The patch titled Subject: selftests/mm: compaction_test: support platform with huge mount of memory has been added to the -mm mm-hotfixes-unstable branch. Its filename is selftests-mm-compaction_test-support-platform-with-huge-mount-of-memory.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

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

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------------------------------------------------------ From: Feng Tang feng.tang@linux.alibaba.com Subject: selftests/mm: compaction_test: support platform with huge mount of memory Date: Wed, 23 Apr 2025 18:36:45 +0800

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: bd67d5c15cc19 ("Test compaction of mlocked memory") Signed-off-by: Feng Tang feng.tang@linux.alibaba.com Acked-by: Dev Jain dev.jain@arm.com Cc: 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/mm/compaction_test.c | 19 ++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)

--- a/tools/testing/selftests/mm/compaction_test.c~selftests-mm-compaction_test-support-platform-with-huge-mount-of-memory +++ a/tools/testing/selftests/mm/compaction_test.c @@ -90,6 +90,8 @@ int check_compaction(unsigned long mem_f 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_f 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; }

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Patches currently in -mm which might be from feng.tang@linux.alibaba.com are

selftests-mm-compaction_test-support-platform-with-huge-mount-of-memory.patch