mm: simplify ZONE_DEVICE page private data

Remove the clumsy hmm_devmem_page_{get,set}_drvdata helpers, and
instead just access the page directly.  Also make the page data
a void pointer, and thus much easier to use.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

4 files changed, 12 insertions, 48 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 0fb7a44b8bc4..42c026010938 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -104,11 +104,8 @@ struct nouveau_migrate {
 
 static void nouveau_dmem_page_free(struct page *page)
 {
-        struct nouveau_dmem_chunk *chunk;
-        unsigned long idx;
-
-        chunk = (void *)hmm_devmem_page_get_drvdata(page);
-        idx = page_to_pfn(page) - chunk->pfn_first;
+        struct nouveau_dmem_chunk *chunk = page->zone_device_data;
+        unsigned long idx = page_to_pfn(page) - chunk->pfn_first;
 
         /*
          * FIXME:
@@ -200,7 +197,7 @@ nouveau_dmem_fault_alloc_and_copy(struct vm_area_struct *vma,
 
                 dst_addr = fault->dma[fault->npages++];
 
-                chunk = (void *)hmm_devmem_page_get_drvdata(spage);
+                chunk = spage->zone_device_data;
                 src_addr = page_to_pfn(spage) - chunk->pfn_first;
                 src_addr = (src_addr << PAGE_SHIFT) + chunk->bo->bo.offset;
 
@@ -633,9 +630,8 @@ nouveau_dmem_init(struct nouveau_drm *drm)
                 list_add_tail(&chunk->list, &drm->dmem->chunk_empty);
 
                 page = pfn_to_page(chunk->pfn_first);
-                for (j = 0; j < DMEM_CHUNK_NPAGES; ++j, ++page) {
-                        hmm_devmem_page_set_drvdata(page, (long)chunk);
-                }
+                for (j = 0; j < DMEM_CHUNK_NPAGES; ++j, ++page)
+                        page->zone_device_data = chunk;
         }
 
         NV_INFO(drm, "DMEM: registered %ldMB of device memory\n", size >> 20);
@@ -698,7 +694,7 @@ nouveau_dmem_migrate_alloc_and_copy(struct vm_area_struct *vma,
                 if (!dpage || dst_pfns[i] == MIGRATE_PFN_ERROR)
                         continue;
 
-                chunk = (void *)hmm_devmem_page_get_drvdata(dpage);
+                chunk = dpage->zone_device_data;
                 dst_addr = page_to_pfn(dpage) - chunk->pfn_first;
                 dst_addr = (dst_addr << PAGE_SHIFT) + chunk->bo->bo.offset;
 
@@ -862,7 +858,7 @@ nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
                         continue;
                 }
 
-                chunk = (void *)hmm_devmem_page_get_drvdata(page);
+                chunk = page->zone_device_data;
                 addr = page_to_pfn(page) - chunk->pfn_first;
                 addr = (addr + chunk->bo->bo.mem.start) << PAGE_SHIFT;
 
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 86aa4ec3404c..3d00e9550e77 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -584,36 +584,4 @@ static inline void hmm_mm_destroy(struct mm_struct *mm) {}
 static inline void hmm_mm_init(struct mm_struct *mm) {}
 #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
 
-#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
-/*
- * hmm_devmem_page_set_drvdata - set per-page driver data field
- *
- * @page: pointer to struct page
- * @data: driver data value to set
- *
- * Because page can not be on lru we have an unsigned long that driver can use
- * to store a per page field. This just a simple helper to do that.
- */
-static inline void hmm_devmem_page_set_drvdata(struct page *page,
-                                               unsigned long data)
-{
-        page->hmm_data = data;
-}
-
-/*
- * hmm_devmem_page_get_drvdata - get per page driver data field
- *
- * @page: pointer to struct page
- * Return: driver data value
- */
-static inline unsigned long hmm_devmem_page_get_drvdata(const struct page *page)
-{
-        return page->hmm_data;
-}
-#endif /* CONFIG_DEVICE_PRIVATE */
-#else /* IS_ENABLED(CONFIG_HMM) */
-static inline void hmm_mm_destroy(struct mm_struct *mm) {}
-static inline void hmm_mm_init(struct mm_struct *mm) {}
-#endif /* IS_ENABLED(CONFIG_HMM) */
-
 #endif /* LINUX_HMM_H */
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8ec38b11b361..f33a1289c101 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -158,7 +158,7 @@ struct page {
                 struct {        /* ZONE_DEVICE pages */
                         /** @pgmap: Points to the hosting device page map. */
                         struct dev_pagemap *pgmap;
-                        unsigned long hmm_data;
+                        void *zone_device_data;
                         unsigned long _zd_pad_1;        /* uses mapping */
                 };
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 17a39d40a556..c0e031c52db5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5886,12 +5886,12 @@ void __ref memmap_init_zone_device(struct zone *zone,
                 __SetPageReserved(page);
 
                 /*
-                 * ZONE_DEVICE pages union ->lru with a ->pgmap back
-                 * pointer and hmm_data.  It is a bug if a ZONE_DEVICE
-                 * page is ever freed or placed on a driver-private list.
+                 * ZONE_DEVICE pages union ->lru with a ->pgmap back pointer
+                 * and zone_device_data.  It is a bug if a ZONE_DEVICE page is
+                 * ever freed or placed on a driver-private list.
                  */
                 page->pgmap = pgmap;
-                page->hmm_data = 0;
+                page->zone_device_data = NULL;
 
                 /*
                  * Mark the block movable so that blocks are reserved for