On Wed, 9 Jul 2014 00:40:17 +0400 Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: > On Tue, Jul 08, 2014 at 01:19:20PM -0700, Andrew Morton wrote: > > On Tue, 8 Jul 2014 23:21:51 +0400 Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: > > > > > Otherwise we may not notice that pte was softdirty because pte_mksoft_dirty > > > helper _returns_ new pte but not modifies argument. > > > > When fixing a bug, please describe the end-user visible effects of that > > bug. > > > > [for the 12,000th time :(] > > "we may not notice that pte was softdirty" I thought it's enough, because > that's the effect user sees -- pte is not dirtified where it should. > > Really sorry Andrew if I were not clear enough. What about: In case if page > fault happend on dirty filemapping the newly created pte may not > notice if old one were already softdirtified because pte_mksoft_dirty > doesn't modify its argument but rather returns new pte value. The user doesn't know or care about pte bits. What actually *happens*? Does criu migration hang? Does it lose data? Does it take longer? IOW, what would an end-user's bug report look like? It's important to think this way because a year from now some person we've never heard of may be looking at a user's bug report and wondering whether backporting this patch will fix it. Amongst other reasons. -- 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>