On Wed, Sep 27, 2017 at 11:23:52AM +0100, Robin Murphy wrote: > > I found that debug_dma_alloc_coherent() and debug_dma_free_coherent() > > assume that dma_alloc_coherent() always returns a linear address. > > However it's possible that dma_alloc_coherent() returns a non-linear > > address. In this case, page_to_pfn(virt_to_page(virt)) will return an > > incorrect pfn. If the pfn is valid and mapped as a COW page, > > we will hit the warning when doing wp_page_copy(). Hmm, can the debug code assume anything? Right now you're just patching it from supporting linear and vmalloc. But what about other potential mapping types? > > + entry->pfn = is_vmalloc_addr(virt) ? vmalloc_to_pfn(virt) : > > + page_to_pfn(virt_to_page(virt)); Please use normal if/else conditionsals: if (is_vmalloc_addr(virt)) entry->pfn = vmalloc_to_pfn(virt); else entry->pfn = page_to_pfn(virt_to_page(virt)); > > + .pfn = is_vmalloc_addr(virt) ? vmalloc_to_pfn(virt) : > > + page_to_pfn(virt_to_page(virt)), Same here. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
