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-rw-r--r--mm/userfaultfd.c22
1 files changed, 17 insertions, 5 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 39791b81ede7..5029f241908f 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -404,7 +404,8 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
- bool zeropage)
+ bool zeropage,
+ bool *mmap_changing)
{
struct vm_area_struct *dst_vma;
ssize_t err;
@@ -431,6 +432,15 @@ retry:
down_read(&dst_mm->mmap_sem);
/*
+ * If memory mappings are changing because of non-cooperative
+ * operation (e.g. mremap) running in parallel, bail out and
+ * request the user to retry later
+ */
+ err = -EAGAIN;
+ if (mmap_changing && READ_ONCE(*mmap_changing))
+ goto out_unlock;
+
+ /*
* Make sure the vma is not shared, that the dst range is
* both valid and fully within a single existing vma.
*/
@@ -563,13 +573,15 @@ out:
}
ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
- unsigned long src_start, unsigned long len)
+ unsigned long src_start, unsigned long len,
+ bool *mmap_changing)
{
- return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
+ return __mcopy_atomic(dst_mm, dst_start, src_start, len, false,
+ mmap_changing);
}
ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
- unsigned long len)
+ unsigned long len, bool *mmap_changing)
{
- return __mcopy_atomic(dst_mm, start, 0, len, true);
+ return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing);
}