On 21.08.24 17:59, Mina Almasry wrote:
On Wed, Aug 21, 2024 at 8:31 AM David Hildenbrand <david@xxxxxxxxxx> wrote: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. Fixes: 29750f71a9b4 ("hugetlb_cgroup: add hugetlb_cgroup reservation tests") Reported-by: Mario Casquero <mcasquer@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: Muchun Song <muchun.song@xxxxxxxxx> Cc: Mina Almasry <almasrymina@xxxxxxxxxx> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>Initially I thought it could be nice to split fixes for the 2 issues in separate patches in case one of them ends up needing a revert or something, but probably not worth a respin. Fixes look good to me.
I was debating with myself as well if it should be separated, but decided to go the simple route of a single patch :)
Reviewed-by: Mina Almasry <almasrymina@xxxxxxxxxx>
Thanks! -- Cheers, David / dhildenb
