[PATCH 00/13] selftests/mm: fix failures and robustness improvements

[PATCH 00/13] selftests/mm: fix failures and robustness improvements

[Sayali Patil]

Hi all,

Powerpc systems with a 64K base page size exposed several issues while
running mm selftests. Some tests assume specific hugetlb configurations,
use incorrect interfaces, or fail instead of skipping when the required
kernel features are not available.

This series fixes these issues and improves test robustness.

Please review the patches and provide any feedback or suggestions for
improvement.

Thanks,
Sayali

Sayali Patil (13):
  selftests/mm: restore default nr_hugepages value during cleanup in
    charge_reserved_hugetlb.sh
  selftests/mm: fix hugetlb pathname construction in
    charge_reserved_hugetlb.sh
  selftests/mm: fix hugetlb pathname construction in
    hugetlb_reparenting_test.sh
  selftest/mm: fix cgroup task placement and tolerance in
    hugetlb_reparenting_test.sh
  selftests/mm: size tmpfs according to PMD page size in
    split_huge_page_test
  selftest/mm: adjust hugepage-mremap test size for large huge pages
  selftest/mm: register existing mapping with userfaultfd in
    hugepage-mremap
  selftests/mm: ensure destination is hugetlb-backed in hugepage-mremap
  selftests/mm: skip uffd-wp-mremap if UFFD write-protect is unsupported
  selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero
  selftests/mm: fix double increment in linked list cleanup in
    compaction_test
  selftests/mm: move hwpoison setup into run_test() and silence modprobe
    output for memory-failure category
  selftests/cgroup: extend test_hugetlb_memcg.c to support all huge page
    sizes

 .../selftests/cgroup/test_hugetlb_memcg.c     | 66 ++++++++++++++-----
 .../selftests/mm/charge_reserved_hugetlb.sh   | 44 +++++++++----
 tools/testing/selftests/mm/compaction_test.c  |  3 -
 tools/testing/selftests/mm/hugepage-mremap.c  | 25 ++-----
 .../selftests/mm/hugetlb_reparenting_test.sh  | 31 +++++----
 tools/testing/selftests/mm/run_vmtests.sh     | 59 +++++++++++------
 .../selftests/mm/split_huge_page_test.c       |  5 +-
 tools/testing/selftests/mm/uffd-stress.c      |  6 +-
 tools/testing/selftests/mm/uffd-wp-mremap.c   | 13 ++++
 .../testing/selftests/mm/write_to_hugetlbfs.c |  5 +-
 10 files changed, 169 insertions(+), 88 deletions(-)

-- 
2.52.0

[PATCH 01/13] selftests/mm: restore default nr_hugepages value during cleanup in charge_reserved_hugetlb.sh

[Sayali Patil]

During cleanup, the value of /proc/sys/vm/nr_hugepages is currently being
set to 0.  At the end of the test, if all tests pass, the original
nr_hugepages value is restored.  However, if any test fails, it remains
set to 0.
With this patch, we ensure that the original nr_hugepages value is
restored during cleanup, regardless of whether the test passes or fails.

Fixes: 7d695b1c3695b ("selftests/mm: save and restore nr_hugepages value")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/charge_reserved_hugetlb.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
index 447769657634..c9fe68b6fcf9 100755
--- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
+++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
@@ -65,7 +65,7 @@ function cleanup() {
   if [[ -e $cgroup_path/hugetlb_cgroup_test2 ]]; then
     rmdir $cgroup_path/hugetlb_cgroup_test2
   fi
-  echo 0 >/proc/sys/vm/nr_hugepages
+  echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
   echo CLEANUP DONE
 }
 
-- 
2.52.0

Re: [PATCH 01/13] selftests/mm: restore default nr_hugepages value during cleanup in charge_reserved_hugetlb.sh

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> During cleanup, the value of /proc/sys/vm/nr_hugepages is currently being
> set to 0.  At the end of the test, if all tests pass, the original
> nr_hugepages value is restored.  However, if any test fails, it remains
> set to 0.
> With this patch, we ensure that the original nr_hugepages value is
> restored during cleanup, regardless of whether the test passes or fails.
>
> Fixes: 7d695b1c3695b ("selftests/mm: save and restore nr_hugepages value")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/charge_reserved_hugetlb.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 02/13] selftests/mm: fix hugetlb pathname construction in charge_reserved_hugetlb.sh

[Sayali Patil]

The charge_reserved_hugetlb.sh script assumes hugetlb cgroup memory
interface file names use the "<size>MB" format
(e.g. hugetlb.1024MB.current).
This assumption breaks on systems with larger huge pages such as 1GB,
where the kernel exposes normalized units:
    hugetlb.1GB.current
    hugetlb.1GB.max
    hugetlb.1GB.rsvd.max
    ...

As a result, the script attempts to access files like
hugetlb.1024MB.current, which do not exist when the kernel reports the
size in GB.

Normalize the huge page size and construct the pathname using the
appropriate unit (MB or GB), matching the hugetlb controller naming.

Fixes: 209376ed2a84 ("selftests/vm: make charge_reserved_hugetlb.sh work with existing cgroup setting")
Fixes: 29750f71a9b4 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 .../selftests/mm/charge_reserved_hugetlb.sh   | 42 +++++++++++++------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
index c9fe68b6fcf9..6bec53e16e05 100755
--- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
+++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
@@ -89,6 +89,15 @@ function get_machine_hugepage_size() {
 }
 
 MB=$(get_machine_hugepage_size)
+if (( MB >= 1024 )); then
+        # For 1GB hugepages
+        UNIT="GB"
+        MB_DISPLAY=$((MB / 1024))
+else
+        # For 2MB hugepages
+        UNIT="MB"
+        MB_DISPLAY=$MB
+fi
 
 function setup_cgroup() {
   local name="$1"
@@ -98,11 +107,12 @@ function setup_cgroup() {
   mkdir $cgroup_path/$name
 
   echo writing cgroup limit: "$cgroup_limit"
-  echo "$cgroup_limit" >$cgroup_path/$name/hugetlb.${MB}MB.$fault_limit_file
+  echo "$cgroup_limit" > \
+	  $cgroup_path/$name/hugetlb.${MB_DISPLAY}${UNIT}.$fault_limit_file
 
   echo writing reservation limit: "$reservation_limit"
   echo "$reservation_limit" > \
-    $cgroup_path/$name/hugetlb.${MB}MB.$reservation_limit_file
+    $cgroup_path/$name/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_limit_file
 
   if [ -e "$cgroup_path/$name/cpuset.cpus" ]; then
     echo 0 >$cgroup_path/$name/cpuset.cpus
@@ -137,7 +147,7 @@ function wait_for_file_value() {
 
 function wait_for_hugetlb_memory_to_get_depleted() {
   local cgroup="$1"
-  local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file"
+  local path="$cgroup_path/$cgroup/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_usage_file"
 
   wait_for_file_value "$path" "0"
 }
@@ -145,7 +155,7 @@ function wait_for_hugetlb_memory_to_get_depleted() {
 function wait_for_hugetlb_memory_to_get_reserved() {
   local cgroup="$1"
   local size="$2"
-  local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file"
+  local path="$cgroup_path/$cgroup/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_usage_file"
 
   wait_for_file_value "$path" "$size"
 }
@@ -153,7 +163,7 @@ function wait_for_hugetlb_memory_to_get_reserved() {
 function wait_for_hugetlb_memory_to_get_written() {
   local cgroup="$1"
   local size="$2"
-  local path="$cgroup_path/$cgroup/hugetlb.${MB}MB.$fault_usage_file"
+  local path="$cgroup_path/$cgroup/hugetlb.${MB_DISPLAY}${UNIT}.$fault_usage_file"
 
   wait_for_file_value "$path" "$size"
 }
@@ -175,8 +185,8 @@ function write_hugetlbfs_and_get_usage() {
   hugetlb_difference=0
   reserved_difference=0
 
