* [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels
@ 2026-09-07 2:00 Karl Mehltretter
2026-09-07 2:05 ` sashiko-bot
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Karl Mehltretter @ 2026-09-07 2:00 UTC (permalink / raw)
To: Sumit Semwal, Christian König
Cc: Karl Mehltretter, linux-media, dri-devel, linaro-mm-sig
Commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG
kernels") changed the default of DMABUF_DEBUG to "y if DEBUG", but no
Kconfig symbol DEBUG exists, so the option has had no default since.
Use DEBUG_KERNEL, the Kconfig symbol for a debug kernel.
Fixes: 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
This enables the dma-buf debug checks on every CONFIG_DEBUG_KERNEL
configuration, which is what 646013f513f3 set out to do. If that is too
broad today, the alternative is to restore the previous
"default y if DMA_API_DEBUG".
drivers/dma-buf/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
index 7efc0f0d0712..e4f078a326a4 100644
--- a/drivers/dma-buf/Kconfig
+++ b/drivers/dma-buf/Kconfig
@@ -43,7 +43,7 @@ config UDMABUF
config DMABUF_DEBUG
bool "DMA-BUF debug checks"
depends on DMA_SHARED_BUFFER
- default y if DEBUG
+ default y if DEBUG_KERNEL
help
This option enables additional checks for DMA-BUF importers and
exporters. Specifically it validates that importers do not peek at the
base-commit: 986c24e0fe44f844b44d365b71ce831947f50298
--
2.53.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels 2026-09-07 2:00 [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels Karl Mehltretter @ 2026-09-07 2:05 ` sashiko-bot 2026-09-11 10:03 ` Christian König 2026-09-28 19:28 ` Diederik de Haas 2 siblings, 0 replies; 6+ messages in thread From: sashiko-bot @ 2026-09-07 2:05 UTC (permalink / raw) To: Karl Mehltretter; +Cc: dri-devel, media-ci Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] Using DEBUG_KERNEL as a default trigger for DMABUF_DEBUG unintentionally enables performance-degrading debug checks on production kernels. -- commit 35e36d45a9285f1874efd2a5212588eb662aa118 Author: Karl Mehltretter <kmehltretter@gmail.com> dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels This commit replaces the non-existent DEBUG Kconfig symbol with DEBUG_KERNEL to ensure DMA-BUF debug checks are enabled on debug kernels. > diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig > index 7efc0f0d07126..e4f078a326a41 100644 > --- a/drivers/dma-buf/Kconfig > +++ b/drivers/dma-buf/Kconfig > @@ -43,7 +43,7 @@ config UDMABUF > config DMABUF_DEBUG > bool "DMA-BUF debug checks" > depends on DMA_SHARED_BUFFER > - default y if DEBUG > + default y if DEBUG_KERNEL [Severity: Medium] Will tying this default to DEBUG_KERNEL unintentionally cause a performance regression on production kernels? Because DEBUG_KERNEL is a top-level menu toggle enabled in virtually all production configurations and standard distributions, DMABUF_DEBUG will now be universally enabled by default. This introduces unnecessary dynamic heap allocations and scatterlist copying in dma_buf_map_attachment() via dma_buf_wrap_sg_table() during frequent map and unmap operations. Could this be tied to a more specific debugging option instead to prevent this regression on production systems? > help > This option enables additional checks for DMA-BUF importers and > exporters. Specifically it validates that importers do not peek at the -- Sashiko AI review · https://sashiko.dev/#/patchset/20260907020015.24719-1-kmehltretter@gmail.com?part=1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels 2026-09-07 2:00 [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels Karl Mehltretter 2026-09-07 2:05 ` sashiko-bot @ 2026-09-11 10:03 ` Christian König 2026-09-28 19:28 ` Diederik de Haas 2 siblings, 0 replies; 6+ messages in thread From: Christian König @ 2026-09-11 10:03 UTC (permalink / raw) To: Karl Mehltretter, Sumit Semwal; +Cc: linux-media, dri-devel, linaro-mm-sig On 9/7/26 04:00, Karl Mehltretter wrote: > Commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG > kernels") changed the default of DMABUF_DEBUG to "y if DEBUG", but no > Kconfig symbol DEBUG exists, so the option has had no default since. > > Use DEBUG_KERNEL, the Kconfig symbol for a debug kernel. > > Fixes: 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels") > Assisted-by: LLM > Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com> Reviewed and pushed to drm-misc-fixes. Thanks, Christian. > --- > This enables the dma-buf debug checks on every CONFIG_DEBUG_KERNEL > configuration, which is what 646013f513f3 set out to do. If that is too > broad today, the alternative