On Tue, 2010-02-02 at 13:44 -0800, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > From: anfei zhou <anfei.zhou@xxxxxxxxx> > > The cache alias problem will happen if the changes of user shared mapping > is not flushed before copying, then user and kernel mapping may be mapped > into two different cache line, it is impossible to guarantee the coherence > after iov_iter_copy_from_user_atomic. So the right steps should be: > > flush_dcache_page(page); This is likely unnecessary if the page has come down a standard path ... for fuse, it is possible it didn't go through __get_user_pages(). > kmap_atomic(page); > write to page; > kunmap_atomic(page); > flush_dcache_page(page); > > More precisely, we might create two new APIs flush_dcache_user_page and > flush_dcache_kern_page to replace the two flush_dcache_page accordingly. We already have one of those: flush_kernel_dcache_page(). James -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
