FAILED: patch "[PATCH] selftests/mm: compaction_test: support platform with huge" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] selftests/mm: compaction_test: support platform with huge" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x ab00ddd802f80e31fc9639c652d736fe3913feae
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025051244-backwater-computer-184f@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ab00ddd802f80e31fc9639c652d736fe3913feae Mon Sep 17 00:00:00 2001
From: Feng Tang <feng.tang@linux.alibaba.com>
Date: Wed, 23 Apr 2025 18:36:45 +0800
Subject: [PATCH] selftests/mm: compaction_test: support platform with huge
 mount of memory

When running mm selftest to verify mm patches, 'compaction_test' case
failed on an x86 server with 1TB memory.  And the root cause is that it
has too much free memory than what the test supports.

The test case tries to allocate 100000 huge pages, which is about 200 GB
for that x86 server, and when it succeeds, it expects it's large than 1/3
of 80% of the free memory in system.  This logic only works for platform
with 750 GB ( 200 / (1/3) / 80% ) or less free memory, and may raise false
alarm for others.

Fix it by changing the fixed page number to self-adjustable number
according to the real number of free memory.

Link: https://lkml.kernel.org/r/20250423103645.2758-1-feng.tang@linux.alibaba.com
Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory")
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Acked-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@inux.alibaba.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Sri Jayaramappa <sjayaram@akamai.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c
index 2c3a0eb6b22d..9bc4591c7b16 100644
--- a/tools/testing/selftests/mm/compaction_test.c
+++ b/tools/testing/selftests/mm/compaction_test.c
@@ -90,6 +90,8 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
 	int compaction_index = 0;
 	char nr_hugepages[20] = {0};
 	char init_nr_hugepages[24] = {0};
+	char target_nr_hugepages[24] = {0};
+	int slen;
 
 	snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
 		 "%lu", initial_nr_hugepages);
@@ -106,11 +108,18 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
 		goto out;
 	}
 
-	/* Request a large number of huge pages. The Kernel will allocate
-	   as much as it can */
-	if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
-		ksft_print_msg("Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n",
-			       strerror(errno));
+	/*
+	 * Request huge pages for about half of the free memory. The Kernel
+	 * will allocate as much as it can, and we expect it will get at least 1/3
+	 */
+	nr_hugepages_ul = mem_free / hugepage_size / 2;
+	snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
+		 "%lu", nr_hugepages_ul);
+
+	slen = strlen(target_nr_hugepages);
+	if (write(fd, target_nr_hugepages, slen) != slen) {
+		ksft_print_msg("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
+			       nr_hugepages_ul, strerror(errno));
 		goto close_fd;
 	}
 

[PATCH 5.15.y] selftests/mm: compaction_test: support platform with huge mount of memory

[Feng Tang]

commit ab00ddd802f80e31fc9639c652d736fe3913feae upstream.

When running mm selftest to verify mm patches, 'compaction_test' case
failed on an x86 server with 1TB memory.  And the root cause is that it
has too much free memory than what the test supports.

The test case tries to allocate 100000 huge pages, which is about 200 GB
for that x86 server, and when it succeeds, it expects it's large than 1/3
of 80% of the free memory in system.  This logic only works for platform
with 750 GB ( 200 / (1/3) / 80% ) or less free memory, and may raise false
alarm for others.

Fix it by changing the fixed page number to self-adjustable number
according to the real number of free memory.

Link: https://lkml.kernel.org/r/20250423103645.2758-1-feng.tang@linux.alibaba.com
Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory")
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Acked-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Sri Jayaramappa <sjayaram@akamai.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 tools/testing/selftests/vm/compaction_test.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/vm/compaction_test.c b/tools/testing/selftests/vm/compaction_test.c
index 7c260060a1a6..00ebd9d508ff 100644
--- a/tools/testing/selftests/vm/compaction_test.c
+++ b/tools/testing/selftests/vm/compaction_test.c
@@ -89,6 +89,8 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size)
 	int compaction_index = 0;
 	char initial_nr_hugepages[20] = {0};
 	char nr_hugepages[20] = {0};
+	char target_nr_hugepages[24] = {0};
+	int slen;
 
 	/* We want to test with 80% of available memory. Else, OOM killer comes
 	   in to play */
@@ -118,11 +120,18 @@ int check_compaction(unsigned long mem_free, unsigned long hugepage_size)
 
 	lseek(fd, 0, SEEK_SET);
 
-	/* Request a large number of huge pages. The Kernel will allocate
-	   as much as it can */
-	if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
-		ksft_test_result_fail("Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n",
-				      strerror(errno));
+	/*
+	 * Request huge pages for about half of the free memory. The Kernel
+	 * will allocate as much as it can, and we expect it will get at least 1/3
+	 */
+	nr_hugepages_ul = mem_free / hugepage_size / 2;
+	snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
+		 "%lu", nr_hugepages_ul);
+
+	slen = strlen(target_nr_hugepages);
+	if (write(fd, target_nr_hugepages, slen) != slen) {
+		ksft_test_result_fail("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
+			       nr_hugepages_ul, strerror(errno));
 		goto close_fd;
 	}
 
-- 
2.39.5 (Apple Git-154)

Re: [PATCH 5.15.y] selftests/mm: compaction_test: support platform with huge mount of memory

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: ab00ddd802f80e31fc9639c652d736fe3913feae

Status in newer kernel trees:
6.14.y | Present (different SHA1: cc09dec6cce3)
6.12.y | Present (different SHA1: 72669f82feb1)
6.6.y | Not found
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  ab00ddd802f80 < -:  ------------- selftests/mm: compaction_test: support platform with huge mount of memory
-:  ------------- > 1:  4281d5a25f233 selftests/mm: compaction_test: support platform with huge mount of memory
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |