mmap04 from ubuntu_ltp_syscalls failed with T-lts

[Po-Hsu Lin]

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

I think the failure is because of the API and test case change in https://github.com/linux-test-project/ltp/commit/dd7b485850d28fd5a0b54662f8f7958e677f6a0c

It's only failing with T-lts (4.4.0-248.282~14.04.1), passed with Xenial and newer kernels.

Test log:
INFO: Test start time: Wed Dec 6 08:32:32 UTC 2023
COMMAND: /opt/ltp/bin/ltp-pan -q -e -S -a 29128 -n 29128 -f /tmp/ltp-8MxzruVH2X/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_test.c:1690: TINFO: LTP version: 20230929
tst_test.c:1576: TINFO: Timeout per run is 0h 00m 30s
mmap04.c:58: TPASS: mapping permissions in /proc matched: ---p
mmap04.c:58: TPASS: mapping permissions in /proc matched: ---s
mmap04.c:58: TPASS: mapping permissions in /proc matched: r--p
mmap04.c:58: TPASS: mapping permissions in /proc matched: r--s
mmap04.c:58: TPASS: mapping permissions in /proc matched: -w-p
mmap04.c:58: TPASS: mapping permissions in /proc matched: -w-s
mmap04.c:55: TBROK: Expected 1 conversions got 0 FILE '/proc/self/maps'

Summary:
passed 6
failed 0
broken 1
skipped 0
warnings 0
INFO: ltp-pan reported some tests FAIL
LTP Version: 20230929
INFO: Test end time: Wed Dec 6 08:32:32 UTC 2023

[Po-Hsu Lin (cypressyew)]

This issue can be fixed by this commit upstream:
commit 6c4bf3a75f4ba17503bc2d8ba91a7514fdae995e
Author: Avinesh Kumar <email address hidden>
Date: Wed Jan 24 14:26:02 2024 +0100

    mmap04.c: Avoid vma merging

    We hit a scenario where new mapping was merged with existing mapping of
    same permission and the return address from the mmap was hidden in the
    merged mapping in /proc/self/maps, causing the test to fail.
    To avoid this, we first create a 2-page mapping with the different
    permissions, and then remap the 2nd page with the perms being tested.

    Link: https://<email address hidden>/
    Reported-by: Martin Doucha <email address hidden>
    Reviewed-by: Martin Doucha <email address hidden>
    Reviewed-by: Petr Vorel <email address hidden>
    Signed-off-by: Avinesh Kumar <email address hidden>