ARM: DMA: Fix struct page iterator in dma_cache_maint() to work with sparsemem

Subhash Jadavani reported this partial backtrace:
  Now consider this call stack from MMC block driver (this is on the ARMv7
  based board):

  [<c001b50c>] (v7_dma_inv_range+0x30/0x48) from [<c0017b8c>] (dma_cache_maint_page+0x1c4/0x24c)
  [<c0017b8c>] (dma_cache_maint_page+0x1c4/0x24c) from [<c0017c28>] (___dma_page_cpu_to_dev+0x14/0x1c)
  [<c0017c28>] (___dma_page_cpu_to_dev+0x14/0x1c) from [<c0017ff8>] (dma_map_sg+0x3c/0x114)

This is caused by incrementing the struct page pointer, and running off
the end of the sparsemem page array.  Fix this by incrementing by pfn
instead, and convert the pfn to a struct page.

Cc: <stable@vger.kernel.org>
Suggested-by: James Bottomley <JBottomley@Parallels.com>
Tested-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 6b2fb87c8698a99254bdd56c0e4c2bf146994da5..076c26d43864f8a5b3da49ac7231a62e8edde0c2 100644 (file)
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -774,25 +774,27 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset,
        size_t size, enum dma_data_direction dir,
        void (*op)(const void *, size_t, int))
 {
+       unsigned long pfn;
+       size_t left = size;
+
+       pfn = page_to_pfn(page) + offset / PAGE_SIZE;
+       offset %= PAGE_SIZE;
+
        /*
         * A single sg entry may refer to multiple physically contiguous
         * pages.  But we still need to process highmem pages individually.
         * If highmem is not configured then the bulk of this loop gets
         * optimized out.
         */
-       size_t left = size;
        do {
                size_t len = left;
                void *vaddr;
 
+               page = pfn_to_page(pfn);
+
                if (PageHighMem(page)) {
-                       if (len + offset > PAGE_SIZE) {
-                               if (offset >= PAGE_SIZE) {
-                                       page += offset / PAGE_SIZE;
-                                       offset %= PAGE_SIZE;
-                               }
+                       if (len + offset > PAGE_SIZE)
                                len = PAGE_SIZE - offset;
-                       }
                        vaddr = kmap_high_get(page);
                        if (vaddr) {
                                vaddr += offset;
@@ -809,7 +811,7 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset,
                        op(vaddr, len, dir);
                }
                offset = 0;
-               page++;
+               pfn++;
                left -= len;
        } while (left);
 }