Hello, all. Here's another round of block PIO cache coherency fix patchset. The previous try[1] was rejected because flush_dcache_page() was excessive and couldn't be called from irq context. A new cachetlb interface has been introduced - flush_kernel_dcache_page(), which is only responsible for flushing the kernel mapping and safe to call from irq context. The function is implemented only for parisc. This patchset adds implementation for arm. blk kmap wrappers have been dropped and calls to flush_kernel_dcache_page() have been directly added. Because flush_kernel_dcache_page() hasn't been implemented on many architectures, converting to such wrappers breaks cache coherency for such architectures. kmap should be updated after all archtectures with aliasing caches implement flush_kernel_dcache_page(). Russell, can you please verify arm's flush_kernel_dcache_page()? I tried to implement flush_anon_page() too but didn't know what to do with anon_vma object. It seems that a call to __cpuc_flush_user_range() should do the job but it requires vma->vm_flags to see whether it's an executable page. To access vma from anon mapped page, page->mapping:anon_vma->lock should be grabbed and probably the first vma on the list can be used, which is kind of complex. I think the options here are... * adding vma argument to flush_anon_page() * always flush for the worst vm_flags I have only compile tested. Please verify this fixes the coherency problem on arm. Jens, if everyone is happy with this, can you push this patchset through blk tree? As this change only adds calls to flush_kernel_dcache_page() which is currently implement only on parisc and arm, I think including this fix into 2.6.17 shouldn't cause too much trouble. Thanks. -- tejun [1] http://article.gmane.org/gmane.linux.kernel/367509 - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
