+ selftests-udmabuf-add-a-test-to-pin-first-before-writing-to-memfd.patch added to mm-new branch

+ selftests-udmabuf-add-a-test-to-pin-first-before-writing-to-memfd.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: selftests/udmabuf: add a test to pin first before writing to memfd
has been added to the -mm mm-new branch.  Its filename is
     selftests-udmabuf-add-a-test-to-pin-first-before-writing-to-memfd.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-udmabuf-add-a-test-to-pin-first-before-writing-to-memfd.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Vivek Kasireddy <vivek.kasireddy@intel.com>
Subject: selftests/udmabuf: add a test to pin first before writing to memfd
Date: Tue, 17 Jun 2025 22:30:55 -0700

Unlike the existing tests, this new test will create a memfd (backed by
hugetlb) and pin the folios in it (a small subset) before writing/
populating it with data.  This is a valid use-case that invokes the
memfd_alloc_folio() kernel API and is expected to work unless there aren't
enough hugetlb folios to satisfy the allocation needs.

Link: https://lkml.kernel.org/r/20250618053415.1036185-4-vivek.kasireddy@intel.com
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Steve Sistare <steven.sistare@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/drivers/dma-buf/udmabuf.c |   20 +++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/drivers/dma-buf/udmabuf.c~selftests-udmabuf-add-a-test-to-pin-first-before-writing-to-memfd
+++ a/tools/testing/selftests/drivers/dma-buf/udmabuf.c
@@ -138,7 +138,7 @@ int main(int argc, char *argv[])
 	void *addr1, *addr2;
 
 	ksft_print_header();
-	ksft_set_plan(6);
+	ksft_set_plan(7);
 
 	devfd = open("/dev/udmabuf", O_RDWR);
 	if (devfd < 0) {
@@ -250,6 +250,24 @@ int main(int argc, char *argv[])
 
 	close(buf);
 	close(memfd);
+
+	/* same test as above but we pin first before writing to memfd */
+	page_size = getpagesize() * 512; /* 2 MB */
+	size = MEMFD_SIZE * page_size;
+	memfd = create_memfd_with_seals(size, true);
+	buf = create_udmabuf_list(devfd, memfd, size);
+	addr2 = mmap_fd(buf, NUM_PAGES * NUM_ENTRIES * getpagesize());
+	addr1 = mmap_fd(memfd, size);
+	write_to_memfd(addr1, size, 'a');
+	write_to_memfd(addr1, size, 'b');
+	ret = compare_chunks(addr1, addr2, size);
+	if (ret < 0)
+		ksft_test_result_fail("%s: [FAIL,test-7]\n", TEST_PREFIX);
+	else
+		ksft_test_result_pass("%s: [PASS,test-7]\n", TEST_PREFIX);
+
+	close(buf);
+	close(memfd);
 	close(devfd);
 
 	ksft_print_msg("%s: ok\n", TEST_PREFIX);
_

Patches currently in -mm which might be from vivek.kasireddy@intel.com are

mm-hugetlb-make-hugetlb_reserve_pages-return-nr-of-entries-updated.patch
mm-memfd-reserve-hugetlb-folios-before-allocation.patch
selftests-udmabuf-add-a-test-to-pin-first-before-writing-to-memfd.patch