From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
The shmem_mcopy_atomic_pte implements low lever part of UFFDIO_COPY
operation for shared memory VMAs. It's based on mcopy_atomic_pte with
adjustments necessary for shared memory pages.
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
mm/userfaultfd.c | 34 +++++++++++++++++++++-------------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 31207b4..a0817cc 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -16,6 +16,7 @@
#include <linux/mmu_notifier.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
+#include <linux/shmem_fs.h>
#include <asm/tlbflush.h>
#include "internal.h"
@@ -369,7 +370,9 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
*/
err = -EINVAL;
dst_vma = find_vma(dst_mm, dst_start);
- if (!dst_vma || (dst_vma->vm_flags & VM_SHARED))
+ if (!dst_vma)
+ goto out_unlock;
+ if (!vma_is_shmem(dst_vma) && dst_vma->vm_flags & VM_SHARED)
goto out_unlock;
if (dst_start < dst_vma->vm_start ||
dst_start + len > dst_vma->vm_end)
@@ -394,11 +397,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
if (!dst_vma->vm_userfaultfd_ctx.ctx)
goto out_unlock;
- /*
- * FIXME: only allow copying on anonymous vmas, tmpfs should
- * be added.
- */
- if (!vma_is_anonymous(dst_vma))
+ if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
goto out_unlock;
/*
@@ -407,7 +406,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
* dst_vma.
*/
err = -ENOMEM;
- if (unlikely(anon_vma_prepare(dst_vma)))
+ if (vma_is_anonymous(dst_vma) && unlikely(anon_vma_prepare(dst_vma)))
goto out_unlock;
while (src_addr < src_start + len) {
@@ -444,12 +443,21 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
BUG_ON(pmd_none(*dst_pmd));
BUG_ON(pmd_trans_huge(*dst_pmd));
- if (!zeropage)
- err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
- dst_addr, src_addr, &page);
- else
- err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma,
- dst_addr);
+ if (vma_is_anonymous(dst_vma)) {
+ if (!zeropage)
+ err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
+ dst_addr, src_addr,
+ &page);
+ else
+ err = mfill_zeropage_pte(dst_mm, dst_pmd,
+ dst_vma, dst_addr);
+ } else {
+ err = -EINVAL; /* if zeropage is true return -EINVAL */
+ if (likely(!zeropage))
+ err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd,
+ dst_vma, dst_addr,
+ src_addr, &page);
+ }
cond_resched();
--
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