On Fri, Nov 15, 2013 at 02:42:05PM -0800, James Bottomley wrote: > On Fri, 2013-11-15 at 23:05 +0100, Helge Deller wrote: > > When a user page mapping is released via kunmap*() functions, the D-cache > > needs > > to be flushed via flush_dcache_page() to avoid D-cache aliasing issues. > > > > This patch fixes aio on the parisc platform (and probably others). > > This should be flush_kernel_dcache_page(). flush_dcache_page() is for > full coherency but for unmap, we know the page was coherent going in and > may have been modified by the kernel, so only the kernel view needs to > be sync'd. Technically, by the kernel API, the flush should be done > *before* unmapping. This would have mattered on parisc until we did > flush via tmpalias which means we no-longer care if the mapping for the > flush exists or not because we always recreate it via the tmpalias > pages.
On ARM, flush_kernel_dcache_page() actually assumes that the page is mapped. It avoids double flushing of highmem pages by not flushing in those cases where kunmap_atomic() already takes care of flushing. - Simon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
