diff mbox series

[hmm,v2,1/5] mm/hmm: make CONFIG_DEVICE_PRIVATE into a select

Message ID 1-v2-b4e84f444c7d+24f57-hmm_no_flags_jgg@mellanox.com (mailing list archive)
State New, archived
Headers show
Series Adjust hmm_range_fault() API | expand

Commit Message

Jason Gunthorpe May 1, 2020, 6:20 p.m. UTC 
From: Jason Gunthorpe <jgg@mellanox.com>

There is no reason for a user to select this or not directly - it should
be selected by drivers that are going to use the feature, similar to how
CONFIG_HMM_MIRROR works.

Currently all drivers provide a feature kconfig that will disable use of
DEVICE_PRIVATE in that driver, allowing users to avoid enabling this if
they don't want the overhead.

Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
---
 arch/powerpc/Kconfig            | 2 +-
 drivers/gpu/drm/nouveau/Kconfig | 2 +-
 mm/Kconfig                      | 7 +------
 3 files changed, 3 insertions(+), 8 deletions(-)

Comments

Andrew Morton May 10, 2020, 12:16 a.m. UTC | #1 
On Fri,  1 May 2020 15:20:44 -0300 Jason Gunthorpe <jgg@ziepe.ca> wrote:

> From: Jason Gunthorpe <jgg@mellanox.com>
> 
> There is no reason for a user to select this or not directly - it should
> be selected by drivers that are going to use the feature, similar to how
> CONFIG_HMM_MIRROR works.
> 
> Currently all drivers provide a feature kconfig that will disable use of
> DEVICE_PRIVATE in that driver, allowing users to avoid enabling this if
> they don't want the overhead.
> 

I'm not too sure what's going on here, but i386 allmodconfig broke.

kernel/resource.c: In function '__request_free_mem_region':
kernel/resource.c:1653:28: error: 'PA_SECTION_SHIFT' undeclared (first use in this function); did you mean 'SECTIONS_PGSHIFT'?
  size = ALIGN(size, 1UL << PA_SECTION_SHIFT);

because in current mainline, allmodconfig produces
CONFIG_DEVICE_PRIVATE=n but in current linux-next, allmodconfig
produces CONFIG_DEVICE_PRIVATE=y.  But CONFIG_SPARSEMEM=n so the build
breaks.

Bisection fingers this commit, but reverting it doesn't seem to fix
things.  Could you take a look please?

I'm seeing this from menuconfig:

WARNING: unmet direct dependencies detected for DEVICE_PRIVATE
  Depends on [n]: ZONE_DEVICE [=n]
  Selected by [m]:
  - DRM_NOUVEAU_SVM [=y] && HAS_IOMEM [=y] && DRM_NOUVEAU [=m] && MMU [=y] && STAGING [=y]
  - TEST_HMM [=m] && RUNTIME_TESTING_MENU [=y] && TRANSPARENT_HUGEPAGE [=y]

`select' rather sucks this way - easy to break dependencies.  Quite a
number of years ago the Kconfig gurus were saying "avoid", but I don't
recall the details.
Jason Gunthorpe May 11, 2020, 1:49 p.m. UTC | #2 
On Sat, May 09, 2020 at 05:16:12PM -0700, Andrew Morton wrote:
> On Fri,  1 May 2020 15:20:44 -0300 Jason Gunthorpe <jgg@ziepe.ca> wrote:
> 
> > From: Jason Gunthorpe <jgg@mellanox.com>
> > 
> > There is no reason for a user to select this or not directly - it should
> > be selected by drivers that are going to use the feature, similar to how
> > CONFIG_HMM_MIRROR works.
> > 
> > Currently all drivers provide a feature kconfig that will disable use of
> > DEVICE_PRIVATE in that driver, allowing users to avoid enabling this if
> > they don't want the overhead.
> > 
> 
> I'm not too sure what's going on here, but i386 allmodconfig broke.
> 
> kernel/resource.c: In function '__request_free_mem_region':
> kernel/resource.c:1653:28: error: 'PA_SECTION_SHIFT' undeclared (first use in this function); did you mean 'SECTIONS_PGSHIFT'?
>   size = ALIGN(size, 1UL << PA_SECTION_SHIFT);
> 
> because in current mainline, allmodconfig produces
> CONFIG_DEVICE_PRIVATE=n but in current linux-next, allmodconfig
> produces CONFIG_DEVICE_PRIVATE=y.  But CONFIG_SPARSEMEM=n so the build
> breaks.

I think Arnd identified this, let us just revet the patch that caused
it.

> Bisection fingers this commit, but reverting it doesn't seem to fix
> things.  Could you take a look please?

There is a latter patch adding a 'select DEVICE_PRIVATE' so reverting
this needs to swap that to 'depends on'.

I've done both and updated git

Regards,
Jason
diff mbox series

Patch

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 924c541a926008..8de52aefdc74cc 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -455,7 +455,7 @@  config PPC_TRANSACTIONAL_MEM
 config PPC_UV
 	bool "Ultravisor support"
 	depends on KVM_BOOK3S_HV_POSSIBLE
-	depends on DEVICE_PRIVATE
+	select DEVICE_PRIVATE
 	default n
 	help
 	  This option paravirtualizes the kernel to run in POWER platforms that
diff --git a/drivers/gpu/drm/nouveau/Kconfig b/drivers/gpu/drm/nouveau/Kconfig
index d6e4ae1ef7053a..af5793f3e7c2cf 100644
--- a/drivers/gpu/drm/nouveau/Kconfig
+++ b/drivers/gpu/drm/nouveau/Kconfig
@@ -86,10 +86,10 @@  config DRM_NOUVEAU_BACKLIGHT
 
 config DRM_NOUVEAU_SVM
 	bool "(EXPERIMENTAL) Enable SVM (Shared Virtual Memory) support"
-	depends on DEVICE_PRIVATE
 	depends on DRM_NOUVEAU
 	depends on MMU
 	depends on STAGING
+	select DEVICE_PRIVATE
 	select HMM_MIRROR
 	select MMU_NOTIFIER
 	default n
diff --git a/mm/Kconfig b/mm/Kconfig
index c1acc34c1c358c..7ca36bf5f5058e 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -805,15 +805,10 @@  config HMM_MIRROR
 	depends on MMU
 
 config DEVICE_PRIVATE
-	bool "Unaddressable device memory (GPU memory, ...)"
+	bool
 	depends on ZONE_DEVICE
 	select DEV_PAGEMAP_OPS
 
-	help
-	  Allows creation of struct pages to represent unaddressable device
-	  memory; i.e., memory that is only accessible from the device (or
-	  group of devices). You likely also want to select HMM_MIRROR.
-
 config FRAME_VECTOR
 	bool