selftests-mm-uffd-dont-treat-uffdio_copy-enoent-as-a-failure.patch removed from -mm tree

The quilt patch titled
Subject: selftests/mm/uffd: don't treat UFFDIO_COPY -ENOENT as a failure
has been removed from the -mm tree. Its filename was
selftests-mm-uffd-dont-treat-uffdio_copy-enoent-as-a-failure.patch

This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: "Mike Rapoport (Microsoft)" <[email protected]>
Subject: selftests/mm/uffd: don't treat UFFDIO_COPY -ENOENT as a failure
Date: Wed, 1 Jul 2026 23:09:32 +0300

Non-cooperarive uffd events are inherently racy and can happen in parallel with other userfaultfd operations.

During event tests in uffd-unit-tests, the uffd monitor calls UFFDIO_UNREGISTER upon receiving UFFD_EVENT_REMOVE.

In parallel, the faulting_process() verifies that the removed memory is actually zeroed.

If a verification read wins the race with UFFDIO_UNREGISTER, it causes a missing fault that uffd monitor would receive after UFFDIO_UNREGISTER is complete. The monitor resolves the fault using UFFDIO_COPY that fails with -ENOENT which means that VMA has been changed (see commit 27d02568f529 ("userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found")).

Treat -ENOENT returned by UFFDIO_COPY as non-fatal, the same way -EEXIST is treated for concurrent faults, and don't fail the test.

---

 tools/testing/selftests/mm/uffd-common.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

@@ -639,8 +639,13 @@ int __copy_page(uffd_global_test_opts_t
 		uffdio_copy.mode = 0;
 	uffdio_copy.copy = 0;
 	if (ioctl(gopts->uffd, UFFDIO_COPY, &uffdio_copy)) {
-		/* real retval in ufdio_copy.copy */
-		if (uffdio_copy.copy != -EEXIST)
+		/*
+		 * real retval in uffdio_copy.copy
+		 *
+		 * -EEXIST: the page was faulted in concurrently
+		 * -ENOENT: the destination range was concurrently removed
+		 */
+		if (uffdio_copy.copy != -EEXIST && uffdio_copy.copy != -ENOENT)
 			err("UFFDIO_COPY error: %"PRId64,
 			    (int64_t)uffdio_copy.copy);
 		wake_range(gopts->uffd, uffdio_copy.dst, gopts->page_size);

_

Patches currently in -mm which might be from [email protected] are

mm-split-out-mm_init-and-memblock-declarations-from-internalh.patch mm-split-out-mm_init-and-memblock-declarations-from-internalh-fix.patch mm-split-out-sparse-declarations-from-internalh.patch mm-split-out-vmalloc-declarations-from-internalh.patch