pkey01, futex_wake04 and memfd_create03 from ubuntu_ltp_syscalls failed with kvm kernel (Fail to open /proc/sys/vm/compact_memory for writing)

[Po-Hsu Lin]

This issue pops up after updating to the latest tip of LTP test suite (commit 776b57984 "rwtest: Remove df symlink check")

These failures are limited to kvm kernels and they're all failing with the same error message. memfd_create03 failure can only be found on newer kernels as it requires 4.14+.
Bisect shows this issue is caused by acf46111b5 "hugetlb: compacting memory to reduce fragmental pages" [1]

Test log for pkey01:
<<<test_start>>>
tag=pkey01 stime=1702291503
cmdline="pkey01"
contacts=""
analysis=exit
<<<test_output>>>
incrementing stop
tst_hugepage.c:50: TBROK: Failed to open FILE '/proc/sys/vm/compact_memory' for writing: ENOENT (2)
<<<execution_status>>>
initiation_status="ok"
duration=0 termination_type=exited termination_id=2 corefile=no
cutime=0 cstime=24
<<<test_end>>>

Test log for futex_wake04:
<<<test_start>>>
tag=futex_wake04 stime=1702291801
cmdline="futex_wake04"
contacts=""
analysis=exit
<<<test_output>>>
incrementing stop
tst_hugepage.c:50: TBROK: Failed to open FILE '/proc/sys/vm/compact_memory' for writing: ENOENT (2)
<<<execution_status>>>
initiation_status="ok"
duration=0 termination_type=exited termination_id=2 corefile=no
cutime=0 cstime=0
<<<test_end>>>

Test log for memfd_create03:
INFO: Test start time: Wed Dec 13 12:08:19 UTC 2023
COMMAND: /opt/ltp/bin/ltp-pan -q -e -S -a 869738 -n 869738 -f /tmp/ltp-fjHcQSE5qj/alltests -l /dev/null -C /dev/null -T /dev/null
LOG File: /dev/null
FAILED COMMAND File: /dev/null
TCONF COMMAND File: /dev/null
Running tests.......
tst_hugepage.c:50: TBROK: Failed to open FILE '/proc/sys/vm/compact_memory' for writing: ENOENT (2)
INFO: ltp-pan reported some tests FAIL
LTP Version: 20230929
INFO: Test end time: Wed Dec 13 12:08:19 UTC 2023

Before this change the pkey01 test will be skipped with:
<<<test_start>>>
tag=pkey01 stime=1702290779
cmdline="pkey01"
contacts=""
analysis=exit
<<<test_output>>>
incrementing stop
tst_hugepage.c:83: TINFO: 1 hugepage(s) reserved
tst_test.c:1560: TINFO: Timeout per run is 0h 00m 30s
pkey.h:27: TCONF: syscall(330) __NR_pkey_alloc not supported on your arch

Summary:
passed 0
failed 0
broken 0
skipped 1
warnings 0
<<<execution_status>>>
initiation_status="ok"
duration=0 termination_type=exited termination_id=32 corefile=no
cutime=0 cstime=0
<<<test_end>>>

The futex_wake04 test will pass with:
<<<test_start>>>
tag=futex_wake04 stime=1702292456
cmdline="futex_wake04"
contacts=""
analysis=exit
<<<test_output>>>
incrementing stop
tst_hugepage.c:83: TINFO: 1 hugepage(s) reserved
tst_test.c:1560: TINFO: Timeout per run is 0h 00m 30s
futex_wake04.c:52: TINFO: Testing variant: syscall with old kernel spec
futex_wake04.c:90: TINFO: Hugepagesize 2097152
futex_utils.h:59: TINFO: Thread 17485 not sleeping yet
futex_wake04.c:75: TPASS: Hi hydra, thread2 awake!

Summary:
passed 1
failed 0
broken 0
skipped 0
warnings 0
<<<execution_status>>>

The memfd_create03 test will pass with:
INFO: Test start time: Sat Oct 21 02:09:35 UTC 2023
COMMAND: /opt/ltp/bin/ltp-pan -q -e -S -a 868820 -n 868820 -f /tmp/ltp-a3y6bz0RdQ/alltests -l /dev/null -C /dev/null -T /dev/null
LOG File: /dev/null
FAILED COMMAND File: /dev/null
TCONF COMMAND File: /dev/null
Running tests.......
tst_hugepage.c:83: TINFO: 1 hugepage(s) reserved
tst_test.c:1558: TINFO: Timeout per run is 0h 00m 30s
memfd_create03.c:171: TINFO: --TESTING WRITE CALL IN HUGEPAGES--
memfd_create03.c:176: TINFO: memfd_create() succeeded
memfd_create03.c:70: TPASS: write(3, "LTP", 3) failed as expected

memfd_create03.c:171: TINFO: --TESTING PAGE SIZE OF CREATED FILE--
memfd_create03.c:176: TINFO: memfd_create() succeeded
memfd_create03.c:43: TINFO: mmap((nil), 2097152, 2, 2, 3, 0) succeeded
memfd_create03.c:92: TINFO: munmap(0x7fd6d3600000, 512kB) failed as expected
memfd_create03.c:92: TINFO: munmap(0x7fd6d3600000, 1024kB) failed as expected
memfd_create03.c:92: TINFO: munmap(0x7fd6d3600000, 1536kB) failed as expected
memfd_create03.c:111: TPASS: munmap() fails for page sizes less than 2048kB

memfd_create03.c:171: TINFO: --TESTING HUGEPAGE ALLOCATION LIMIT--
memfd_create03.c:176: TINFO: memfd_create() succeeded
memfd_create03.c:43: TINFO: mmap((nil), 2097152, 2, 2, 3, 0) succeeded
memfd_create03.c:131: TINFO: memfd_create() succeeded
memfd_create03.c:136: TPASS: mmap((nil), 2097152, 0, 2, 4, 0) failed as expected

Summary:
passed 3
failed 0
broken 0
skipped 0
warnings 0
INFO: ltp-pan reported all tests PASS
LTP Version: 20230516
INFO: Test end time: Sat Oct 21 02:09:35 UTC 2023

[1] https://github.com/linux-test-project/ltp/commit/acf46111b5cc0f4bfb2309a797f5b1a937e47ff8

[Po-Hsu Lin (cypressyew)]

memfd_create03 can be found failing with the same error message (this test requires 4.14+), I will update the bug title and description.