Re: [Nouveau] [PATCH] mm/migrate.c: Remove MIGRATE_PFN_LOCKED
Am 2021-10-25 um 12:16 a.m. schrieb Alistair Popple:
> MIGRATE_PFN_LOCKED is used to indicate to migrate_vma_prepare() that a
> source page was already locked during migrate_vma_collect(). If it
> wasn't then the a second attempt is made to lock the page. However if
> the first attempt failed it's unlikely a second attempt will succeed,
> and the retry adds complexity. So clean this up by removing the retry
> and MIGRATE_PFN_LOCKED flag.
>
> Destination pages are also meant to have the MIGRATE_PFN_LOCKED flag
> set, but nothing actually checks that.
>
> Signed-off-by: Alistair Popple
It makes sense to me. Do you have any empirical data on how much more
likely migrations are going to fail with this change due to contested
page locks?
Either way, the patch is
Acked-by: Felix Kuehling
> ---
> Documentation/vm/hmm.rst | 2 +-
> arch/powerpc/kvm/book3s_hv_uvmem.c | 4 +-
> drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 2 -
> drivers/gpu/drm/nouveau/nouveau_dmem.c | 4 +-
> include/linux/migrate.h | 1 -
> lib/test_hmm.c | 5 +-
> mm/migrate.c | 145 +--
> 7 files changed, 35 insertions(+), 128 deletions(-)
>
> diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst
> index a14c2938e7af..f2a59ed82ed3 100644
> --- a/Documentation/vm/hmm.rst
> +++ b/Documentation/vm/hmm.rst
> @@ -360,7 +360,7 @@ between device driver specific code and shared common
> code:
> system memory page, locks the page with ``lock_page()``, and fills in the
> ``dst`` array entry with::
>
> - dst[i] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
> + dst[i] = migrate_pfn(page_to_pfn(dpage));
>
> Now that the driver knows that this page is being migrated, it can
> invalidate device private MMU mappings and copy device private memory
> diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c
> b/arch/powerpc/kvm/book3s_hv_uvmem.c
> index a7061ee3b157..28c436df9935 100644
> --- a/arch/powerpc/kvm/book3s_hv_uvmem.c
> +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
> @@ -560,7 +560,7 @@ static int __kvmppc_svm_page_out(struct vm_area_struct
> *vma,
> gpa, 0, page_shift);
>
> if (ret == U_SUCCESS)
> - *mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
> + *mig.dst = migrate_pfn(pfn);
> else {
> unlock_page(dpage);
> __free_page(dpage);
> @@ -774,7 +774,7 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma,
> }
> }
>
> - *mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
> + *mig.dst = migrate_pfn(page_to_pfn(dpage));
> migrate_vma_pages();
> out_finalize:
> migrate_vma_finalize();
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> index 4a16e3c257b9..41d9417f182b 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
> @@ -300,7 +300,6 @@ svm_migrate_copy_to_vram(struct amdgpu_device *adev,
> struct svm_range *prange,
> migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
> svm_migrate_get_vram_page(prange, migrate->dst[i]);
> migrate->dst[i] = migrate_pfn(migrate->dst[i]);
> - migrate->dst[i] |= MIGRATE_PFN_LOCKED;
> src[i] = dma_map_page(dev, spage, 0, PAGE_SIZE,
> DMA_TO_DEVICE);
> r = dma_mapping_error(dev, src[i]);
> @@ -580,7 +579,6 @@ svm_migrate_copy_to_ram(struct amdgpu_device *adev,
> struct svm_range *prange,
> dst[i] >> PAGE_SHIFT, page_to_pfn(dpage));
>
> migrate->dst[i] = migrate_pfn(page_to_pfn(dpage));
> - migrate->dst[i] |= MIGRATE_PFN_LOCKED;
> j++;
> }
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> index 92987daa5e17..3828aafd3ac4 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> @@ -166,7 +166,7 @@ static vm_fault_t nouveau_dmem_fault_copy_one(struct
> nouveau_drm *drm,
> goto error_dma_unmap;
> mutex_unlock(>mutex);
>
> - args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
> + args->dst[0] = migrate_pfn(page_to_pfn(dpage));
> return 0;
>
> error_dma_unmap:
> @@ -602,7 +602,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct
> nouveau_drm *drm,
> ((paddr >> PAGE_SHIFT) << NVIF_VMM_PFNMAP_V0_ADDR_SHIFT);
> if (src & MIGRATE_PFN_WRITE)
> *pfn |= NVIF_VMM_PFNMAP_V0_W;
> - return migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
> + return migrate_pfn(page_to_pfn(dpage));
>
> out_dma_unmap:
> dma_unmap_page(dev, *dma_addr,
Re: [Nouveau] [PATCH] mm/migrate.c: Remove MIGRATE_PFN_LOCKED
On 10/24/21 21:16, Alistair Popple wrote:
MIGRATE_PFN_LOCKED is used to indicate to migrate_vma_prepare() that a
source page was already locked during migrate_vma_collect(). If it
wasn't then the a second attempt is made to lock the page. However if
the first attempt failed it's unlikely a second attempt will succeed,
and the retry adds complexity. So clean this up by removing the retry
and MIGRATE_PFN_LOCKED flag.
