Commit ab09243a authored by Alistair Popple's avatar Alistair Popple Committed by Linus Torvalds
Browse files

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.

Link: https://lkml.kernel.org/r/20211025041608.289017-1-apopple@nvidia.com


Signed-off-by: default avatarAlistair Popple <apopple@nvidia.com>
Reviewed-by: default avatarRalph Campbell <rcampbell@nvidia.com>
Acked-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0ef02462

Documentation/vm/hmm.rst

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kvm/book3s_hv_uvmem.c

+2 −2
Original line number Diff line number Diff line
@@ -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(&mig);

out_finalize:

	migrate_vma_finalize(&mig);

drivers/gpu/drm/amd/amdkfd/kfd_migrate.c

+0 −2
Original line number Diff line number Diff line
@@ -317,7 +317,6 @@ 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]);
@@ -610,7 +609,6 @@ 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++;

	}

drivers/gpu/drm/nouveau/nouveau_dmem.c

+2 −2
Original line number Diff line number Diff line
@@ -166,7 +166,7 @@ static vm_fault_t nouveau_dmem_fault_copy_one(struct nouveau_drm *drm, 
		goto error_dma_unmap;

	mutex_unlock(&svmm->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);

include/linux/migrate.h

+0 −1
Original line number Diff line number Diff line
@@ -110,7 +110,6 @@ 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)

#define MIGRATE_PFN_WRITE	(1UL << 3)

#define MIGRATE_PFN_SHIFT	6