-  local hugetlb_usage=$cgroup_path/$cgroup/hugetlb.${MB}MB.$fault_usage_file
-  local reserved_usage=$cgroup_path/$cgroup/hugetlb.${MB}MB.$reservation_usage_file
+  local hugetlb_usage=$cgroup_path/$cgroup/hugetlb.${MB_DISPLAY}${UNIT}.$fault_usage_file
+  local reserved_usage=$cgroup_path/$cgroup/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_usage_file
 
   local hugetlb_before=$(cat $hugetlb_usage)
   local reserved_before=$(cat $reserved_usage)
@@ -307,8 +317,10 @@ function run_test() {
 
   cleanup_hugetlb_memory "hugetlb_cgroup_test"
 
-  local final_hugetlb=$(cat $cgroup_path/hugetlb_cgroup_test/hugetlb.${MB}MB.$fault_usage_file)
-  local final_reservation=$(cat $cgroup_path/hugetlb_cgroup_test/hugetlb.${MB}MB.$reservation_usage_file)
+  local final_hugetlb=$(cat \
+	 $cgroup_path/hugetlb_cgroup_test/hugetlb.${MB_DISPLAY}${UNIT}.$fault_usage_file)
+  local final_reservation=$(cat \
+	  $cgroup_path/hugetlb_cgroup_test/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_usage_file)
 
   echo $hugetlb_difference
   echo $reserved_difference
@@ -364,10 +376,14 @@ function run_multiple_cgroup_test() {
   reservation_failed1=$reservation_failed
   oom_killed1=$oom_killed
 
-  local cgroup1_hugetlb_usage=$cgroup_path/hugetlb_cgroup_test1/hugetlb.${MB}MB.$fault_usage_file
-  local cgroup1_reservation_usage=$cgroup_path/hugetlb_cgroup_test1/hugetlb.${MB}MB.$reservation_usage_file
-  local cgroup2_hugetlb_usage=$cgroup_path/hugetlb_cgroup_test2/hugetlb.${MB}MB.$fault_usage_file
-  local cgroup2_reservation_usage=$cgroup_path/hugetlb_cgroup_test2/hugetlb.${MB}MB.$reservation_usage_file
+  local cgroup1_hugetlb_usage=\
+	  $cgroup_path/hugetlb_cgroup_test1/hugetlb.${MB_DISPLAY}${UNIT}.$fault_usage_file
+  local cgroup1_reservation_usage=\
+	  $cgroup_path/hugetlb_cgroup_test1/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_usage_file
+  local cgroup2_hugetlb_usage=\
+	  $cgroup_path/hugetlb_cgroup_test2/hugetlb.${MB_DISPLAY}${UNIT}.$fault_usage_file
+  local cgroup2_reservation_usage=\
+	  $cgroup_path/hugetlb_cgroup_test2/hugetlb.${MB_DISPLAY}${UNIT}.$reservation_usage_file
 
   local usage_before_second_write=$(cat $cgroup1_hugetlb_usage)
   local reservation_usage_before_second_write=$(cat $cgroup1_reservation_usage)
-- 
2.52.0

Re: [PATCH 02/13] selftests/mm: fix hugetlb pathname construction in charge_reserved_hugetlb.sh

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> The charge_reserved_hugetlb.sh script assumes hugetlb cgroup memory
> interface file names use the "<size>MB" format
> (e.g. hugetlb.1024MB.current).
> This assumption breaks on systems with larger huge pages such as 1GB,
> where the kernel exposes normalized units:
>     hugetlb.1GB.current
>     hugetlb.1GB.max
>     hugetlb.1GB.rsvd.max
>     ...
>
> As a result, the script attempts to access files like
> hugetlb.1024MB.current, which do not exist when the kernel reports the
> size in GB.
>
> Normalize the huge page size and construct the pathname using the
> appropriate unit (MB or GB), matching the hugetlb controller naming.
>
> Fixes: 209376ed2a84 ("selftests/vm: make charge_reserved_hugetlb.sh work with existing cgroup setting")
> Fixes: 29750f71a9b4 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  .../selftests/mm/charge_reserved_hugetlb.sh   | 42 +++++++++++++------
>  1 file changed, 29 insertions(+), 13 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
> index c9fe68b6fcf9..6bec53e16e05 100755
> --- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
> +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
> @@ -89,6 +89,15 @@ function get_machine_hugepage_size() {
>  }
>
>  MB=$(get_machine_hugepage_size)
> +if (( MB >= 1024 )); then
> +        # For 1GB hugepages
> +        UNIT="GB"
> +        MB_DISPLAY=$((MB / 1024))
> +else
> +        # For 2MB hugepages
> +        UNIT="MB"
> +        MB_DISPLAY=$MB
> +fi
>
>  function setup_cgroup() {
>    local name="$1"
> @@ -98,11 +107,12 @@ function setup_cgroup() {
>    mkdir $cgroup_path/$name
>
>    echo writing cgroup limit: "$cgroup_limit"
> -  echo "$cgroup_limit" >$cgroup_path/$name/hugetlb.${MB}MB.$fault_limit_file
> +  echo "$cgroup_limit" > \
> +	  $cgroup_path/$name/hugetlb.${MB_DISPLAY}${UNIT}.$fault_limit_file

MB_DISPLAY and UNIT always show up together, maybe just use a single variable
instead. But feel free to ignore this. Anyway,

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 03/13] selftests/mm: fix hugetlb pathname construction in hugetlb_reparenting_test.sh

[Sayali Patil]

The hugetlb_reparenting_test.sh script constructs hugetlb cgroup
memory interface file names based on the configured huge page size. The
script formats the size only in MB units, which causes mismatches on
systems using larger huge pages where the kernel exposes normalized
units (e.g. "1GB" instead of "1024MB").

As a result, the test fails to locate the corresponding cgroup files
when 1GB huge pages are configured.

Update the script to detect the huge page size and select the
appropriate unit (MB or GB) so that the constructed paths match the
kernel's hugetlb controller naming.

Also print an explicit "Fail" message when a test failure occurs to
improve result visibility.

Fixes: e487a5d513cb ("selftest/mm: make hugetlb_reparenting_test tolerant to async reparenting")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 .../selftests/mm/hugetlb_reparenting_test.sh       | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
index 0dd31892ff67..073a71fa36b4 100755
--- a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
+++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
@@ -46,6 +46,13 @@ function get_machine_hugepage_size() {
 }
 
 MB=$(get_machine_hugepage_size)
+if (( MB >= 1024 )); then
+  UNIT="GB"
+  MB_DISPLAY=$((MB / 1024))
+else
+  UNIT="MB"
+  MB_DISPLAY=$MB
+fi
 
 function cleanup() {
   echo cleanup
@@ -87,6 +94,7 @@ function assert_with_retry() {
     if [[ $elapsed -ge $timeout ]]; then
       echo "actual = $((${actual%% *} / 1024 / 1024)) MB"
       echo "expected = $((${expected%% *} / 1024 / 1024)) MB"
+      echo FAIL
       cleanup
       exit 1
     fi
@@ -107,11 +115,13 @@ function assert_state() {
   fi
 
   assert_with_retry "$CGROUP_ROOT/a/memory.$usage_file" "$expected_a"
-  assert_with_retry "$CGROUP_ROOT/a/hugetlb.${MB}MB.$usage_file" "$expected_a_hugetlb"
+  assert_with_retry \
+	  "$CGROUP_ROOT/a/hugetlb.${MB_DISPLAY}${UNIT}.$usage_file" "$expected_a_hugetlb"
 
   if [[ -n "$expected_b" && -n "$expected_b_hugetlb" ]]; then
     assert_with_retry "$CGROUP_ROOT/a/b/memory.$usage_file" "$expected_b"
-    assert_with_retry "$CGROUP_ROOT/a/b/hugetlb.${MB}MB.$usage_file" "$expected_b_hugetlb"
+    assert_with_retry \
+	  "$CGROUP_ROOT/a/b/hugetlb.${MB_DISPLAY}${UNIT}.$usage_file" "$expected_b_hugetlb"
   fi
 }
 
-- 
2.52.0

Re: [PATCH 03/13] selftests/mm: fix hugetlb pathname construction in hugetlb_reparenting_test.sh

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> The hugetlb_reparenting_test.sh script constructs hugetlb cgroup
> memory interface file names based on the configured huge page size. The
> script formats the size only in MB units, which causes mismatches on
> systems using larger huge pages where the kernel exposes normalized
> units (e.g. "1GB" instead of "1024MB").
>
> As a result, the test fails to locate the corresponding cgroup files
> when 1GB huge pages are configured.
>
> Update the script to detect the huge page size and select the
> appropriate unit (MB or GB) so that the constructed paths match the
> kernel's hugetlb controller naming.
>
> Also print an explicit "Fail" message when a test failure occurs to
> improve result visibility.
>
> Fixes: e487a5d513cb ("selftest/mm: make hugetlb_reparenting_test tolerant to async reparenting")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  .../selftests/mm/hugetlb_reparenting_test.sh       | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 04/13] selftest/mm: fix cgroup task placement and tolerance in hugetlb_reparenting_test.sh

[Sayali Patil]

Launch write_to_hugetlbfs as a separate process and move only its PID
into the target cgroup before waiting for completion. This avoids moving
the test shell itself, prevents unintended charging to the shell, and
ensures hugetlb and memcg accounting is attributed only to the intended
workload.