Destination pages are also meant to have the MIGRATE_PFN_LOCKED flag
set, but nothing actually checks that.
Signed-off-by: Alistair Popple
You can add:
Reviewed-by: Ralph Campbell
---
Documentation/vm/hmm.rst | 2 +-
arch/powerpc/kvm/book3s_hv_uvmem.c | 4 +-
drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 2 -
drivers/gpu/drm/nouveau/nouveau_dmem.c | 4 +-
include/linux/migrate.h | 1 -
lib/test_hmm.c | 5 +-
mm/migrate.c | 145 +--
7 files changed, 35 insertions(+), 128 deletions(-)
diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst
index a14c2938e7af..f2a59ed82ed3 100644
--- a/Documentation/vm/hmm.rst
+++ b/Documentation/vm/hmm.rst
@@ -360,7 +360,7 @@ between device driver specific code and shared common code:
system memory page, locks the page with ``lock_page()``, and fills in the
``dst`` array entry with::
- dst[i] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ dst[i] = migrate_pfn(page_to_pfn(dpage));
Now that the driver knows that this page is being migrated, it can
invalidate device private MMU mappings and copy device private memory
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c
b/arch/powerpc/kvm/book3s_hv_uvmem.c
index a7061ee3b157..28c436df9935 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -560,7 +560,7 @@ static int __kvmppc_svm_page_out(struct vm_area_struct *vma,
gpa, 0, page_shift);
if (ret == U_SUCCESS)
- *mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
+ *mig.dst = migrate_pfn(pfn);
else {
unlock_page(dpage);
__free_page(dpage);
@@ -774,7 +774,7 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma,
}
}
- *mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ *mig.dst = migrate_pfn(page_to_pfn(dpage));
migrate_vma_pages();
out_finalize:
migrate_vma_finalize();
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 4a16e3c257b9..41d9417f182b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -300,7 +300,6 @@ svm_migrate_copy_to_vram(struct amdgpu_device *adev, struct
svm_range *prange,
migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
svm_migrate_get_vram_page(prange, migrate->dst[i]);
migrate->dst[i] = migrate_pfn(migrate->dst[i]);
- migrate->dst[i] |= MIGRATE_PFN_LOCKED;
src[i] = dma_map_page(dev, spage, 0, PAGE_SIZE,
DMA_TO_DEVICE);
r = dma_mapping_error(dev, src[i]);
@@ -580,7 +579,6 @@ svm_migrate_copy_to_ram(struct amdgpu_device *adev, struct
svm_range *prange,
dst[i] >> PAGE_SHIFT, page_to_pfn(dpage));
migrate->dst[i] = migrate_pfn(page_to_pfn(dpage));
- migrate->dst[i] |= MIGRATE_PFN_LOCKED;
j++;
}
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 92987daa5e17..3828aafd3ac4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -166,7 +166,7 @@ static vm_fault_t nouveau_dmem_fault_copy_one(struct
nouveau_drm *drm,
goto error_dma_unmap;
mutex_unlock(>mutex);
- args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ args->dst[0] = migrate_pfn(page_to_pfn(dpage));
return 0;
error_dma_unmap:
@@ -602,7 +602,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct
nouveau_drm *drm,
((paddr >> PAGE_SHIFT) << NVIF_VMM_PFNMAP_V0_ADDR_SHIFT);
if (src & MIGRATE_PFN_WRITE)
*pfn |= NVIF_VMM_PFNMAP_V0_W;
- return migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ return migrate_pfn(page_to_pfn(dpage));
out_dma_unmap:
dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index c8077e936691..479b861ae490 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -119,7 +119,6 @@ static inline int migrate_misplaced_page(struct page *page,
*/
#define MIGRATE_PFN_VALID
[Nouveau] [PATCH] mm/migrate.c: Remove MIGRATE_PFN_LOCKED
MIGRATE_PFN_LOCKED is used to indicate to migrate_vma_prepare() that a
source page was already locked during migrate_vma_collect(). If it
wasn't then the a second attempt is made to lock the page. However if
the first attempt failed it's unlikely a second attempt will succeed,
and the retry adds complexity. So clean this up by removing the retry
and MIGRATE_PFN_LOCKED flag.
