On Fri 28-10-11 14:34:31, Kazuya Mio wrote: > 2011/10/25 22:40, Jan Kara wrote: > > Please no. Generally this boils down to what do we do with dirty data > >when there's error in writing them out. Currently we just throw them away > >(e.g. in media error case) but I don't think that's a generally good thing > >because e.g. admin may want to copy the data to other working storage or > >so. So I think we should rather keep the data and provide a mechanism for > >userspace to ask kernel to get rid of the data (so that we don't eventually > >run OOM). > > I see. I agree with you. > > >>Do you have any ideas? > > So the question is what would you like to achieve. If you just want to > >unblock a thread then a solution would be to make a thread at > >balance_dirty_pages() killable. If generally you want to get rid of dirty > >memory, then I don't have a really good answer but throwing dirty data away > >seems like a bad answer to me. > > The problem is that we cannot unmount the corrupted filesystem due to > un-killable dd process. We must bring down the system to resume the service > with no dirty pages. I think it is important for the service continuity > to be able to kill the thread handling in balance_dirty_pages(). Sure. Then allowing a process to be killed while waiting in balance_dirty_pages() would solve your problem. That can be done relatively easily. I can write the patch, just now the code is under rewrite from IO-less dirty throttling patches so I'll wait for a while for it to settle down. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
