[to-be-updated] selftest-mm-register-existing-mapping-with-userfaultfd-in-hugepage-mremap.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

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The quilt patch titled
     Subject: selftest/mm: register existing mapping with userfaultfd in hugepage-mremap
has been removed from the -mm tree.  Its filename was
     selftest-mm-register-existing-mapping-with-userfaultfd-in-hugepage-mremap.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: Sayali Patil <sayalip@linux.ibm.com>
Subject: selftest/mm: register existing mapping with userfaultfd in hugepage-mremap
Date: Thu, 12 Mar 2026 17:55:34 +0530

Previously, register_region_with_uffd() created a new anonymous mapping
and overwrote the address supplied by the caller before registering the
range with userfaultfd.

As a result, userfaultfd was applied to an unrelated anonymous mapping
instead of the hugetlb region used by the test.

Remove the extra mmap() and register the caller-provided address range
directly using UFFDIO_REGISTER_MODE_MISSING, so that faults are generated
for the hugetlb mapping used by the test.

This ensures userfaultfd operates on the actual hugetlb test region and
validates the expected fault handling.

Before patch:
 running ./hugepage-mremap
 -------------------------
 TAP version 13
 1..1
  Map haddr: Returned address is 0x7eaa40000000
  Map daddr: Returned address is 0x7daa40000000
  Map vaddr: Returned address is 0x7faa40000000
  Address returned by mmap() = 0x7fff9d000000
  Mremap: Returned address is 0x7faa40000000
  First hex is 0
  First hex is 3020100
 ok 1 Read same data
 Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
 [PASS]
 ok 1 hugepage-mremap

After patch:
 running ./hugepage-mremap
 -------------------------
 TAP version 13
 1..1
  Map haddr: Returned address is 0x7eaa40000000
  Map daddr: Returned address is 0x7daa40000000
  Map vaddr: Returned address is 0x7faa40000000
  Registered memory at address 0x7eaa40000000 with userfaultfd
  Mremap: Returned address is 0x7faa40000000
  First hex is 0
  First hex is 3020100
 ok 1 Read same data
 Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
 [PASS]
 ok 1 hugepage-mremap

Link: https://lkml.kernel.org/r/da7ec96ee85ccfdb9bec704c6dd534b419212f94.1773305677.git.sayalip@linux.ibm.com
Fixes: 12b613206474 ("mm, hugepages: add hugetlb vma mremap() test")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/hugepage-mremap.c |   21 ++++-------------
 1 file changed, 5 insertions(+), 16 deletions(-)

--- a/tools/testing/selftests/mm/hugepage-mremap.c~selftest-mm-register-existing-mapping-with-userfaultfd-in-hugepage-mremap
+++ a/tools/testing/selftests/mm/hugepage-mremap.c
@@ -85,25 +85,14 @@ static void register_region_with_uffd(ch
 	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1)
 		ksft_exit_fail_msg("ioctl-UFFDIO_API: %s\n", strerror(errno));
 
-	/* Create a private anonymous mapping. The memory will be
-	 * demand-zero paged--that is, not yet allocated. When we
-	 * actually touch the memory, it will be allocated via
-	 * the userfaultfd.
-	 */
-
-	addr = mmap(NULL, len, PROT_READ | PROT_WRITE,
-		    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-	if (addr == MAP_FAILED)
-		ksft_exit_fail_msg("mmap: %s\n", strerror(errno));
-
-	ksft_print_msg("Address returned by mmap() = %p\n", addr);
-
-	/* Register the memory range of the mapping we just created for
-	 * handling by the userfaultfd object. In mode, we request to track
-	 * missing pages (i.e., pages that have not yet been faulted in).
+	/* Register the passed memory range for handling by the userfaultfd object.
+	 * In mode, we request to track missing pages
+	 * (i.e., pages that have not yet been faulted in).
 	 */
 	if (uffd_register(uffd, addr, len, true, false, false))
 		ksft_exit_fail_msg("ioctl-UFFDIO_REGISTER: %s\n", strerror(errno));
+
+	ksft_print_msg("Registered memory at address %p with userfaultfd\n", addr);
 }
 
 int main(int argc, char *argv[])
_

Patches currently in -mm which might be from sayalip@linux.ibm.com are

a.patch
selftests-mm-ensure-destination-is-hugetlb-backed-in-hugepage-mremap.patch
selftests-mm-skip-uffd-wp-mremap-if-uffd-write-protect-is-unsupported.patch
selftests-mm-skip-uffd-stress-test-when-nr_pages_per_cpu-is-zero.patch
selftests-mm-fix-double-increment-in-linked-list-cleanup-in-compaction_test.patch
selftests-mm-move-hwpoison-setup-into-run_test-and-silence-modprobe-output-for-memory-failure-category.patch
selftests-cgroup-extend-test_hugetlb_memcgc-to-support-all-huge-page-sizes.patch