Add a short delay before the hugetlb allocation to avoid a race where
memory may be charged before the task migration takes effect, which
can lead to incorrect accounting and intermittent test failures.

Also increase the assert_with_retry() tolerance from 7MB to 8MB. With
MEMCG_CHARGE_BATCH=64U and a 64K base page size, per-CPU batching can
result in up to 8MB of temporary charge being attributed to the parent.
The previous 7MB threshold could be exceeded, causing false failures;
raise the limit to cover the maximum expected batched charge.

Fixes: 29750f71a9b4 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 .../selftests/mm/hugetlb_reparenting_test.sh    | 17 ++++++++---------
 tools/testing/selftests/mm/write_to_hugetlbfs.c |  5 ++++-
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
index 073a71fa36b4..9c79ad69e4c6 100755
--- a/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
+++ b/tools/testing/selftests/mm/hugetlb_reparenting_test.sh
@@ -70,7 +70,7 @@ function cleanup() {
 function assert_with_retry() {
   local actual_path="$1"
   local expected="$2"
-  local tolerance=$((7 * 1024 * 1024))
+  local tolerance=$((8 * 1024 * 1024))
   local timeout=20
   local interval=1
   local start_time
@@ -153,18 +153,17 @@ write_hugetlbfs() {
   local size="$3"
 
   if [[ $cgroup2 ]]; then
-    echo $$ >$CGROUP_ROOT/$cgroup/cgroup.procs
+    cg_file="$CGROUP_ROOT/$cgroup/cgroup.procs"
   else
     echo 0 >$CGROUP_ROOT/$cgroup/cpuset.mems
     echo 0 >$CGROUP_ROOT/$cgroup/cpuset.cpus
-    echo $$ >"$CGROUP_ROOT/$cgroup/tasks"
-  fi
-  ./write_to_hugetlbfs -p "$path" -s "$size" -m 0 -o
-  if [[ $cgroup2 ]]; then
-    echo $$ >$CGROUP_ROOT/cgroup.procs
-  else
-    echo $$ >"$CGROUP_ROOT/tasks"
+    cg_file="$CGROUP_ROOT/$cgroup/tasks"
   fi
+
+  # Spawn write_to_hugetlbfs in a separate task to ensure correct cgroup accounting
+  ./write_to_hugetlbfs -p "$path" -s "$size" -m 0 -o -d & pid=$!
+  echo "$pid" > "$cg_file"
+  wait "$pid"
   echo
 }
 
diff --git a/tools/testing/selftests/mm/write_to_hugetlbfs.c b/tools/testing/selftests/mm/write_to_hugetlbfs.c
index ecb5f7619960..6b01b0485bd0 100644
--- a/tools/testing/selftests/mm/write_to_hugetlbfs.c
+++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c
@@ -83,7 +83,7 @@ int main(int argc, char **argv)
 	setvbuf(stdout, NULL, _IONBF, 0);
 	self = argv[0];
 
-	while ((c = getopt(argc, argv, "s:p:m:owlrn")) != -1) {
+	while ((c = getopt(argc, argv, "s:p:m:owlrnd")) != -1) {
 		switch (c) {
 		case 's':
 			if (sscanf(optarg, "%zu", &size) != 1) {
@@ -118,6 +118,9 @@ int main(int argc, char **argv)
 		case 'n':
 			reserve = 0;
 			break;
+		case 'd':
+			sleep(1);
+			break;
 		default:
 			errno = EINVAL;
 			perror("Invalid arg");
-- 
2.52.0

[PATCH 05/13] selftests/mm: size tmpfs according to PMD page size in split_huge_page_test

[Sayali Patil]

The split_file_backed_thp() test mounts a tmpfs with a fixed size of
"4m". This works on systems with smaller PMD page sizes,
but fails on configurations where the PMD huge page size is
larger (e.g. 16MB).

On such systems, the fixed 4MB tmpfs is insufficient to allocate even
a single PMD-sized THP, causing the test to fail.

Fix this by sizing the tmpfs dynamically based on the runtime
pmd_pagesize, allocating space for two PMD-sized pages.

Before patch:
  running ./split_huge_page_test /tmp/xfs_dir_YTrI5E
  --------------------------------------------------
  TAP version 13
  1..55
  ok 1 Split zero filled huge pages successful
  ok 2 Split huge pages to order 0 successful
  ok 3 Split huge pages to order 2 successful
  ok 4 Split huge pages to order 3 successful
  ok 5 Split huge pages to order 4 successful
  ok 6 Split huge pages to order 5 successful
  ok 7 Split huge pages to order 6 successful
  ok 8 Split huge pages to order 7 successful
  ok 9 Split PTE-mapped huge pages successful
   Please enable pr_debug in split_huge_pages_in_file() for more info.
   Failed to write data to testing file: Success (0)
  Bail out! Error occurred
   Planned tests != run tests (55 != 9)
   Totals: pass:9 fail:0 xfail:0 xpass:0 skip:0 error:0
 [FAIL]

After patch:
  --------------------------------------------------
  running ./split_huge_page_test /tmp/xfs_dir_bMvj6o
  --------------------------------------------------
  TAP version 13
  1..55
  ok 1 Split zero filled huge pages successful
  ok 2 Split huge pages to order 0 successful
  ok 3 Split huge pages to order 2 successful
  ok 4 Split huge pages to order 3 successful
  ok 5 Split huge pages to order 4 successful
  ok 6 Split huge pages to order 5 successful
  ok 7 Split huge pages to order 6 successful
  ok 8 Split huge pages to order 7 successful
  ok 9 Split PTE-mapped huge pages successful
   Please enable pr_debug in split_huge_pages_in_file() for more info.
   Please check dmesg for more information
  ok 10 File-backed THP split to order 0 test done
   Please enable pr_debug in split_huge_pages_in_file() for more info.
   Please check dmesg for more information
  ok 11 File-backed THP split to order 1 test done
   Please enable pr_debug in split_huge_pages_in_file() for more info.
   Please check dmesg for more information
  ok 12 File-backed THP split to order 2 test done
...
  ok 55 Split PMD-mapped pagecache folio to order 7 at
    in-folio offset 128 passed
   Totals: pass:55 fail:0 xfail:0 xpass:0 skip:0 error:0
   [PASS]
ok 1 split_huge_page_test /tmp/xfs_dir_bMvj6o

Fixes: fbe37501b252 ("mm: huge_memory: debugfs for file-backed THP split")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/split_huge_page_test.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index e0167111bdd1..57e8a1c9647a 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -484,6 +484,8 @@ static void split_file_backed_thp(int order)
 	char tmpfs_template[] = "/tmp/thp_split_XXXXXX";
 	const char *tmpfs_loc = mkdtemp(tmpfs_template);
 	char testfile[INPUT_MAX];
+	unsigned long size = 2 * pmd_pagesize;
+	char opts[64];
 	ssize_t num_written, num_read;
 	char *file_buf1, *file_buf2;
 	uint64_t pgoff_start = 0, pgoff_end = 1024;
@@ -503,7 +505,8 @@ static void split_file_backed_thp(int order)
 		file_buf1[i] = (char)i;
 	memset(file_buf2, 0, pmd_pagesize);
 
