2022-12-15 17:36:51

by Arnd Bergmann

[permalink] [raw]
Subject: [PATCH] drm/tests: reduce drm_mm_test stack usage

From: Arnd Bergmann <[email protected]>

The check_reserve_boundaries function uses a lot of kernel stack,
and it gets inlined by clang, which makes __drm_test_mm_reserve
use even more of it, to the point of hitting the warning limit:

drivers/gpu/drm/tests/drm_mm_test.c:344:12: error: stack frame size (1048) exceeds limit (1024) in '__drm_test_mm_reserve' [-Werror,-Wframe-larger-than]

When building with gcc, this does not happen, but the structleak
plugin can similarly increase the stack usage and needs to be
disabled, as we do for all other kunit users.

Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/tests/Makefile | 2 ++
drivers/gpu/drm/tests/drm_mm_test.c | 2 +-
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tests/Makefile b/drivers/gpu/drm/tests/Makefile
index b29ef1085cad..f896ef85c2f2 100644
--- a/drivers/gpu/drm/tests/Makefile
+++ b/drivers/gpu/drm/tests/Makefile
@@ -12,3 +12,5 @@ obj-$(CONFIG_DRM_KUNIT_TEST) += \
drm_mm_test.o \
drm_plane_helper_test.o \
drm_rect_test.o
+
+CFLAGS_drm_mm_test.o := $(DISABLE_STRUCTLEAK_PLUGIN)
diff --git a/drivers/gpu/drm/tests/drm_mm_test.c b/drivers/gpu/drm/tests/drm_mm_test.c
index 89f12d3b4a21..90a5becc99b8 100644
--- a/drivers/gpu/drm/tests/drm_mm_test.c
+++ b/drivers/gpu/drm/tests/drm_mm_test.c
@@ -298,7 +298,7 @@ static bool expect_reserve_fail(struct kunit *test, struct drm_mm *mm, struct dr
return false;
}

-static bool check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
+static bool noinline_for_stack check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
unsigned int count,
u64 size)
{
--
2.35.1


2022-12-17 00:03:02

by Nathan Chancellor

[permalink] [raw]
Subject: Re: [PATCH] drm/tests: reduce drm_mm_test stack usage

On Thu, Dec 15, 2022 at 05:34:49PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> The check_reserve_boundaries function uses a lot of kernel stack,
> and it gets inlined by clang, which makes __drm_test_mm_reserve
> use even more of it, to the point of hitting the warning limit:
>
> drivers/gpu/drm/tests/drm_mm_test.c:344:12: error: stack frame size (1048) exceeds limit (1024) in '__drm_test_mm_reserve' [-Werror,-Wframe-larger-than]
>
> When building with gcc, this does not happen, but the structleak
> plugin can similarly increase the stack usage and needs to be
> disabled, as we do for all other kunit users.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Nathan Chancellor <[email protected]>

> ---
> drivers/gpu/drm/tests/Makefile | 2 ++
> drivers/gpu/drm/tests/drm_mm_test.c | 2 +-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/tests/Makefile b/drivers/gpu/drm/tests/Makefile
> index b29ef1085cad..f896ef85c2f2 100644
> --- a/drivers/gpu/drm/tests/Makefile
> +++ b/drivers/gpu/drm/tests/Makefile
> @@ -12,3 +12,5 @@ obj-$(CONFIG_DRM_KUNIT_TEST) += \
> drm_mm_test.o \
> drm_plane_helper_test.o \
> drm_rect_test.o
> +
> +CFLAGS_drm_mm_test.o := $(DISABLE_STRUCTLEAK_PLUGIN)
> diff --git a/drivers/gpu/drm/tests/drm_mm_test.c b/drivers/gpu/drm/tests/drm_mm_test.c
> index 89f12d3b4a21..90a5becc99b8 100644
> --- a/drivers/gpu/drm/tests/drm_mm_test.c
> +++ b/drivers/gpu/drm/tests/drm_mm_test.c
> @@ -298,7 +298,7 @@ static bool expect_reserve_fail(struct kunit *test, struct drm_mm *mm, struct dr
> return false;
> }
>
> -static bool check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
> +static bool noinline_for_stack check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
> unsigned int count,
> u64 size)
> {
> --
> 2.35.1
>

2022-12-20 19:31:56

by Maíra Canal

[permalink] [raw]
Subject: Re: [PATCH] drm/tests: reduce drm_mm_test stack usage

On 12/15/22 13:34, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> The check_reserve_boundaries function uses a lot of kernel stack,
> and it gets inlined by clang, which makes __drm_test_mm_reserve
> use even more of it, to the point of hitting the warning limit:
>
> drivers/gpu/drm/tests/drm_mm_test.c:344:12: error: stack frame size (1048) exceeds limit (1024) in '__drm_test_mm_reserve' [-Werror,-Wframe-larger-than]
>
> When building with gcc, this does not happen, but the structleak
> plugin can similarly increase the stack usage and needs to be
> disabled, as we do for all other kunit users.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Apart from the checkpatch problem on the function
check_reserve_boundaries(),

Reviewed-by: Maíra Canal <[email protected]>

Best Regards,
- Maíra Canal

> ---
> drivers/gpu/drm/tests/Makefile | 2 ++
> drivers/gpu/drm/tests/drm_mm_test.c | 2 +-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/tests/Makefile b/drivers/gpu/drm/tests/Makefile
> index b29ef1085cad..f896ef85c2f2 100644
> --- a/drivers/gpu/drm/tests/Makefile
> +++ b/drivers/gpu/drm/tests/Makefile
> @@ -12,3 +12,5 @@ obj-$(CONFIG_DRM_KUNIT_TEST) += \
> drm_mm_test.o \
> drm_plane_helper_test.o \
> drm_rect_test.o
> +
> +CFLAGS_drm_mm_test.o := $(DISABLE_STRUCTLEAK_PLUGIN)
> diff --git a/drivers/gpu/drm/tests/drm_mm_test.c b/drivers/gpu/drm/tests/drm_mm_test.c
> index 89f12d3b4a21..90a5becc99b8 100644
> --- a/drivers/gpu/drm/tests/drm_mm_test.c
> +++ b/drivers/gpu/drm/tests/drm_mm_test.c
> @@ -298,7 +298,7 @@ static bool expect_reserve_fail(struct kunit *test, struct drm_mm *mm, struct dr
> return false;
> }
>
> -static bool check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
> +static bool noinline_for_stack check_reserve_boundaries(struct kunit *test, struct drm_mm *mm,
> unsigned int count,
> u64 size)
> {

2022-12-23 23:01:55

by Maíra Canal

[permalink] [raw]
Subject: Re: [PATCH] drm/tests: reduce drm_mm_test stack usage

On 12/15/22 13:34, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> The check_reserve_boundaries function uses a lot of kernel stack,
> and it gets inlined by clang, which makes __drm_test_mm_reserve
> use even more of it, to the point of hitting the warning limit:
>
> drivers/gpu/drm/tests/drm_mm_test.c:344:12: error: stack frame size (1048) exceeds limit (1024) in '__drm_test_mm_reserve' [-Werror,-Wframe-larger-than]
>
> When building with gcc, this does not happen, but the structleak
> plugin can similarly increase the stack usage and needs to be
> disabled, as we do for all other kunit users.
>
> Signed-off-by: Arnd Bergmann <[email protected]>

Applied it to drm-misc-next-fixes with the small checkpatch fix.

Best Regards,
- Maíra Canal