On Wed, Nov 19, 2008 at 03:25:59PM +1100, Nick Piggin wrote: > The solution either involves synchronising forks and get_user_pages, > or probably better, to do copy on fork rather than COW in the case > that we detect a page is subject to get_user_pages. The trick is in > the details :) We already have a patch that works. The only trouble here is get_user_pages_fast, it breaks the fix for fork, the current ksm (that is safe against get_user_pages but can't be safe against get_user_pages_fast) and even migrate.c memory-corrupts against O_DIRECT after the introduction of get_user_pages_fast. So I recommend focusing on how to fix get_user_pages_fast for any of the 3 broken pieces, then hopefully the same fix will work for the other two. fork is special in that it even breaks against get_user_pages but again we've a fix for that. The only problem without a solution is how to serialize against get_user_pages_fast. A brlock was my proposal, not nice but still better than backing out get_user_pages_fast. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
