diff mbox series

[11/29] selftests/mm: Drop test_uffdio_zeropage_eexist

Message ID 20230330160717.3107010-1-peterx@redhat.com
State New
Headers
Series selftests/mm: Split / Refactor userfault test |

Commit Message

Peter Xu March 30, 2023, 4:07 p.m. UTC 
  The idea was trying to flip this var in the alarm handler from time to time
to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the
zeropage test so probably only used once, meanwhile we passed
"retry==false" so it'll never got tested anyway.

Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage
is set (!hugetlb).

One more thing to do is doing UFFDIO_REGISTER for the alias buffer too,
because otherwise the test won't even pass!  We were just lucky that this
test never really got ran at all.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 tools/testing/selftests/mm/userfaultfd.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

Comments

Mike Kravetz April 1, 2023, 12:03 a.m. UTC | #1 
On 03/30/23 12:07, Peter Xu wrote:
> The idea was trying to flip this var in the alarm handler from time to time
> to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the
> zeropage test so probably only used once, meanwhile we passed
> "retry==false" so it'll never got tested anyway.
> 
> Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage
> is set (!hugetlb).
> 
> One more thing to do is doing UFFDIO_REGISTER for the alias buffer too,
> because otherwise the test won't even pass!  We were just lucky that this
> test never really got ran at all.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  tools/testing/selftests/mm/userfaultfd.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)

Thanks!  With only passing "retry==false", that code is indeed dead.  I had
to read the code again to understand area_dst_alias.  Thanks for taking this
on as the code is difficult to understand.

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
David Hildenbrand April 3, 2023, 7:56 a.m. UTC | #2 
On 30.03.23 18:07, Peter Xu wrote:
> The idea was trying to flip this var in the alarm handler from time to time
> to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the
> zeropage test so probably only used once, meanwhile we passed
> "retry==false" so it'll never got tested anyway.
> 
> Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage
> is set (!hugetlb).
> 
> One more thing to do is doing UFFDIO_REGISTER for the alias buffer too,
> because otherwise the test won't even pass!  We were just lucky that this
> test never really got ran at all.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---

Reviewed-by: David Hildenbrand <david@redhat.com>
Peter Xu April 3, 2023, 4:16 p.m. UTC | #3 
On Fri, Mar 31, 2023 at 05:03:17PM -0700, Mike Kravetz wrote:
> On 03/30/23 12:07, Peter Xu wrote:
> > The idea was trying to flip this var in the alarm handler from time to time
> > to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the
> > zeropage test so probably only used once, meanwhile we passed
> > "retry==false" so it'll never got tested anyway.
> > 
> > Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage
> > is set (!hugetlb).
> > 
> > One more thing to do is doing UFFDIO_REGISTER for the alias buffer too,
> > because otherwise the test won't even pass!  We were just lucky that this
> > test never really got ran at all.
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> >  tools/testing/selftests/mm/userfaultfd.c | 20 +++++++++++---------
> >  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> Thanks!  With only passing "retry==false", that code is indeed dead.  I had
> to read the code again to understand area_dst_alias.  Thanks for taking this
> on as the code is difficult to understand.

Yes it's very confusing.  I plan to move on the cleanup to remove all these
global variables at least in the unit tests, but I'll first see how this
one goes.

> 
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

Thanks,
Mike Rapoport April 7, 2023, 9:48 a.m. UTC | #4 
On Thu, Mar 30, 2023 at 12:07:17PM -0400, Peter Xu wrote:
> The idea was trying to flip this var in the alarm handler from time to time
> to test -EEXIST of UFFDIO_ZEROPAGE, but firstly it's only used in the
> zeropage test so probably only used once, meanwhile we passed
> "retry==false" so it'll never got tested anyway.
> 
> Drop both sides so we always test UFFDIO_ZEROPAGE retries if has_zeropage
> is set (!hugetlb).
> 
> One more thing to do is doing UFFDIO_REGISTER for the alias buffer too,
> because otherwise the test won't even pass!  We were just lucky that this
> test never really got ran at all.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>

