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selftests/mm: fix charge_reserved_hugetlb.sh test

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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: 29750f71a9 ("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>
This commit is contained in:
David Hildenbrand 2024-08-21 14:31:15 +02:00 committed by Andrew Morton
parent 7a87225ae2
commit c41a701d18
2 changed files with 14 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
tools/testing/selftests/mm/charge_reserved_hugetlb.sh
View file

@ -254,7 +254,7 @@ function cleanup_hugetlb_memory() {
local cgroup="$1"
if [[ "$(pgrep -f write_to_hugetlbfs)" != "" ]]; then
echo killing write_to_hugetlbfs
killall -2 write_to_hugetlbfs
killall -2 --wait write_to_hugetlbfs
wait_for_hugetlb_memory_to_get_depleted $cgroup
fi
set -e

23
tools/testing/selftests/mm/write_to_hugetlbfs.c
View file

@ -28,7 +28,7 @@ enum method {
/* Global variables. */
static const char *self;
static char *shmaddr;
static int *shmaddr;
static int shmid;
/*
@ -47,15 +47,17 @@ void sig_handler(int signo)
{
printf("Received %d.\n", signo);
if (signo == SIGINT) {
printf("Deleting the memory\n");
if (shmdt((const void *)shmaddr) != 0) {
perror("Detach failure");
shmctl(shmid, IPC_RMID, NULL);
exit(4);
}
if (shmaddr) {
printf("Deleting the memory\n");
if (shmdt((const void *)shmaddr) != 0) {
perror("Detach failure");
shmctl(shmid, IPC_RMID, NULL);
exit(4);
}
shmctl(shmid, IPC_RMID, NULL);
printf("Done deleting the memory\n");
shmctl(shmid, IPC_RMID, NULL);
printf("Done deleting the memory\n");
}
}
exit(2);
}
@ -211,7 +213,8 @@ int main(int argc, char **argv)
shmctl(shmid, IPC_RMID, NULL);
exit(2);
}
printf("shmaddr: %p\n", ptr);
shmaddr = ptr;
printf("shmaddr: %p\n", shmaddr);
break;
default: