+ selftest-mm-adjust-hugepage-mremap-test-size-for-large-huge-pages.patch added to mm-new branch

+ selftest-mm-adjust-hugepage-mremap-test-size-for-large-huge-pages.patch added to mm-new branch

[Andrew Morton]

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The patch titled
     Subject: selftest/mm: adjust hugepage-mremap test size for large huge pages
has been added to the -mm mm-new branch.  Its filename is
     selftest-mm-adjust-hugepage-mremap-test-size-for-large-huge-pages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftest-mm-adjust-hugepage-mremap-test-size-for-large-huge-pages.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.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Sayali Patil <sayalip@linux.ibm.com>
Subject: selftest/mm: adjust hugepage-mremap test size for large huge pages
Date: Tue, 10 Mar 2026 15:19:24 +0530

The hugepage-mremap selftest uses a default size of 10MB, which is
sufficient for small huge page sizes.  However, when the huge page size is
large (e.g.  1GB), 10MB is smaller than a single huge page.  As a result,
the test does not trigger PMD sharing and the corresponding unshare path
in mremap(), causing the test to fail (mremap succeeds where a failure is
expected).

Update run_vmtest.sh to use twice the huge page size when the huge page
size exceeds 10MB, while retaining the 10MB default for smaller huge
pages.  This ensures the test exercises the intended PMD sharing and
unsharing paths for larger huge page sizes.

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() = 0x7fffaa600000
  Mremap: Returned address is 0x7faa40000000
  First hex is 0
  First hex is 3020100
 Bail out! mremap: Expected failure, but call succeeded
 Planned tests != run tests (1 != 0)
 Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
 [FAIL]
 not ok 1 hugepage-mremap # exit=1

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() = 0x7fffaa600000
  Mremap: Returned address is 0x7faa40000000
  First hex is 0
  First hex is 3020100
 Bail out! mremap: Expected failure, but call succeeded
 Planned tests != run tests (1 != 0)
 Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0
 [FAIL]
 not ok 1 hugepage-mremap # exit=1

After patch:
 running ./hugepage-mremap 2048
 ------------------------------
 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() = 0x7fff13000000
  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 2048

Link: https://lkml.kernel.org/r/a5fc759e5896898bf930382f4a353771f4249204.1773134177.git.sayalip@linux.ibm.com
Fixes: f77a286de48c ("mm, hugepages: make memory size variable in hugepage-mremap selftest")
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 <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
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/run_vmtests.sh |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- a/tools/testing/selftests/mm/run_vmtests.sh~selftest-mm-adjust-hugepage-mremap-test-size-for-large-huge-pages
+++ a/tools/testing/selftests/mm/run_vmtests.sh
@@ -293,7 +293,18 @@ echo "$shmmax" > /proc/sys/kernel/shmmax
 echo "$shmall" > /proc/sys/kernel/shmall
 
 CATEGORY="hugetlb" run_test ./map_hugetlb
-CATEGORY="hugetlb" run_test ./hugepage-mremap
+
+# If the huge page size is larger than 10MB, increase the test memory size
+# to twice the huge page size (in MB) to ensure the test exercises PMD sharing
+# and the unshare path in hugepage-mremap. Otherwise, run the test with
+# the default 10MB memory size.
+if [ "$hpgsize_KB" -gt 10240 ]; then
+	len_mb=$(( (2 * hpgsize_KB) / 1024 ))
+	CATEGORY="hugetlb" run_test ./hugepage-mremap "${len_mb}"
+else
+	CATEGORY="hugetlb" run_test ./hugepage-mremap
+fi
+
 CATEGORY="hugetlb" run_test ./hugepage-vmemmap
 CATEGORY="hugetlb" run_test ./hugetlb-madvise
 CATEGORY="hugetlb" run_test ./hugetlb_dio
_

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

selftests-mm-restore-default-nr_hugepages-value-during-cleanup-in-charge_reserved_hugetlbsh.patch
selftests-mm-fix-hugetlb-pathname-construction-in-charge_reserved_hugetlbsh.patch
selftests-mm-fix-hugetlb-pathname-construction-in-hugetlb_reparenting_testsh.patch
selftest-mm-fix-cgroup-task-placement-and-tolerance-in-hugetlb_reparenting_testsh.patch
selftests-mm-size-tmpfs-according-to-pmd-page-size-in-split_huge_page_test.patch
selftest-mm-adjust-hugepage-mremap-test-size-for-large-huge-pages.patch
selftest-mm-register-existing-mapping-with-userfaultfd-in-hugepage-mremap.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