> ---
>  tools/testing/selftests/mm/userfaultfd.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c
> index d724f1c78847..3487ec0bfcc8 100644
> --- a/tools/testing/selftests/mm/userfaultfd.c
> +++ b/tools/testing/selftests/mm/userfaultfd.c
> @@ -88,7 +88,6 @@ static bool test_dev_userfaultfd;
>  /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
>  #define ALARM_INTERVAL_SECS 10
>  static volatile bool test_uffdio_copy_eexist = true;
> -static volatile bool test_uffdio_zeropage_eexist = true;
>  /* Whether to test uffd write-protection */
>  static bool test_uffdio_wp = true;
>  /* Whether to test uffd minor faults */
> @@ -1114,7 +1113,7 @@ static void retry_uffdio_zeropage(int ufd,
>  	}
>  }
> 
> -static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
> +static int __uffdio_zeropage(int ufd, unsigned long offset)
>  {
>  	struct uffdio_zeropage uffdio_zeropage;
>  	int ret;
> @@ -1138,11 +1137,8 @@ static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
>  		if (res != page_size) {
>  			err("UFFDIO_ZEROPAGE unexpected size");
>  		} else {
> -			if (test_uffdio_zeropage_eexist && retry) {
> -				test_uffdio_zeropage_eexist = false;
> -				retry_uffdio_zeropage(ufd, &uffdio_zeropage,
> -						      offset);
> -			}
> +			retry_uffdio_zeropage(ufd, &uffdio_zeropage,
> +					      offset);
>  			return 1;
>  		}
>  	} else
> @@ -1153,7 +1149,7 @@ static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
> 
>  static int uffdio_zeropage(int ufd, unsigned long offset)
>  {
> -	return __uffdio_zeropage(ufd, offset, false);
> +	return __uffdio_zeropage(ufd, offset);
>  }
> 
>  /* exercise UFFDIO_ZEROPAGE */
> @@ -1177,6 +1173,13 @@ static int userfaultfd_zeropage_test(void)
>  	assert_expected_ioctls_present(
>  		uffdio_register.mode, uffdio_register.ioctls);
> 
> +	if (area_dst_alias) {
> +		/* Needed this to test zeropage-retry on shared memory */
> +		uffdio_register.range.start = (unsigned long) area_dst_alias;
> +		if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
> +			err("register failure");
> +	}
> +
>  	if (uffdio_zeropage(uffd, 0))
>  		if (my_bcmp(area_dst, zeropage, page_size))
>  			err("zeropage is not zero");
> @@ -1763,7 +1766,6 @@ static void sigalrm(int sig)
>  	if (sig != SIGALRM)
>  		abort();
>  	test_uffdio_copy_eexist = true;
> -	test_uffdio_zeropage_eexist = true;
>  	alarm(ALARM_INTERVAL_SECS);
>  }
> 
> -- 
> 2.39.1
>
diff mbox series

Patch

diff --git a/tools/testing/selftests/mm/userfaultfd.c b/tools/testing/selftests/mm/userfaultfd.c
index d724f1c78847..3487ec0bfcc8 100644
--- a/tools/testing/selftests/mm/userfaultfd.c
+++ b/tools/testing/selftests/mm/userfaultfd.c
@@ -88,7 +88,6 @@  static bool test_dev_userfaultfd;
 /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
 #define ALARM_INTERVAL_SECS 10
 static volatile bool test_uffdio_copy_eexist = true;
-static volatile bool test_uffdio_zeropage_eexist = true;
 /* Whether to test uffd write-protection */
 static bool test_uffdio_wp = true;
 /* Whether to test uffd minor faults */
@@ -1114,7 +1113,7 @@  static void retry_uffdio_zeropage(int ufd,
 	}
 }
 
-static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
+static int __uffdio_zeropage(int ufd, unsigned long offset)
 {
 	struct uffdio_zeropage uffdio_zeropage;
 	int ret;
@@ -1138,11 +1137,8 @@  static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
 		if (res != page_size) {
 			err("UFFDIO_ZEROPAGE unexpected size");
 		} else {
-			if (test_uffdio_zeropage_eexist && retry) {
-				test_uffdio_zeropage_eexist = false;
-				retry_uffdio_zeropage(ufd, &uffdio_zeropage,
-						      offset);
-			}
+			retry_uffdio_zeropage(ufd, &uffdio_zeropage,
+					      offset);
 			return 1;
 		}
 	} else
@@ -1153,7 +1149,7 @@  static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
 
 static int uffdio_zeropage(int ufd, unsigned long offset)
 {
-	return __uffdio_zeropage(ufd, offset, false);
+	return __uffdio_zeropage(ufd, offset);
 }
 
 /* exercise UFFDIO_ZEROPAGE */
@@ -1177,6 +1173,13 @@  static int userfaultfd_zeropage_test(void)
 	assert_expected_ioctls_present(
 		uffdio_register.mode, uffdio_register.ioctls);
 
+	if (area_dst_alias) {
+		/* Needed this to test zeropage-retry on shared memory */
+		uffdio_register.range.start = (unsigned long) area_dst_alias;
+		if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
+			err("register failure");
+	}
+
 	if (uffdio_zeropage(uffd, 0))
 		if (my_bcmp(area_dst, zeropage, page_size))
 			err("zeropage is not zero");
@@ -1763,7 +1766,6 @@  static void sigalrm(int sig)
 	if (sig != SIGALRM)
 		abort();
 	test_uffdio_copy_eexist = true;
-	test_uffdio_zeropage_eexist = true;
 	alarm(ALARM_INTERVAL_SECS);
 }