-	status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=always,size=4m");
+	snprintf(opts, sizeof(opts), "huge=always,size=%lu", size);
+	status = mount("tmpfs", tmpfs_loc, "tmpfs", 0, opts);
 
 	if (status)
 		ksft_exit_fail_msg("Unable to create a tmpfs for testing\n");
-- 
2.52.0

Re: [PATCH 05/13] selftests/mm: size tmpfs according to PMD page size in split_huge_page_test

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> The split_file_backed_thp() test mounts a tmpfs with a fixed size of
> "4m". This works on systems with smaller PMD page sizes,
> but fails on configurations where the PMD huge page size is
> larger (e.g. 16MB).
>
> On such systems, the fixed 4MB tmpfs is insufficient to allocate even
> a single PMD-sized THP, causing the test to fail.
>
> Fix this by sizing the tmpfs dynamically based on the runtime
> pmd_pagesize, allocating space for two PMD-sized pages.
>
> Before patch:
>   running ./split_huge_page_test /tmp/xfs_dir_YTrI5E
>   --------------------------------------------------
>   TAP version 13
>   1..55
>   ok 1 Split zero filled huge pages successful
>   ok 2 Split huge pages to order 0 successful
>   ok 3 Split huge pages to order 2 successful
>   ok 4 Split huge pages to order 3 successful
>   ok 5 Split huge pages to order 4 successful
>   ok 6 Split huge pages to order 5 successful
>   ok 7 Split huge pages to order 6 successful
>   ok 8 Split huge pages to order 7 successful
>   ok 9 Split PTE-mapped huge pages successful
>    Please enable pr_debug in split_huge_pages_in_file() for more info.
>    Failed to write data to testing file: Success (0)
>   Bail out! Error occurred
>    Planned tests != run tests (55 != 9)
>    Totals: pass:9 fail:0 xfail:0 xpass:0 skip:0 error:0
>  [FAIL]
>
> After patch:
>   --------------------------------------------------
>   running ./split_huge_page_test /tmp/xfs_dir_bMvj6o
>   --------------------------------------------------
>   TAP version 13
>   1..55
>   ok 1 Split zero filled huge pages successful
>   ok 2 Split huge pages to order 0 successful
>   ok 3 Split huge pages to order 2 successful
>   ok 4 Split huge pages to order 3 successful
>   ok 5 Split huge pages to order 4 successful
>   ok 6 Split huge pages to order 5 successful
>   ok 7 Split huge pages to order 6 successful
>   ok 8 Split huge pages to order 7 successful
>   ok 9 Split PTE-mapped huge pages successful
>    Please enable pr_debug in split_huge_pages_in_file() for more info.
>    Please check dmesg for more information
>   ok 10 File-backed THP split to order 0 test done
>    Please enable pr_debug in split_huge_pages_in_file() for more info.
>    Please check dmesg for more information
>   ok 11 File-backed THP split to order 1 test done
>    Please enable pr_debug in split_huge_pages_in_file() for more info.
>    Please check dmesg for more information
>   ok 12 File-backed THP split to order 2 test done
> ...
>   ok 55 Split PMD-mapped pagecache folio to order 7 at
>     in-folio offset 128 passed
>    Totals: pass:55 fail:0 xfail:0 xpass:0 skip:0 error:0
>    [PASS]
> ok 1 split_huge_page_test /tmp/xfs_dir_bMvj6o
>
> Fixes: fbe37501b252 ("mm: huge_memory: debugfs for file-backed THP split")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/split_huge_page_test.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
Thanks for fixing it.

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 06/13] selftest/mm: adjust hugepage-mremap test size for large huge pages

[Sayali Patil]

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

Fixes: f77a286de48c ("mm, hugepages: make memory size variable in hugepage-mremap selftest")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/run_vmtests.sh | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index afdcfd0d7cef..7273c3e18227 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/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
-- 
2.52.0

Re: [PATCH 06/13] selftest/mm: adjust hugepage-mremap test size for large huge pages

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> 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
>
> Fixes: f77a286de48c ("mm, hugepages: make memory size variable in hugepage-mremap selftest")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/run_vmtests.sh | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>

Makes sense.

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 07/13] selftest/mm: register existing mapping with userfaultfd in hugepage-mremap

[Sayali Patil]

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

Fixes: 12b613206474 ("mm, hugepages: add hugetlb vma mremap() test")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/hugepage-mremap.c | 21 +++++---------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
index b8f7d92e5a35..e611249080d6 100644
--- a/tools/testing/selftests/mm/hugepage-mremap.c
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
@@ -85,25 +85,14 @@ static void register_region_with_uffd(char *addr, size_t len)
 	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[])
-- 
2.52.0

[PATCH 08/13] selftests/mm: ensure destination is hugetlb-backed in hugepage-mremap

[Sayali Patil]

The hugepage-mremap selftest reserves the destination address using a
anonymous base-page mapping before calling mremap() with MREMAP_FIXED,
while the source region is hugetlb-backed.

When remapping a hugetlb mapping into a base-page VMA may fail with:

    mremap: Device or resource busy

This is observed on powerpc hash MMU systems where slice constraints
and page size incompatibilities prevent the remap.

Ensure the destination region is created using MAP_HUGETLB so that both
source and destination VMAs are hugetlb-backed and compatible. Also add
MAP_POPULATE to the destination mapping to prefault hugepages,
matching the behaviour used for other hugetlb mappiing in the test and
ensuring deterministic behaviour.

This ensures the test reliably exercises hugetlb mremap instead of
failing due to VMA type mismatch.

Fixes: 12b613206474 ("mm, hugepages: add hugetlb vma mremap() test")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/hugepage-mremap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
index e611249080d6..9558515c282d 100644
--- a/tools/testing/selftests/mm/hugepage-mremap.c
+++ b/tools/testing/selftests/mm/hugepage-mremap.c
@@ -136,8 +136,8 @@ int main(int argc, char *argv[])
 		ksft_exit_fail_msg("mmap3: %s\n", strerror(errno));
 
 	suggested_addr = 0x7faa40000000;
-	void *vaddr =
-		mmap((void *)suggested_addr, length, PROTECTION, FLAGS, -1, 0);
+	void *vaddr = mmap((void *)suggested_addr, length, PROTECTION,
+			MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0);
 	ksft_print_msg("Map vaddr: Returned address is %p\n", vaddr);
 	if (vaddr == MAP_FAILED)
 		ksft_exit_fail_msg("mmap2: %s\n", strerror(errno));
-- 
2.52.0

Re: [PATCH 08/13] selftests/mm: ensure destination is hugetlb-backed in hugepage-mremap

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> The hugepage-mremap selftest reserves the destination address using a
> anonymous base-page mapping before calling mremap() with MREMAP_FIXED,
> while the source region is hugetlb-backed.
>
> When remapping a hugetlb mapping into a base-page VMA may fail with:
>
>     mremap: Device or resource busy
>
> This is observed on powerpc hash MMU systems where slice constraints
> and page size incompatibilities prevent the remap.
>
> Ensure the destination region is created using MAP_HUGETLB so that both
> source and destination VMAs are hugetlb-backed and compatible. Also add
> MAP_POPULATE to the destination mapping to prefault hugepages,
> matching the behaviour used for other hugetlb mappiing in the test and
> ensuring deterministic behaviour.
>
> This ensures the test reliably exercises hugetlb mremap instead of
> failing due to VMA type mismatch.
>
> Fixes: 12b613206474 ("mm, hugepages: add hugetlb vma mremap() test")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/hugepage-mremap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/hugepage-mremap.c b/tools/testing/selftests/mm/hugepage-mremap.c
> index e611249080d6..9558515c282d 100644
> --- a/tools/testing/selftests/mm/hugepage-mremap.c
> +++ b/tools/testing/selftests/mm/hugepage-mremap.c
> @@ -136,8 +136,8 @@ int main(int argc, char *argv[])
>  		ksft_exit_fail_msg("mmap3: %s\n", strerror(errno));
>
>  	suggested_addr = 0x7faa40000000;
> -	void *vaddr =
> -		mmap((void *)suggested_addr, length, PROTECTION, FLAGS, -1, 0);
> +	void *vaddr = mmap((void *)suggested_addr, length, PROTECTION,
> +			MAP_HUGETLB | MAP_SHARED | MAP_POPULATE, fd, 0);

FLAGS is only used here, why not change the definition of FLAGS
or remove FLAGS along with your change?

