mm: handle multiple owners of device private pages in migrate_vma

Add a new src_owner field to struct migrate_vma.  If the field is set,
only device private pages with page->pgmap->owner equal to that field are
migrated.  If the field is not set only "normal" pages are migrated.

Fixes: df6ad69838fc ("mm/device-public-memory: device memory cache coherent with CPU")
Link: https://lore.kernel.org/r/20200316193216.920734-3-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Tested-by: Bharata B Rao <bharata@linux.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 67fefb0..f44f6b2 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -563,6 +563,7 @@ kvmppc_svm_page_out(struct vm_area_struct *vma, unsigned long start,
        mig.end = end;
        mig.src = &src_pfn;
        mig.dst = &dst_pfn;
+       mig.src_owner = &kvmppc_uvmem_pgmap;
 
        mutex_lock(&kvm->arch.uvmem_lock);
        /* The requested page is already paged-out, nothing to do */

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index a468227..0e36345 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -176,6 +176,7 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf)
                .end            = vmf->address + PAGE_SIZE,
                .src            = &src,
                .dst            = &dst,
+               .src_owner      = drm->dev,
        };
 
        /*

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 7212006..3e546cb 100644 (file)
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -196,6 +196,14 @@ struct migrate_vma {
        unsigned long           npages;
        unsigned long           start;
        unsigned long           end;
+
+       /*
+        * Set to the owner value also stored in page->pgmap->owner for
+        * migrating out of device private memory.  If set only device
+        * private pages with this owner are migrated.  If not set
+        * device private pages are not migrated at all.
+        */
+       void                    *src_owner;
 };
 
 int migrate_vma_setup(struct migrate_vma *args);

diff --git a/mm/migrate.c b/mm/migrate.c
index b109287..7605d2c 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2241,7 +2241,7 @@ again:
        arch_enter_lazy_mmu_mode();
 
        for (; addr < end; addr += PAGE_SIZE, ptep++) {
-               unsigned long mpfn, pfn;
+               unsigned long mpfn = 0, pfn;
                struct page *page;
                swp_entry_t entry;
                pte_t pte;
@@ -2255,8 +2255,6 @@ again:
                }
 
                if (!pte_present(pte)) {
-                       mpfn = 0;
-
                        /*
                         * Only care about unaddressable device page special
                         * page table entry. Other special swap entries are not
@@ -2267,11 +2265,16 @@ again:
                                goto next;
 
                        page = device_private_entry_to_page(entry);
+                       if (page->pgmap->owner != migrate->src_owner)
+                               goto next;
+
                        mpfn = migrate_pfn(page_to_pfn(page)) |
                                        MIGRATE_PFN_MIGRATE;
                        if (is_write_device_private_entry(entry))
                                mpfn |= MIGRATE_PFN_WRITE;
                } else {
+                       if (migrate->src_owner)
+                               goto next;
                        pfn = pte_pfn(pte);
                        if (is_zero_pfn(pfn)) {
                                mpfn = MIGRATE_PFN_MIGRATE;