linux-kernel - Re: [PATCH v1] selftests/mm: fix charge_reserved

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Message-ID: <CAMXpfWuMZJqDndoNX7no4vJm9d0RwkV=OQ3XqQHqkj1YfvsmVw@mail.gmail.com>
Date: Mon, 26 Aug 2024 16:18:11 +0200
From: Mario Casquero <mcasquer@...hat.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	linux-kselftest@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, 
	Shuah Khan <shuah@...nel.org>, Muchun Song <muchun.song@...ux.dev>, 
	Mina Almasry <almasrymina@...gle.com>
Subject: Re: [PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

Missing the hyphen :)
Tested-by: Mario Casquero <mcasquer@...hat.com>

On Mon, Aug 26, 2024 at 4:16 PM Mario Casquero <mcasquer@...hat.com> wrote:
>
> This patch has been successfully tested. All hugetlb kernel selftests pass now.
> # SUMMARY: PASS=12 SKIP=0 FAIL=0
>
> Tested by: Mario Casquero <mcasquer@...hat.com>
>
>
> On Wed, Aug 21, 2024 at 2:31 PM David Hildenbrand <david@...hat.com> 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@...hat.com>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: Shuah Khan <shuah@...nel.org>
> > Cc: Muchun Song <muchun.song@...ux.dev>
> > Cc: Mina Almasry <almasrymina@...gle.com>
> > Signed-off-by: David Hildenbrand <david@...hat.com>
> > ---
> >  .../selftests/mm/charge_reserved_hugetlb.sh   |  2 +-
> >  .../testing/selftests/mm/write_to_hugetlbfs.c | 21 +++++++++++--------
> >  2 files changed, 13 insertions(+), 10 deletions(-)
> >
> > diff --git a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
> > index d680c00d2853a..67df7b47087f0 100755
> > --- a/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
> > +++ b/tools/testing/selftests/mm/charge_reserved_hugetlb.sh
> > @@ -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
> > diff --git a/tools/testing/selftests/mm/write_to_hugetlbfs.c b/tools/testing/selftests/mm/write_to_hugetlbfs.c
> > index 6a2caba19ee1d..1289d311efd70 100644
> > --- a/tools/testing/selftests/mm/write_to_hugetlbfs.c
> > +++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c
> > @@ -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");
> > +               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);
> > -                       exit(4);
> > +                       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:
> > --
> > 2.46.0
> >