Feel free to add

Acked-by: Zi Yan <ziy@nvidia.com>

after you do either above.

Best Regards,
Yan, Zi

[PATCH 09/13] selftests/mm: skip uffd-wp-mremap if UFFD write-protect is unsupported

[Sayali Patil]

The uffd-wp-mremap test requires the UFFD_FEATURE_PAGEFAULT_FLAG_WP
capability. On systems where userfaultfd write-protect is
not supported, uffd_register() fails and the test reports failures.

Check for the required feature at startup and skip the test when the
UFFD_FEATURE_PAGEFAULT_FLAG_WP capability is not present,
preventing false failures on unsupported configurations.

Before patch:
 running ./uffd-wp-mremap
 ------------------------
  [INFO] detected THP size: 256 KiB
  [INFO] detected THP size: 512 KiB
  [INFO] detected THP size: 1024 KiB
  [INFO] detected THP size: 2048 KiB
  [INFO] detected hugetlb page size: 2048 KiB
  [INFO] detected hugetlb page size: 1048576 KiB
 1..24
  [RUN] test_one_folio(size=65536, private=false, swapout=false,
  hugetlb=false)
 not ok 1 uffd_register() failed
  [RUN] test_one_folio(size=65536, private=true, swapout=false,
  hugetlb=false)
 not ok 2 uffd_register() failed
  [RUN] test_one_folio(size=65536, private=false, swapout=true,
  hugetlb=false)
 not ok 3 uffd_register() failed
  [RUN] test_one_folio(size=65536, private=true, swapout=true,
  hugetlb=false)
 not ok 4 uffd_register() failed
  [RUN] test_one_folio(size=262144, private=false, swapout=false,
  hugetlb=false)
 not ok 5 uffd_register() failed
  [RUN] test_one_folio(size=524288, private=false, swapout=false,
  hugetlb=false)
 not ok 6 uffd_register() failed
 .
 .
 .
 Bail out! 24 out of 24 tests failed
  Totals: pass:0 fail:24 xfail:0 xpass:0 skip:0 error:0
 [FAIL]
not ok 1 uffd-wp-mremap # exit=1

After patch:
 running ./uffd-wp-mremap
 ------------------------
 1..0 # SKIP uffd-wp feature not supported
 [SKIP]
ok 1 uffd-wp-mremap # SKIP

Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/uffd-wp-mremap.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/testing/selftests/mm/uffd-wp-mremap.c b/tools/testing/selftests/mm/uffd-wp-mremap.c
index 17186d4a4147..73d53a4da389 100644
--- a/tools/testing/selftests/mm/uffd-wp-mremap.c
+++ b/tools/testing/selftests/mm/uffd-wp-mremap.c
@@ -19,6 +19,17 @@ static size_t thpsizes[20];
 static int nr_hugetlbsizes;
 static size_t hugetlbsizes[10];
 
+static void uffd_wp_feature_supported(void)
+{
+	uint64_t features;
+
+	if (uffd_get_features(&features) && errno == ENOENT)
+		ksft_exit_skip("failed to get available features (%d)\n", errno);
+
+	if (!(features & UFFD_FEATURE_PAGEFAULT_FLAG_WP))
+		ksft_exit_skip("uffd-wp feature not supported\n");
+}
+
 static int detect_thp_sizes(size_t sizes[], int max)
 {
 	int count = 0;
@@ -336,6 +347,8 @@ int main(int argc, char **argv)
 	struct thp_settings settings;
 	int i, j, plan = 0;
 
+	uffd_wp_feature_supported();
+
 	pagesize = getpagesize();
 	nr_thpsizes = detect_thp_sizes(thpsizes, ARRAY_SIZE(thpsizes));
 	nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
-- 
2.52.0

Re: [PATCH 09/13] selftests/mm: skip uffd-wp-mremap if UFFD write-protect is unsupported

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> The uffd-wp-mremap test requires the UFFD_FEATURE_PAGEFAULT_FLAG_WP
> capability. On systems where userfaultfd write-protect is
> not supported, uffd_register() fails and the test reports failures.
>
> Check for the required feature at startup and skip the test when the
> UFFD_FEATURE_PAGEFAULT_FLAG_WP capability is not present,
> preventing false failures on unsupported configurations.
>
> Before patch:
>  running ./uffd-wp-mremap
>  ------------------------
>   [INFO] detected THP size: 256 KiB
>   [INFO] detected THP size: 512 KiB
>   [INFO] detected THP size: 1024 KiB
>   [INFO] detected THP size: 2048 KiB
>   [INFO] detected hugetlb page size: 2048 KiB
>   [INFO] detected hugetlb page size: 1048576 KiB
>  1..24
>   [RUN] test_one_folio(size=65536, private=false, swapout=false,
>   hugetlb=false)
>  not ok 1 uffd_register() failed
>   [RUN] test_one_folio(size=65536, private=true, swapout=false,
>   hugetlb=false)
>  not ok 2 uffd_register() failed
>   [RUN] test_one_folio(size=65536, private=false, swapout=true,
>   hugetlb=false)
>  not ok 3 uffd_register() failed
>   [RUN] test_one_folio(size=65536, private=true, swapout=true,
>   hugetlb=false)
>  not ok 4 uffd_register() failed
>   [RUN] test_one_folio(size=262144, private=false, swapout=false,
>   hugetlb=false)
>  not ok 5 uffd_register() failed
>   [RUN] test_one_folio(size=524288, private=false, swapout=false,
>   hugetlb=false)
>  not ok 6 uffd_register() failed
>  .
>  .
>  .
>  Bail out! 24 out of 24 tests failed
>   Totals: pass:0 fail:24 xfail:0 xpass:0 skip:0 error:0
>  [FAIL]
> not ok 1 uffd-wp-mremap # exit=1
>
> After patch:
>  running ./uffd-wp-mremap
>  ------------------------
>  1..0 # SKIP uffd-wp feature not supported
>  [SKIP]
> ok 1 uffd-wp-mremap # SKIP
>
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/uffd-wp-mremap.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
LGTM.

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 10/13] selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero

[Sayali Patil]

uffd-stress currently fails when the computed nr_pages_per_cpu
evaluates to zero:

nr_pages_per_cpu = bytes / page_size / nr_parallel

This can occur on systems with large hugepage sizes (e.g. 1GB) and a
high number of CPUs, where the total allocated memory is sufficient
overall but not enough to provide at least one page per cpu.

In such cases, the failure is due to insufficient test resources
rather than incorrect kernel behaviour. Update the test
to treat this condition as a test skip instead of reporting an error.

Fixes: db0f1c138f18 ("selftests/mm: print some details when uffd-stress gets bad params")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/uffd-stress.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
index 700fbaa18d44..b8f22ea859a6 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -491,9 +491,9 @@ int main(int argc, char **argv)
 
 	gopts->nr_pages_per_cpu = bytes / gopts->page_size / gopts->nr_parallel;
 	if (!gopts->nr_pages_per_cpu) {
-		_err("pages_per_cpu = 0, cannot test (%lu / %lu / %lu)",
-			bytes, gopts->page_size, gopts->nr_parallel);
-		usage();
+		ksft_print_msg("pages_per_cpu = 0, cannot test (%lu / %lu / %lu)\n",
+			       bytes, gopts->page_size, gopts->nr_parallel);
+		return KSFT_SKIP;
 	}
 
 	bounces = atoi(argv[3]);
-- 
2.52.0

Re: [PATCH 10/13] selftests/mm: skip uffd-stress test when nr_pages_per_cpu is zero

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> uffd-stress currently fails when the computed nr_pages_per_cpu
> evaluates to zero:
>
> nr_pages_per_cpu = bytes / page_size / nr_parallel
>
> This can occur on systems with large hugepage sizes (e.g. 1GB) and a
> high number of CPUs, where the total allocated memory is sufficient
> overall but not enough to provide at least one page per cpu.
>
> In such cases, the failure is due to insufficient test resources
> rather than incorrect kernel behaviour. Update the test
> to treat this condition as a test skip instead of reporting an error.
>
> Fixes: db0f1c138f18 ("selftests/mm: print some details when uffd-stress gets bad params")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/uffd-stress.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
Makes sense.

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 11/13] selftests/mm: fix double increment in linked list cleanup in compaction_test

[Sayali Patil]

The cleanup loop of allocated memory currently uses:

    for (entry = list; entry != NULL; entry = entry->next) {
        munmap(entry->map, MAP_SIZE);
        if (!entry->next)
            break;
        entry = entry->next;
    }

The inner entry = entry->next causes the loop to skip every
other node, resulting in only half of the mapped regions being
unmapped.

Remove the redundant increment to ensure every entry is visited
and unmapped during cleanup.

Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/compaction_test.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
index 30209c40b697..f73930706bd0 100644
--- a/tools/testing/selftests/mm/compaction_test.c
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -263,9 +263,6 @@ int main(int argc, char **argv)
 
 	for (entry = list; entry != NULL; entry = entry->next) {
 		munmap(entry->map, MAP_SIZE);
-		if (!entry->next)
-			break;
-		entry = entry->next;
 	}
 
 	if (check_compaction(mem_free, hugepage_size,
-- 
2.52.0

Re: [PATCH 11/13] selftests/mm: fix double increment in linked list cleanup in compaction_test

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> The cleanup loop of allocated memory currently uses:
>
>     for (entry = list; entry != NULL; entry = entry->next) {
>         munmap(entry->map, MAP_SIZE);
>         if (!entry->next)
>             break;
>         entry = entry->next;
>     }
>
> The inner entry = entry->next causes the loop to skip every
> other node, resulting in only half of the mapped regions being
> unmapped.
>
> Remove the redundant increment to ensure every entry is visited
> and unmapped during cleanup.
>
> Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/compaction_test.c | 3 ---
>  1 file changed, 3 deletions(-)
>
Thank you for fixing it.

Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

[PATCH 12/13] selftests/mm: move hwpoison setup into run_test() and silence modprobe output for memory-failure category

[Sayali Patil]

run_vmtests.sh contains special handling to ensure the hwpoison_inject
module is available for the memory-failure tests. This logic was
implemented outside of run_test(), making the setup category-specific
but managed globally.

Move the hwpoison_inject handling into run_test() and restrict it
to the memory-failure category so that:
1. the module is checked and loaded only when memory-failure tests run,
2. the test is skipped if the module or the debugfs interface
(/sys/kernel/debug/hwpoison/) is not available.
3. the module is unloaded after the test if it was loaded by the script.

This localizes category-specific setup and makes the test flow
consistent with other per-category preparations.

While updating this logic, fix the module availability check.
The script previously used:

	modprobe -R hwpoison_inject

The -R option prints the resolved module name to stdout, causing every
run to print:

	hwpoison_inject

in the test output, even when no action is required, introducing
unnecessary noise.

Replace this with:

	modprobe -n hwpoison_inject

which verifies that the module is loadable without producing output,
keeping the selftest logs clean and consistent.

Fixes: ff4ef2fbd101 ("selftests/mm: add memory failure anonymous page test")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 tools/testing/selftests/mm/run_vmtests.sh | 46 ++++++++++++++---------
 1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 7273c3e18227..7f3a3027cd9a 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -250,6 +250,27 @@ run_test() {
 			fi
 		fi
 
+		# Ensure hwpoison_inject is available for memory-failure tests
+		if [ "${CATEGORY}" = "memory-failure" ]; then
+			# Try to load hwpoison_inject if not present.
+			HWPOISON_DIR=/sys/kernel/debug/hwpoison/
+			if [ ! -d "$HWPOISON_DIR" ]; then
+				if ! modprobe -n hwpoison_inject > /dev/null 2>&1; then
+					echo "Module hwpoison_inject not found, skipping..." \
+						| tap_prefix
+					skip=1
+				else
+					modprobe hwpoison_inject > /dev/null 2>&1
+					LOADED_MOD=1
+				fi
+			fi
+
+			if [ ! -d "$HWPOISON_DIR" ]; then
+				echo "hwpoison debugfs interface not present" | tap_prefix
+				skip=1
+			fi
+		fi
+
 		local test=$(pretty_name "$*")
 		local title="running $*"
 		local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
@@ -261,6 +282,12 @@ run_test() {
 		else
 			local ret=$ksft_skip
 		fi
+
+		# Unload hwpoison_inject if we loaded it
+		if [ -n "${LOADED_MOD}" ]; then
+			modprobe -r hwpoison_inject > /dev/null 2>&1
+		fi
+
 		count_total=$(( count_total + 1 ))
 		if [ $ret -eq 0 ]; then
 			count_pass=$(( count_pass + 1 ))
@@ -540,24 +567,7 @@ CATEGORY="page_frag" run_test ./test_page_frag.sh nonaligned
 
 CATEGORY="rmap" run_test ./rmap
 
-# Try to load hwpoison_inject if not present.
-HWPOISON_DIR=/sys/kernel/debug/hwpoison/
-if [ ! -d "$HWPOISON_DIR" ]; then
-	if ! modprobe -q -R hwpoison_inject; then
-		echo "Module hwpoison_inject not found, skipping..."
-	else
-		modprobe hwpoison_inject > /dev/null 2>&1
-		LOADED_MOD=1
-	fi
-fi
-
-if [ -d "$HWPOISON_DIR" ]; then
-	CATEGORY="memory-failure" run_test ./memory-failure
-fi
-
-if [ -n "${LOADED_MOD}" ]; then
-	modprobe -r hwpoison_inject > /dev/null 2>&1
-fi
+CATEGORY="memory-failure" run_test ./memory-failure
 
 if [ "${HAVE_HUGEPAGES}" = 1 ]; then
 	echo "$orig_nr_hugepgs" > /proc/sys/vm/nr_hugepages
-- 
2.52.0

Re: [PATCH 12/13] selftests/mm: move hwpoison setup into run_test() and silence modprobe output for memory-failure category

[Zi Yan]

On 10 Mar 2026, at 5:49, Sayali Patil wrote:

> run_vmtests.sh contains special handling to ensure the hwpoison_inject
> module is available for the memory-failure tests. This logic was
> implemented outside of run_test(), making the setup category-specific
> but managed globally.
>
> Move the hwpoison_inject handling into run_test() and restrict it
> to the memory-failure category so that:
> 1. the module is checked and loaded only when memory-failure tests run,
> 2. the test is skipped if the module or the debugfs interface
> (/sys/kernel/debug/hwpoison/) is not available.
> 3. the module is unloaded after the test if it was loaded by the script.
>
> This localizes category-specific setup and makes the test flow
> consistent with other per-category preparations.
>
> While updating this logic, fix the module availability check.
> The script previously used:
>
> 	modprobe -R hwpoison_inject
>
> The -R option prints the resolved module name to stdout, causing every
> run to print:
>
> 	hwpoison_inject
>
> in the test output, even when no action is required, introducing
> unnecessary noise.
>
> Replace this with:
>
> 	modprobe -n hwpoison_inject
>
> which verifies that the module is loadable without producing output,
> keeping the selftest logs clean and consistent.
>
> Fixes: ff4ef2fbd101 ("selftests/mm: add memory failure anonymous page test")
> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
> ---
>  tools/testing/selftests/mm/run_vmtests.sh | 46 ++++++++++++++---------
>  1 file changed, 28 insertions(+), 18 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
> index 7273c3e18227..7f3a3027cd9a 100755
> --- a/tools/testing/selftests/mm/run_vmtests.sh
> +++ b/tools/testing/selftests/mm/run_vmtests.sh
> @@ -250,6 +250,27 @@ run_test() {
>  			fi
>  		fi
>
> +		# Ensure hwpoison_inject is available for memory-failure tests
> +		if [ "${CATEGORY}" = "memory-failure" ]; then
> +			# Try to load hwpoison_inject if not present.
> +			HWPOISON_DIR=/sys/kernel/debug/hwpoison/
> +			if [ ! -d "$HWPOISON_DIR" ]; then
> +				if ! modprobe -n hwpoison_inject > /dev/null 2>&1; then
> +					echo "Module hwpoison_inject not found, skipping..." \
> +						| tap_prefix
> +					skip=1
> +				else
> +					modprobe hwpoison_inject > /dev/null 2>&1
> +					LOADED_MOD=1
> +				fi
> +			fi
> +
> +			if [ ! -d "$HWPOISON_DIR" ]; then
> +				echo "hwpoison debugfs interface not present" | tap_prefix
> +				skip=1
> +			fi
> +		fi
> +
>  		local test=$(pretty_name "$*")
>  		local title="running $*"
>  		local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
> @@ -261,6 +282,12 @@ run_test() {
>  		else
>  			local ret=$ksft_skip
>  		fi
> +
> +		# Unload hwpoison_inject if we loaded it
> +		if [ -n "${LOADED_MOD}" ]; then
> +			modprobe -r hwpoison_inject > /dev/null 2>&1
> +		fi
> +
>  		count_total=$(( count_total + 1 ))
>  		if [ $ret -eq 0 ]; then
>  			count_pass=$(( count_pass + 1 ))
> @@ -540,24 +567,7 @@ CATEGORY="page_frag" run_test ./test_page_frag.sh nonaligned
>
>  CATEGORY="rmap" run_test ./rmap
>
> -# Try to load hwpoison_inject if not present.
> -HWPOISON_DIR=/sys/kernel/debug/hwpoison/
> -if [ ! -d "$HWPOISON_DIR" ]; then
> -	if ! modprobe -q -R hwpoison_inject; then
> -		echo "Module hwpoison_inject not found, skipping..."
> -	else
> -		modprobe hwpoison_inject > /dev/null 2>&1
> -		LOADED_MOD=1
> -	fi
> -fi
> -
> -if [ -d "$HWPOISON_DIR" ]; then
> -	CATEGORY="memory-failure" run_test ./memory-failure
> -fi
> -
> -if [ -n "${LOADED_MOD}" ]; then
> -	modprobe -r hwpoison_inject > /dev/null 2>&1
> -fi
> +CATEGORY="memory-failure" run_test ./memory-failure
>
>  if [ "${HAVE_HUGEPAGES}" = 1 ]; then
>  	echo "$orig_nr_hugepgs" > /proc/sys/vm/nr_hugepages
> -- 
> 2.52.0

+Miaohe

LGTM.

Acked-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi

Re: [PATCH 12/13] selftests/mm: move hwpoison setup into run_test() and silence modprobe output for memory-failure category

[Miaohe Lin]

On 2026/3/11 3:15, Zi Yan wrote:
> On 10 Mar 2026, at 5:49, Sayali Patil wrote:
> 
>> run_vmtests.sh contains special handling to ensure the hwpoison_inject
>> module is available for the memory-failure tests. This logic was
>> implemented outside of run_test(), making the setup category-specific
>> but managed globally.
>>
>> Move the hwpoison_inject handling into run_test() and restrict it
>> to the memory-failure category so that:
>> 1. the module is checked and loaded only when memory-failure tests run,
>> 2. the test is skipped if the module or the debugfs interface
>> (/sys/kernel/debug/hwpoison/) is not available.
>> 3. the module is unloaded after the test if it was loaded by the script.
>>
>> This localizes category-specific setup and makes the test flow
>> consistent with other per-category preparations.
>>
>> While updating this logic, fix the module availability check.
>> The script previously used:
>>
>> 	modprobe -R hwpoison_inject
>>
>> The -R option prints the resolved module name to stdout, causing every
>> run to print:
>>
>> 	hwpoison_inject
>>
>> in the test output, even when no action is required, introducing
>> unnecessary noise.
>>
>> Replace this with:
>>
>> 	modprobe -n hwpoison_inject
>>
>> which verifies that the module is loadable without producing output,
>> keeping the selftest logs clean and consistent.
>>
>> Fixes: ff4ef2fbd101 ("selftests/mm: add memory failure anonymous page test")
>> Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
>> ---
>>  tools/testing/selftests/mm/run_vmtests.sh | 46 ++++++++++++++---------
>>  1 file changed, 28 insertions(+), 18 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
>> index 7273c3e18227..7f3a3027cd9a 100755
>> --- a/tools/testing/selftests/mm/run_vmtests.sh
>> +++ b/tools/testing/selftests/mm/run_vmtests.sh
>> @@ -250,6 +250,27 @@ run_test() {
>>  			fi
>>  		fi
>>
>> +		# Ensure hwpoison_inject is available for memory-failure tests
>> +		if [ "${CATEGORY}" = "memory-failure" ]; then
>> +			# Try to load hwpoison_inject if not present.
>> +			HWPOISON_DIR=/sys/kernel/debug/hwpoison/
>> +			if [ ! -d "$HWPOISON_DIR" ]; then
>> +				if ! modprobe -n hwpoison_inject > /dev/null 2>&1; then
>> +					echo "Module hwpoison_inject not found, skipping..." \
>> +						| tap_prefix
>> +					skip=1
>> +				else
>> +					modprobe hwpoison_inject > /dev/null 2>&1
>> +					LOADED_MOD=1
>> +				fi
>> +			fi
>> +
>> +			if [ ! -d "$HWPOISON_DIR" ]; then
>> +				echo "hwpoison debugfs interface not present" | tap_prefix
>> +				skip=1
>> +			fi
>> +		fi
>> +
>>  		local test=$(pretty_name "$*")
>>  		local title="running $*"
>>  		local sep=$(echo -n "$title" | tr "[:graph:][:space:]" -)
>> @@ -261,6 +282,12 @@ run_test() {
>>  		else
>>  			local ret=$ksft_skip
>>  		fi
>> +
>> +		# Unload hwpoison_inject if we loaded it
>> +		if [ -n "${LOADED_MOD}" ]; then
>> +			modprobe -r hwpoison_inject > /dev/null 2>&1
>> +		fi
>> +
>>  		count_total=$(( count_total + 1 ))
>>  		if [ $ret -eq 0 ]; then
>>  			count_pass=$(( count_pass + 1 ))
>> @@ -540,24 +567,7 @@ CATEGORY="page_frag" run_test ./test_page_frag.sh nonaligned
>>
>>  CATEGORY="rmap" run_test ./rmap
>>
>> -# Try to load hwpoison_inject if not present.
>> -HWPOISON_DIR=/sys/kernel/debug/hwpoison/
>> -if [ ! -d "$HWPOISON_DIR" ]; then
>> -	if ! modprobe -q -R hwpoison_inject; then
>> -		echo "Module hwpoison_inject not found, skipping..."
>> -	else
>> -		modprobe hwpoison_inject > /dev/null 2>&1
>> -		LOADED_MOD=1
>> -	fi
>> -fi
>> -
>> -if [ -d "$HWPOISON_DIR" ]; then
>> -	CATEGORY="memory-failure" run_test ./memory-failure
>> -fi
>> -
>> -if [ -n "${LOADED_MOD}" ]; then
>> -	modprobe -r hwpoison_inject > /dev/null 2>&1
>> -fi
>> +CATEGORY="memory-failure" run_test ./memory-failure
>>
>>  if [ "${HAVE_HUGEPAGES}" = 1 ]; then
>>  	echo "$orig_nr_hugepgs" > /proc/sys/vm/nr_hugepages
>> -- 
>> 2.52.0
> 
> +Miaohe
> 
> LGTM.
> 
> Acked-by: Zi Yan <ziy@nvidia.com>

LGTM. Thanks both.

Acked-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks.
.

[PATCH 13/13] selftests/cgroup: extend test_hugetlb_memcg.c to support all huge page sizes

[Sayali Patil]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=y, Size: 6905 bytes --]

The hugetlb memcg selftest was previously skipped when the configured
huge page size was not 2MB, preventing the test from running on systems
using other default huge page sizes.

