Messages in this thread Patch in this message | | | Date | Mon, 21 Nov 2005 16:25:58 +0000 | From | Russell King <> | Subject | Re: 2.6.15-rc1-mm2 -- Bad page state at free_hot_cold_page (in process 'aplay', page c18eef30) |
| |
On Mon, Nov 21, 2005 at 05:17:12PM +0100, Takashi Iwai wrote: > Now another question arises: Which is the recommended method for > mmapping RAM pages, vma nopage callback or remap_pfn_range()? > > IIRC, in the ealier versions, the former was recommended because > remap_page_range() with page-reserve was regarded as a hack. > But, looking through these changes, I feel that remap_pfn_range() is > better (easier and stabler) than vma nopage...
And this brings up the question of this age old patch:
diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x '*.orig' -x '*.rej' -r orig/arch/i386/kernel/pci-dma.c linux/arch/i386/kernel/pci-dma.c --- orig/arch/i386/kernel/pci-dma.c Mon Apr 4 22:52:57 2005 +++ linux/arch/i386/kernel/pci-dma.c Mon Apr 4 22:44:45 2005 @@ -50,7 +50,7 @@ void *dma_alloc_coherent(struct device * ret = (void *)__get_free_pages(gfp, order); if (ret != NULL) { - memset(ret, 0, size); + memset(ret, 0, PAGE_ALIGN(size)); *dma_handle = virt_to_phys(ret); } return ret; diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x '*.orig' -x '*.rej' -r orig/include/asm-i386/dma-mapping.h linux/include/asm-i386/dma-mapping.h --- orig/include/asm-i386/dma-mapping.h Mon Apr 4 22:54:41 2005 +++ linux/include/asm-i386/dma-mapping.h Mon Apr 4 22:48:11 2005 @@ -16,6 +16,23 @@ void *dma_alloc_coherent(struct device * void dma_free_coherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle); +static inline int +dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma, + void *vaddr, dma_addr_t handle, size_t size) +{ + unsigned long offset = vma->vm_pgoff, usize; + + size = PAGE_ALIGN(size) >> PAGE_SHIFT; + usize = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; + + if (offset >= size || usize > (size - offset)) + return -ENXIO; + + return remap_page_range(vma, vma->vm_start, + __pa(vaddr) + (offset << PAGE_SHIFT), + usize << PAGE_SHIFT, vma->vm_page_prot); +} + static inline dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size, enum dma_data_direction direction) which provides the dma mmap API which presently is ARM-only on to x86.
Note: the first part of this patch should probably be applied anyway if you're mmaping dma_alloc_coherent pages to userspace to ensure that information is not leaked from kernel context.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |