On Sat, 21 Apr 2012 17:18:58 +0200 Paweł Brodacki <pawel.brodacki@xxxxxxxxxxxxxx> wrote: > W dniu 20 kwietnia 2012 14:01 użytkownik NeilBrown <neilb@xxxxxxx> napisał: > > On Fri, 20 Apr 2012 13:30:39 +0200 Paweł Brodacki > > <pawel.brodacki@xxxxxxxxxxxxxx> wrote: > >> > >> The way I read the message agrees with Alexander's perception. My > >> impression from reading the commit message is, that normal shutdown > >> may result in unclean array, which I would perceive as a regression. > > > > I don't think you'll find the word "normal" in the original message :-) > > > Neil, I respect you and admire your work and all, but I think you are > having good time with us and this commit message, aren't you? :) "For what, we ask, is life - without a touch of poetry in it". Maybe not an entirely relevant quote, but it is the first that came to mind. "What's life without whimsy?" Would be a slightly more modern quote. Can you place them without google's help? > > >> > >> I would really appreciate clear statement, whether this behaviour > >> (writeback during shutdown, with possibility of poweroff/reboot while > >> array is dirty) can or cannot occur during normal shutdown process. > > > > Define "normal". > > If you kill any processes that could generate write-out, and then do a > > 'sync', then everything should be fine. > > > I think "normal shutdown" can be defined for the purpose of this > discussion as whatever /sbin/shutdown does. > > If I run /sbin/shutdown -h now, it is a normal shutdown. If I do fancy > stuff echoing cute strings and integers into various parts of /proc > and /sys, push magic buttons and/or pull cables at random, it' is not > a normal shutdown. > > > I suspend a "normal" shutdown sequence does this. > > > > NeilBrown > > > > I smell a hint here. > > man shutdown: > "shutdown arranges for the system to be brought down in a safe way." > Define safe... > > Neil, could you point us to a bug report which inspired you to write > this patch? My google fu failed me and I was able to find just one bug > entry from before 2 yerars, and even that hit is of dubious relevance. > > Pretty please with sugar on top? > https://bugzilla.novell.com/show_bug.cgi?id=713148 But that is against our "enterprise" product so is not globally visible :-( But it gave me some search-term hints so: http://lists.debian.org/debian-kernel/2011/05/msg00264.html http://www.issociate.de/board/post/491554/Kernel_BUG.html http://www.gossamer-threads.com/lists/xen/devel/174884?do=post_view_threaded https://lkml.org/lkml/2008/11/24/414 http://comments.gmane.org/gmane.linux.raid/20710 The important elements are: 1/ you see "md: stopping all devices". This means that "reboot" has really started. This is printed by mds reboot notifier. 2/ A stack trace showing something submitting IO. In the first link it is bdi_writeback_task In the second it is kjournald This pattern can only happen on an unclean shutdown. NeilBrown
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