Detect the system's configured huge page size at runtime and use it for
the allocation instead of assuming a fixed 2MB size. This allows the
test to run on configurations using non-2MB huge pages and avoids
unnecessary skips.

Fixes: c0dddb7aa5f8 ("selftests: add a selftest to verify hugetlb usage in memcg")
Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
---
 .../selftests/cgroup/test_hugetlb_memcg.c     | 66 ++++++++++++++-----
 1 file changed, 48 insertions(+), 18 deletions(-)

diff --git a/tools/testing/selftests/cgroup/test_hugetlb_memcg.c b/tools/testing/selftests/cgroup/test_hugetlb_memcg.c
index f451aa449be6..a449dbec16a8 100644
--- a/tools/testing/selftests/cgroup/test_hugetlb_memcg.c
+++ b/tools/testing/selftests/cgroup/test_hugetlb_memcg.c
@@ -12,10 +12,15 @@
 
 #define ADDR ((void *)(0x0UL))
 #define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
-/* mapping 8 MBs == 4 hugepages */
-#define LENGTH (8UL*1024*1024)
 #define PROTECTION (PROT_READ | PROT_WRITE)
 
+/*
+ * This value matches the kernel's MEMCG_CHARGE_BATCH definition:
+ * see include/linux/memcontrol.h. If the kernel value changes, this
+ * test constant must be updated accordingly to stay consistent.
+ */
+#define MEMCG_CHARGE_BATCH 64U
+
 /* borrowed from mm/hmm-tests.c */
 static long get_hugepage_size(void)
 {
@@ -84,11 +89,11 @@ static unsigned int check_first(char *addr)
 	return *(unsigned int *)addr;
 }
 
-static void write_data(char *addr)
+static void write_data(char *addr, size_t length)
 {
 	unsigned long i;
 
-	for (i = 0; i < LENGTH; i++)
+	for (i = 0; i < length; i++)
 		*(addr + i) = (char)i;
 }
 
@@ -96,26 +101,31 @@ static int hugetlb_test_program(const char *cgroup, void *arg)
 {
 	char *test_group = (char *)arg;
 	void *addr;
+	long hpage_size = get_hugepage_size() * 1024;
 	long old_current, expected_current, current;
 	int ret = EXIT_FAILURE;
+	size_t length = 4 * hpage_size;
+	int pagesize, nr_pages;
+
+	pagesize = getpagesize();
 
 	old_current = cg_read_long(test_group, "memory.current");
 	set_nr_hugepages(20);
 	current = cg_read_long(test_group, "memory.current");
-	if (current - old_current >= MB(2)) {
+	if (current - old_current >= hpage_size) {
 		ksft_print_msg(
 			"setting nr_hugepages should not increase hugepage usage.\n");
 		ksft_print_msg("before: %ld, after: %ld\n", old_current, current);
 		return EXIT_FAILURE;
 	}
 
-	addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, 0, 0);
+	addr = mmap(ADDR, length, PROTECTION, FLAGS, 0, 0);
 	if (addr == MAP_FAILED) {
 		ksft_print_msg("fail to mmap.\n");
 		return EXIT_FAILURE;
 	}
 	current = cg_read_long(test_group, "memory.current");
-	if (current - old_current >= MB(2)) {
+	if (current - old_current >= hpage_size) {
 		ksft_print_msg("mmap should not increase hugepage usage.\n");
 		ksft_print_msg("before: %ld, after: %ld\n", old_current, current);
 		goto out_failed_munmap;
@@ -124,10 +134,24 @@ static int hugetlb_test_program(const char *cgroup, void *arg)
 
 	/* read the first page */
 	check_first(addr);
-	expected_current = old_current + MB(2);
+	nr_pages = hpage_size / pagesize;
+	expected_current = old_current + hpage_size;
 	current = cg_read_long(test_group, "memory.current");
-	if (!values_close(expected_current, current, 5)) {
-		ksft_print_msg("memory usage should increase by around 2MB.\n");
+	if (nr_pages < MEMCG_CHARGE_BATCH && current == old_current) {
+		/*
+		 * Memory cgroup charging uses per-CPU stocks and batched updates to the
+		 *  memcg usage counters. For hugetlb allocations, the number of pages
+		 *  that memcg charges is expressed in base pages (nr_pages), not
+		 *  in hugepage units. When the charge for an allocation is smaller than
+		 *  the internal batching threshold  (nr_pages <  MEMCG_CHARGE_BATCH),
+		 *  it may be fully satisfied from the CPU’s local stock. In such
+		 *  cases memory.current does not necessarily
+		 *  increase.
+		 *  Therefore, Treat a zero delta as valid behaviour here.
+		 */
+		ksft_print_msg("no visible memcg charge, allocation consumed from local stock.\n");
+	} else if (!values_close(expected_current, current, 5)) {
+		ksft_print_msg("memory usage should increase by ~1 huge page.\n");
 		ksft_print_msg(
 			"expected memory: %ld, actual memory: %ld\n",
 			expected_current, current);
@@ -135,11 +159,11 @@ static int hugetlb_test_program(const char *cgroup, void *arg)
 	}
 
 	/* write to the whole range */
-	write_data(addr);
+	write_data(addr, length);
 	current = cg_read_long(test_group, "memory.current");
-	expected_current = old_current + MB(8);
+	expected_current = old_current + length;
 	if (!values_close(expected_current, current, 5)) {
-		ksft_print_msg("memory usage should increase by around 8MB.\n");
+		ksft_print_msg("memory usage should increase by around 4 huge pages.\n");
 		ksft_print_msg(
 			"expected memory: %ld, actual memory: %ld\n",
 			expected_current, current);
@@ -147,7 +171,7 @@ static int hugetlb_test_program(const char *cgroup, void *arg)
 	}
 
 	/* unmap the whole range */
-	munmap(addr, LENGTH);
+	munmap(addr, length);
 	current = cg_read_long(test_group, "memory.current");
 	expected_current = old_current;
 	if (!values_close(expected_current, current, 5)) {
@@ -162,13 +186,15 @@ static int hugetlb_test_program(const char *cgroup, void *arg)
 	return ret;
 
 out_failed_munmap:
-	munmap(addr, LENGTH);
+	munmap(addr, length);
 	return ret;
 }
 
 static int test_hugetlb_memcg(char *root)
 {
 	int ret = KSFT_FAIL;
+	int num_pages = 20;
+	long hpage_size = get_hugepage_size();
 	char *test_group;
 
 	test_group = cg_name(root, "hugetlb_memcg_test");
@@ -177,7 +203,7 @@ static int test_hugetlb_memcg(char *root)
 		goto out;
 	}
 
-	if (cg_write(test_group, "memory.max", "100M")) {
+	if (cg_write_numeric(test_group, "memory.max", num_pages * hpage_size * 1024)) {
 		ksft_print_msg("fail to set cgroup memory limit.\n");
 		goto out;
 	}
@@ -200,6 +226,7 @@ int main(int argc, char **argv)
 {
 	char root[PATH_MAX];
 	int ret = EXIT_SUCCESS, has_memory_hugetlb_acc;
+	long val;
 
 	has_memory_hugetlb_acc = proc_mount_contains("memory_hugetlb_accounting");
 	if (has_memory_hugetlb_acc < 0)
@@ -208,12 +235,15 @@ int main(int argc, char **argv)
 		ksft_exit_skip("memory hugetlb accounting is disabled\n");
 
 	/* Unit is kB! */
-	if (get_hugepage_size() != 2048) {
-		ksft_print_msg("test_hugetlb_memcg requires 2MB hugepages\n");
+	val = get_hugepage_size();
+	if (val < 0) {
+		ksft_print_msg("Failed to read hugepage size\n");
 		ksft_test_result_skip("test_hugetlb_memcg\n");
 		return ret;
 	}
 
+	ksft_print_msg("Hugepage size: %ld kB\n", val);
+
 	if (cg_find_unified_root(root, sizeof(root), NULL))
 		ksft_exit_skip("cgroup v2 isn't mounted\n");
 
-- 
2.52.0