CMA-allocated memory must be freed by an exact mirror call to
dma_release_from_contiguous(). It cannot be freed page-by-page as was
previously believed without severe memory leakage.

This page records the address and size of every allocated memory chunk
so they can be properly freed when needed.

Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
---
 drivers/gpu/drm/nouveau/core/subdev/fb/ramgk20a.c | 74 ++++++++++++++---------
 1 file changed, 46 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/core/subdev/fb/ramgk20a.c 
b/drivers/gpu/drm/nouveau/core/subdev/fb/ramgk20a.c
index 7effd1a63458..5904af52e6d6 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/fb/ramgk20a.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/fb/ramgk20a.c
@@ -28,28 +28,34 @@
 #include <linux/types.h>
 #include <linux/dma-contiguous.h>

+struct gk20a_mem_chunk {
+       struct list_head list;
+       struct page *pages;
+       u32 npages;
+};
+
+struct gk20a_mem {
+       struct nouveau_mem base;
+       struct list_head head;
+};
+
 static void
 gk20a_ram_put(struct nouveau_fb *pfb, struct nouveau_mem **pmem)
 {
        struct device *dev = nv_device_base(nv_device(pfb));
-       struct nouveau_mem *mem = *pmem;
-       int i;
+       struct gk20a_mem *mem = container_of(*pmem, struct gk20a_mem, base);
+       struct gk20a_mem_chunk *chunk, *n;

        *pmem = NULL;
        if (unlikely(mem == NULL))
                return;

-       for (i = 0; i < mem->size; i++) {
-               struct page *page;
-
-               if (mem->pages[i] == 0)
-                       break;
-
-               page = pfn_to_page(mem->pages[i] >> PAGE_SHIFT);
-               dma_release_from_contiguous(dev, page, 1);
+       list_for_each_entry_safe(chunk, n, &mem->head, list) {
+               dma_release_from_contiguous(dev, chunk->pages, chunk->npages);
+               kfree(chunk);
        }

-       kfree(mem->pages);
+       kfree(mem->base.pages);
        kfree(mem);
 }

@@ -58,9 +64,8 @@ gk20a_ram_get(struct nouveau_fb *pfb, u64 size, u32 align, 
u32 ncmin,
             u32 memtype, struct nouveau_mem **pmem)
 {
        struct device *dev = nv_device_base(nv_device(pfb));
-       struct nouveau_mem *mem;
+       struct gk20a_mem *mem;
        int type = memtype & 0xff;
-       dma_addr_t dma_addr;
        int npages;
        int order;
        int i;
@@ -95,44 +100,57 @@ gk20a_ram_get(struct nouveau_fb *pfb, u64 size, u32 align, 
u32 ncmin,
        if (!mem)
                return -ENOMEM;

-       mem->size = npages;
-       mem->memtype = type;
+       mem->base.size = npages;
+       mem->base.memtype = type;

-       mem->pages = kzalloc(sizeof(dma_addr_t) * npages, GFP_KERNEL);
-       if (!mem) {
+       mem->base.pages = kzalloc(sizeof(dma_addr_t) * npages, GFP_KERNEL);
+       if (!mem->base.pages) {
                kfree(mem);
                return -ENOMEM;
        }

+       INIT_LIST_HEAD(&mem->head);
+
+       *pmem = &mem->base;
+
        while (npages) {
-               struct page *pages;
+               struct gk20a_mem_chunk *chunk;
+               dma_addr_t addr;
                int pos = 0;

                /* don't overflow in case size is not a multiple of ncmin */
                if (ncmin > npages)
                        ncmin = npages;

-               pages = dma_alloc_from_contiguous(dev, ncmin, order);
-               if (!pages) {
-                       gk20a_ram_put(pfb, &mem);
+               chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+               if (!chunk) {
+                       gk20a_ram_put(pfb, pmem);
                        return -ENOMEM;
                }

-               dma_addr = (dma_addr_t)(page_to_pfn(pages) << PAGE_SHIFT);
+               chunk->pages = dma_alloc_from_contiguous(dev, ncmin, order);
+               if (!chunk->pages) {
+                       kfree(chunk);
+                       gk20a_ram_put(pfb, pmem);
+                       return -ENOMEM;
+               }

-               nv_debug(pfb, "  alloc count: %x, order: %x, addr: %pad\n", 
ncmin,
-                        order, &dma_addr);
+               chunk->npages = ncmin;
+               list_add_tail(&chunk->list, &mem->head);
+
+               addr = (dma_addr_t)(page_to_pfn(chunk->pages) << PAGE_SHIFT);
+
+               nv_debug(pfb, "  alloc count: %x, order: %x, addr: %pad\n",
+                        ncmin, order, &addr);

                for (i = 0; i < ncmin; i++)
-                       mem->pages[pos + i] = dma_addr + (PAGE_SIZE * i);
+                       mem->base.pages[pos + i] = addr + (PAGE_SIZE * i);

                pos += ncmin;
                npages -= ncmin;
        }

-       mem->offset = (u64)mem->pages[0];
-
-       *pmem = mem;
+       mem->base.offset = (u64)mem->base.pages[0];

        return 0;
 }
-- 
1.9.2

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