Destination pages are also meant to have the MIGRATE_PFN_LOCKED flag
set, but nothing actually checks that.
Signed-off-by: Alistair Popple
---
Documentation/vm/hmm.rst | 2 +-
arch/powerpc/kvm/book3s_hv_uvmem.c | 4 +-
drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 2 -
drivers/gpu/drm/nouveau/nouveau_dmem.c | 4 +-
include/linux/migrate.h | 1 -
lib/test_hmm.c | 5 +-
mm/migrate.c | 145 +--
7 files changed, 35 insertions(+), 128 deletions(-)
diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst
index a14c2938e7af..f2a59ed82ed3 100644
--- a/Documentation/vm/hmm.rst
+++ b/Documentation/vm/hmm.rst
@@ -360,7 +360,7 @@ between device driver specific code and shared common code:
system memory page, locks the page with ``lock_page()``, and fills in the
``dst`` array entry with::
- dst[i] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ dst[i] = migrate_pfn(page_to_pfn(dpage));
Now that the driver knows that this page is being migrated, it can
invalidate device private MMU mappings and copy device private memory
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c
b/arch/powerpc/kvm/book3s_hv_uvmem.c
index a7061ee3b157..28c436df9935 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -560,7 +560,7 @@ static int __kvmppc_svm_page_out(struct vm_area_struct *vma,
gpa, 0, page_shift);
if (ret == U_SUCCESS)
- *mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
+ *mig.dst = migrate_pfn(pfn);
else {
unlock_page(dpage);
__free_page(dpage);
@@ -774,7 +774,7 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma,
}
}
- *mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ *mig.dst = migrate_pfn(page_to_pfn(dpage));
migrate_vma_pages();
out_finalize:
migrate_vma_finalize();
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 4a16e3c257b9..41d9417f182b 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -300,7 +300,6 @@ svm_migrate_copy_to_vram(struct amdgpu_device *adev, struct
svm_range *prange,
migrate->dst[i] = svm_migrate_addr_to_pfn(adev, dst[i]);
svm_migrate_get_vram_page(prange, migrate->dst[i]);
migrate->dst[i] = migrate_pfn(migrate->dst[i]);
- migrate->dst[i] |= MIGRATE_PFN_LOCKED;
src[i] = dma_map_page(dev, spage, 0, PAGE_SIZE,
DMA_TO_DEVICE);
r = dma_mapping_error(dev, src[i]);
@@ -580,7 +579,6 @@ svm_migrate_copy_to_ram(struct amdgpu_device *adev, struct
svm_range *prange,
dst[i] >> PAGE_SHIFT, page_to_pfn(dpage));
migrate->dst[i] = migrate_pfn(page_to_pfn(dpage));
- migrate->dst[i] |= MIGRATE_PFN_LOCKED;
j++;
}
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c
b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 92987daa5e17..3828aafd3ac4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -166,7 +166,7 @@ static vm_fault_t nouveau_dmem_fault_copy_one(struct
nouveau_drm *drm,
goto error_dma_unmap;
mutex_unlock(>mutex);
- args->dst[0] = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ args->dst[0] = migrate_pfn(page_to_pfn(dpage));
return 0;
error_dma_unmap:
@@ -602,7 +602,7 @@ static unsigned long nouveau_dmem_migrate_copy_one(struct
nouveau_drm *drm,
((paddr >> PAGE_SHIFT) << NVIF_VMM_PFNMAP_V0_ADDR_SHIFT);
if (src & MIGRATE_PFN_WRITE)
*pfn |= NVIF_VMM_PFNMAP_V0_W;
- return migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ return migrate_pfn(page_to_pfn(dpage));
out_dma_unmap:
dma_unmap_page(dev, *dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index c8077e936691..479b861ae490 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -119,7 +119,6 @@ static inline int migrate_misplaced_page(struct page *page,
*/
#define MIGRATE_PFN_VALID (1UL << 0)
#define MIGRATE_PFN_MIGRATE(1UL << 1)
-#define MIGRATE_PFN_LOCKED (1UL << 2)
