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Diffstat (limited to 'fs/userfaultfd.c')
-rw-r--r--fs/userfaultfd.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index cec550c8468f..123bf7d516fc 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -62,6 +62,8 @@ struct userfaultfd_ctx {
enum userfaultfd_state state;
/* released */
bool released;
+ /* memory mappings are changing because of non-cooperative event */
+ bool mmap_changing;
/* mm with one ore more vmas attached to this userfaultfd_ctx */
struct mm_struct *mm;
};
@@ -641,6 +643,7 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
* already released.
*/
out:
+ WRITE_ONCE(ctx->mmap_changing, false);
userfaultfd_ctx_put(ctx);
}
@@ -686,10 +689,12 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
ctx->state = UFFD_STATE_RUNNING;
ctx->features = octx->features;
ctx->released = false;
+ ctx->mmap_changing = false;
ctx->mm = vma->vm_mm;
mmgrab(ctx->mm);
userfaultfd_ctx_get(octx);
+ WRITE_ONCE(octx->mmap_changing, true);
fctx->orig = octx;
fctx->new = ctx;
list_add_tail(&fctx->list, fcs);
@@ -732,6 +737,7 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma,
if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
vm_ctx->ctx = ctx;
userfaultfd_ctx_get(ctx);
+ WRITE_ONCE(ctx->mmap_changing, true);
}
}
@@ -772,6 +778,7 @@ bool userfaultfd_remove(struct vm_area_struct *vma,
return true;
userfaultfd_ctx_get(ctx);
+ WRITE_ONCE(ctx->mmap_changing, true);
up_read(&mm->mmap_sem);
msg_init(&ewq.msg);
@@ -815,6 +822,7 @@ int userfaultfd_unmap_prep(struct vm_area_struct *vma,
return -ENOMEM;
userfaultfd_ctx_get(ctx);
+ WRITE_ONCE(ctx->mmap_changing, true);
unmap_ctx->ctx = ctx;
unmap_ctx->start = start;
unmap_ctx->end = end;
@@ -1653,6 +1661,10 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
user_uffdio_copy = (struct uffdio_copy __user *) arg;
+ ret = -EAGAIN;
+ if (READ_ONCE(ctx->mmap_changing))
+ goto out;
+
ret = -EFAULT;
if (copy_from_user(&uffdio_copy, user_uffdio_copy,
/* don't copy "copy" last field */
@@ -1674,7 +1686,7 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
goto out;
if (mmget_not_zero(ctx->mm)) {
ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
- uffdio_copy.len);
+ uffdio_copy.len, &ctx->mmap_changing);
mmput(ctx->mm);
} else {
return -ESRCH;
@@ -1705,6 +1717,10 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg;
+ ret = -EAGAIN;
+ if (READ_ONCE(ctx->mmap_changing))
+ goto out;
+
ret = -EFAULT;
if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage,
/* don't copy "zeropage" last field */
@@ -1721,7 +1737,8 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
if (mmget_not_zero(ctx->mm)) {
ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
- uffdio_zeropage.range.len);
+ uffdio_zeropage.range.len,
+ &ctx->mmap_changing);
mmput(ctx->mm);
} else {
return -ESRCH;
@@ -1900,6 +1917,7 @@ SYSCALL_DEFINE1(userfaultfd, int, flags)
ctx->features = 0;
ctx->state = UFFD_STATE_WAIT_API;
ctx->released = false;
+ ctx->mmap_changing = false;
ctx->mm = current->mm;
/* prevent the mm struct to be freed */
mmgrab(ctx->mm);