/shmem.c | 62 ++++++++++++++++++++++++++-----------
2 files changed, 51 insertions(+), 17 deletions(-)
diff -puN include/linux/shmem_fs.h~userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support include/linux/shmem_fs.h
--- a/include/linux/shmem_fs.h~userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support
+++ a/include/linux/shmem_fs.h
@@ -137,9 +137,15 @@ extern int shmem_mcopy_atomic_pte(struct
unsigned long dst_addr,
unsigned long src_addr,
struct page **pagep);
+extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
+ pmd_t *dst_pmd,
+ struct vm_area_struct *dst_vma,
+ unsigned long dst_addr);
#else
#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
src_addr, pagep) ({ BUG(); 0; })
+#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \
+ dst_addr) ({ BUG(); 0; })
#endif
#endif
diff -puN mm/shmem.c~userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support mm/shmem.c
--- a/mm/shmem.c~userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support
+++ a/mm/shmem.c
@@ -2199,12 +2199,13 @@ bool shmem_mapping(struct address_space
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);
@@ -2227,17 +2228,22 @@ int shmem_mcopy_atomic_pte(struct mm_str
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;
@@ -2303,6 +2309,28 @@ 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;
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxxxxxxx are
userfaultfd-non-cooperative-notify-about-unmap-of-destination-during-mremap.patch
userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
shmem-shmem_charge-verify-max_block-is-not-exceeded-before-inode-update.patch
shmem-introduce-shmem_inode_acct_block.patch
userfaultfd-shmem-add-shmem_mfill_zeropage_pte-for-userfaultfd-support.patch
userfaultfd-mcopy_atomic-introduce-mfill_atomic_pte-helper.patch
userfaultfd-shmem-wire-up-shmem_mfill_zeropage_pte.patch
userfaultfd-report-uffdio_zeropage-as-available-for-shmem-vmas.patch
userfaultfd-selftest-enable-testing-of-uffdio_zeropage-for-shmem.patch
--
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