From: NeilBrown <neilb@suse.de>
To: "Paweł Brodacki" <pawel.brodacki@googlemail.com>
Cc: Alexander Lyakas <alex.bolshoy@gmail.com>, linux-raid@vger.kernel.org
Subject: Re: [md PATCH 08/23] md: don't set md arrays to readonly on shutdown.
Date: Sun, 22 Apr 2012 06:42:03 +1000 [thread overview]
Message-ID: <20120422064203.65eee938@notabene.brown> (raw)
In-Reply-To: <CACVpCE6UZvBia2VwRMaFhJJuB2quvKKQc1byLFRP4YPTE8LHSQ@mail.gmail.com>
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On Sat, 21 Apr 2012 17:18:58 +0200 Paweł Brodacki
<pawel.brodacki@googlemail.com> wrote:
> W dniu 20 kwietnia 2012 14:01 użytkownik NeilBrown <neilb@suse.de> napisał:
> > On Fri, 20 Apr 2012 13:30:39 +0200 Paweł Brodacki
> > <pawel.brodacki@googlemail.com> 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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next prev parent reply other threads:[~2012-04-21 20:42 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-14 4:40 [md PATCH 00/23] md patches heading for 3.4 NeilBrown
2012-03-14 4:40 ` [md PATCH 05/23] md/raid5: use atomic_dec_return() instead of atomic_dec() and atomic_read() NeilBrown
2012-03-14 4:40 ` [md PATCH 06/23] md: allow last device to be forcibly removed from RAID1/RAID10 NeilBrown
2012-03-14 4:40 ` [md PATCH 01/23] md/raid5: make sure reshape_position is cleared on error path NeilBrown
2012-03-14 4:40 ` [md PATCH 04/23] md: Use existed macros instead of numbers NeilBrown
2012-03-14 4:40 ` [md PATCH 03/23] md/raid5: removed unused 'added_devices' variable NeilBrown
2012-03-14 4:40 ` [md PATCH 02/23] md/raid10: remove unnecessary smp_mb() from end_sync_write NeilBrown
2012-03-14 4:40 ` [md PATCH 09/23] md/bitmap: ensure to load bitmap when creating via sysfs NeilBrown
2012-03-14 4:40 ` [md PATCH 13/23] md/raid10: handle merge_bvec_fn in member devices NeilBrown
2012-03-14 4:40 ` [md PATCH 10/23] md/raid1, raid10: avoid deadlock during resync/recovery NeilBrown
2012-03-14 4:40 ` [md PATCH 11/23] md: tidy up rdev_for_each usage NeilBrown
2012-03-14 4:40 ` [md PATCH 12/23] md: add proper merge_bvec handling to RAID0 and Linear NeilBrown
2012-03-14 4:40 ` [md PATCH 07/23] md: allow re-add to failed arrays NeilBrown
2012-03-14 4:40 ` [md PATCH 08/23] md: don't set md arrays to readonly on shutdown NeilBrown
2012-04-18 15:37 ` Alexander Lyakas
2012-04-18 17:44 ` Paweł Brodacki
2012-04-18 20:53 ` Alexander Lyakas
2012-04-18 22:48 ` NeilBrown
2012-04-19 9:11 ` Alexander Lyakas
2012-04-19 9:57 ` NeilBrown
2012-04-20 11:30 ` Paweł Brodacki
2012-04-20 12:01 ` NeilBrown
2012-04-21 15:18 ` Paweł Brodacki
2012-04-21 20:42 ` NeilBrown [this message]
2012-04-30 10:32 ` Paweł Brodacki
2012-04-20 16:26 ` John Robinson
2012-03-14 4:40 ` [md PATCH 14/23] md/raid1: handle merge_bvec_fn in member devices NeilBrown
2012-03-14 4:40 ` [md PATCH 22/23] md: fix clearing of the 'changed' flags for the bad blocks list NeilBrown
2012-03-14 4:40 ` [md PATCH 16/23] md/bitmap: remove some unused noise from bitmap.h NeilBrown
2012-03-14 4:40 ` [md PATCH 21/23] md/bitmap: discard CHUNK_BLOCK_SHIFT macro NeilBrown
2012-03-14 4:40 ` [md PATCH 19/23] md/bitmap: remove some pointless locking NeilBrown
2012-03-14 4:40 ` [md PATCH 20/23] md/bitmap: remove unnecessary indirection when allocating NeilBrown
2012-03-14 4:40 ` [md PATCH 17/23] md/bitmap: move printing of bitmap status to bitmap.c NeilBrown
2012-03-14 4:40 ` [md PATCH 15/23] md/raid10 - support resizing some RAID10 arrays NeilBrown
2012-03-14 6:17 ` keld
2012-03-14 6:27 ` NeilBrown
2012-03-14 7:51 ` David Brown
2012-03-14 8:32 ` NeilBrown
2012-03-14 10:20 ` David Brown
2012-03-14 12:37 ` keld
2012-03-14 4:40 ` [md PATCH 18/23] md/bitmap: change a 'goto' to a normal 'if' construct NeilBrown
2012-03-14 4:40 ` [md PATCH 23/23] md: Add judgement bb->unacked_exist in function md_ack_all_badblocks() NeilBrown
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