is to restore the previous > "default y if DMA_API_DEBUG". > > drivers/dma-buf/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig > index 7efc0f0d0712..e4f078a326a4 100644 > --- a/drivers/dma-buf/Kconfig > +++ b/drivers/dma-buf/Kconfig > @@ -43,7 +43,7 @@ config UDMABUF > config DMABUF_DEBUG > bool "DMA-BUF debug checks" > depends on DMA_SHARED_BUFFER > - default y if DEBUG > + default y if DEBUG_KERNEL > help > This option enables additional checks for DMA-BUF importers and > exporters. Specifically it validates that importers do not peek at the > > base-commit: 986c24e0fe44f844b44d365b71ce831947f50298 > -- > 2.53.0 > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels 2026-09-07 2:00 [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels Karl Mehltretter @ 2026-09-28 19:28 ` Diederik de Haas 2026-09-11 10:03 ` Christian König 2026-09-28 19:28 ` Diederik de Haas 2 siblings, 0 replies; 6+ messages in thread From: Diederik de Haas @ 2026-09-28 19:28 UTC (permalink / raw) To: Karl Mehltretter, Sumit Semwal, Christian König Cc: linux-media, dri-devel, linaro-mm-sig, Sandy Huang, Heiko Stübner, Andy Yan, linux-rockchip, Detlev Casanova, Jonas Karlman On Mon Sep 7, 2026 at 4:00 AM CEST, Karl Mehltretter wrote: > Commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG > kernels") changed the default of DMABUF_DEBUG to "y if DEBUG", but no > Kconfig symbol DEBUG exists, so the option has had no default since. > > Use DEBUG_KERNEL, the Kconfig symbol for a debug kernel. I wondered why since 7.3-rc4 when playing videos I got a WHOLE lot of the following error messages, which weren't there with 7.3-rc3: [drm:rockchip_gem_iommu_map [rockchipdrm]] *ERROR* failed to map buffer: size=0 request_size=3956736 [drm:rockchip_gem_prime_import_sg_table [rockchipdrm]] *ERROR* failed to import sg table: -12 Both come from ``drivers/gpu/drm/rockchip/rockchip_drm_gem.c``. The value of request_size varies sometimes; I see ``request_size=8294400`` the most. When playing a video (with mpv with v4l2request functionality, but I think that doesn't matter), I see a whole bunch of these errors and then it stays 'silent', but I get another stream of them when I resize the window (ie I'm toggling between windowed and full-screen). It doesn't take long before dmesg only consists of these errors. The 'playing video' is likely important; when I just start sway I don't see those errors. It's only when I start a video that those pop up. My kernel (config) is based on Debian's and that has ``DEBUG_KERNEL=y`` at least since 2008 and due to this patch/commit, ``DMABUF_DEBUG`` got turned on. When I explicitly disable ``DMABUF_DEBUG``, I no longer see those errors. Whether that fixes or just hides a problem, I'll leave that for others to decide. > Fixes: 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels") > Assisted-by: LLM > Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com> > --- > This enables the dma-buf debug checks on every CONFIG_DEBUG_KERNEL > configuration, which is what 646013f513f3 set out to do. If that is too > broad today, the alternative is to restore the previous > "default y if DMA_API_DEBUG". My 0.02: That change landed in 7.0-rc1 albeit it didn't have the effect it intended to achieve. An -rc1 version seems like the right version to land such a change. I'm not in favor of this just popping up in 7.3-rc4 while -rc3 did NOT have that affect. With an -rc1 you'd expect major changes, but in this case I accidentally stumbled upon it while trying out something else. Cheers, Diederik > drivers/dma-buf/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig > index 7efc0f0d0712..e4f078a326a4 100644 > --- a/drivers/dma-buf/Kconfig > +++ b/drivers/dma-buf/Kconfig > @@ -43,7 +43,7 @@ config UDMABUF > config DMABUF_DEBUG > bool "DMA-BUF debug checks" > depends on DMA_SHARED_BUFFER > - default y if DEBUG > + default y if DEBUG_KERNEL > help > This option enables additional checks for DMA-BUF importers and > exporters. Specifically it validates that importers do not peek at the > > base-commit: 986c24e0fe44f844b44d365b71ce831947f50298 _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels @ 2026-09-28 19:28 ` Diederik de Haas 0 siblings, 0 replies; 6+ messages in thread From: Diederik de Haas @ 2026-09-28 19:28 UTC (permalink / raw) To: Karl Mehltretter, Sumit Semwal, Christian König Cc: linux-media, dri-devel, linaro-mm-sig, Sandy Huang, Heiko Stübner, Andy Yan, linux-rockchip, Detlev Casanova, Jonas Karlman On Mon Sep 7, 2026 at 4:00 AM CEST, Karl Mehltretter wrote: > Commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG > kernels") changed the default of DMABUF_DEBUG to "y if DEBUG", but no > Kconfig symbol DEBUG exists, so the option has had no default since. > > Use DEBUG_KERNEL, the Kconfig symbol for a debug kernel. I wondered why since 7.3-rc4 when playing videos I got a WHOLE lot of the following error messages, which weren't there with 7.3-rc3: [drm:rockchip_gem_iommu_map [rockchipdrm]] *ERROR* failed to map buffer: size=0 request_size=3956736 [drm:rockchip_gem_prime_import_sg_table [rockchipdrm]] *ERROR* failed to import sg table: -12 Both come from ``drivers/gpu/drm/rockchip/rockchip_drm_gem.c``. The value of request_size varies sometimes; I see ``request_size=8294400`` the most. When playing a video (with mpv with v4l2request functionality, but I think that doesn't matter), I see a whole bunch of these errors and then it stays 'silent', but I get another stream of them when I resize the window (ie I'm toggling between windowed and full-screen). It doesn't take long before dmesg only consists of these errors. The 'playing video' is likely important; when I just start sway I don't see those errors. It's only when I start a video that those pop up. My kernel (config) is based on Debian's and that has ``DEBUG_KERNEL=y`` at least since 2008 and due to this patch/commit, ``DMABUF_DEBUG`` got turned on. When I explicitly disable ``DMABUF_DEBUG``, I no longer see those errors. Whether that fixes or just hides a problem, I'll leave that for others to decide. > Fixes: 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels") > Assisted-by: LLM > Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com> > --- > This enables the dma-buf debug checks on every CONFIG_DEBUG_KERNEL > configuration, which is what 646013f513f3 set out to do. If that is too > broad today, the alternative is to restore the previous > "default y if DMA_API_DEBUG". My 0.02: That change landed in 7.0-rc1 albeit it didn't have the effect it intended to achieve. An -rc1 version seems like the right version to land such a change. I'm not in favor of this just popping up in 7.3-rc4 while -rc3 did NOT have that affect. With an -rc1 you'd expect major changes, but in this case I accidentally stumbled upon it while trying out something else. Cheers, Diederik > drivers/dma-buf/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig > index 7efc0f0d0712..e4f078a326a4 100644 > --- a/drivers/dma-buf/Kconfig > +++ b/drivers/dma-buf/Kconfig > @@ -43,7 +43,7 @@ config UDMABUF > config DMABUF_DEBUG > bool "DMA-BUF debug checks" > depends on DMA_SHARED_BUFFER > - default y if DEBUG > + default y if DEBUG_KERNEL > help > This option enables additional checks for DMA-BUF importers and > exporters. Specifically it validates that importers do not peek at the > > base-commit: 986c24e0fe44f844b44d365b71ce831947f50298 ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels 2026-09-28 19:28 ` Diederik de Haas (?) @ 2026-10-05 9:05 ` Diederik de Haas -1 siblings, 0 replies; 6+ messages in thread From: Diederik de Haas @ 2026-10-05 9:05 UTC (permalink / raw) To: linux-rockchip On Mon Sep 28, 2026 at 9:28 PM CEST, Diederik de Haas wrote: > On Mon Sep 7, 2026 at 4:00 AM CEST, Karl Mehltretter wrote: >> Commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG >> kernels") changed the default of DMABUF_DEBUG to "y if DEBUG", but no >> Kconfig symbol DEBUG exists, so the option has had no default since. >> >> Use DEBUG_KERNEL, the Kconfig symbol for a debug kernel. > > I wondered why since 7.3-rc4 when playing videos I got a WHOLE lot of the > following error messages, which weren't there with 7.3-rc3: > > [drm:rockchip_gem_iommu_map [rockchipdrm]] *ERROR* failed to map buffer: size=0 request_size=3956736 > [drm:rockchip_gem_prime_import_sg_table [rockchipdrm]] *ERROR* failed to import sg table: -12 > > Both come from ``drivers/gpu/drm/rockchip/rockchip_drm_gem.c``. > > ... > > When I explicitly disable ``DMABUF_DEBUG``, I no longer see those errors. > > Whether that fixes or just hides a problem, I'll leave that for others to > decide. It seems it hides the problem. Follow up with more context/links: https://lore.kernel.org/all/20261005064133.7305-1-kmehltretter@gmail.com/ _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-10-05 9:06 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-09-07 2:00 [PATCH] dma-buf: Make DMABUF_DEBUG default to y on DEBUG_KERNEL kernels Karl Mehltretter 2026-09-07 2:05 ` sashiko-bot 2026-09-11 10:03 ` Christian König 2026-09-28 19:28 ` Diederik de Haas 2026-09-28 19:28 ` Diederik de Haas 2026-10-05 9:05 ` Diederik de Haas
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