[PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

[PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

[David Hildenbrand]

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@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: David Hildenbrand <david@redhat.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

Re: [PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

[Mina Almasry]

On Wed, Aug 21, 2024 at 8:31 AM David Hildenbrand <david@redhat.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@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: Muchun Song <muchun.song@linux.dev>
> Cc: Mina Almasry <almasrymina@google.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

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.

Reviewed-by: Mina Almasry <almasrymina@google.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

This looks correct. I don't think I expected killall not to wait.

>      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");

This seems like a simple refactor to only delete when shmaddr is set,
looks fine to me.

>         }
>         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);
>

Setting shmaddr seems correct and an oversight. I don't see shmaddr
set anywhere in the current code.

>                 break;
>         default:
> --
> 2.46.0
>


-- 
Thanks,
Mina

Re: [PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

[David Hildenbrand]

On 21.08.24 17:59, Mina Almasry wrote:
> On Wed, Aug 21, 2024 at 8:31 AM David Hildenbrand <david@redhat.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@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Shuah Khan <shuah@kernel.org>
>> Cc: Muchun Song <muchun.song@linux.dev>
>> Cc: Mina Almasry <almasrymina@google.com>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
> 
> 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@google.com>

Thanks!

-- 
Cheers,

David / dhildenb

Re: [PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

[Mario Casquero]

This patch has been successfully tested. All hugetlb kernel selftests pass now.
# SUMMARY: PASS=12 SKIP=0 FAIL=0

Tested by: Mario Casquero <mcasquer@redhat.com>


On Wed, Aug 21, 2024 at 2:31 PM David Hildenbrand <david@redhat.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@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: Muchun Song <muchun.song@linux.dev>
> Cc: Mina Almasry <almasrymina@google.com>
> Signed-off-by: David Hildenbrand <david@redhat.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
>

Re: [PATCH v1] selftests/mm: fix charge_reserved_hugetlb.sh test

[Mario Casquero]

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

On Mon, Aug 26, 2024 at 4:16 PM Mario Casquero <mcasquer@redhat.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@redhat.com>
>
>
> On Wed, Aug 21, 2024 at 2:31 PM David Hildenbrand <david@redhat.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@redhat.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Shuah Khan <shuah@kernel.org>
> > Cc: Muchun Song <muchun.song@linux.dev>
> > Cc: Mina Almasry <almasrymina@google.com>
> > Signed-off-by: David Hildenbrand <david@redhat.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
> >