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Currently, running the charge_reserved_hugetlb.sh selftest we can
sometimes observe something like:
$ ./charge_reserved_hugetlb.sh -cgroup-v2
...
write_result is 0
After write:
hugetlb_usage=0
reserved_usage=10485760
killing write_to_hugetlbfs
Received 2.
Deleting the memory
Detach failure: Invalid argument
umount: /mnt/huge: target is busy.
Both cases are issues in the test.
While the unmount error seems to be racy, it will make the test fail:
$ ./run_vmtests.sh -t hugetlb
...
# [FAIL]
not ok 10 charge_reserved_hugetlb.sh -cgroup-v2 # exit=32
The issue is that we are not waiting for the write_to_hugetlbfs process to
quit. So it might still have a hugetlbfs file open, about which umount is
not happy. Fix that by making "killall" wait for the process to quit.
The other error ("Detach failure: Invalid argument") does not seem to
result in a test error, but is misleading. Turns out write_to_hugetlbfs.c
unconditionally tries to cleanup using shmdt(), even when we only
mmap()'ed a hugetlb file. Even worse, shmaddr is never even set for the
SHM case. Fix that as well.
With this change it seems to work as expected.
Link: https://lkml.kernel.org/r/20240821123115.2068812-1-david@redhat.com
Fixes: 29750f71a9b4 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Mario Casquero <mcasquer@redhat.com>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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