5.15-stable review patch. If anyone has any objections, please let me know.
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From: Feng Tang feng.tang@linux.alibaba.com
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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/testing/selftests/vm/compaction_test.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
--- 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_f 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_f
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; }