The patch titled
dm: work around mempool_alloc, bio_alloc_bioset deadlocks
has been removed from the -mm tree. Its filename is
md-work-around-mempool_alloc-bio_alloc_bioset-deadlocks.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: dm: work around mempool_alloc, bio_alloc_bioset deadlocks
From: "Pavel Mironchik" <tibor0@xxxxxxxxx>
This patch works around a complex dm-related deadlock/livelock down in the
mempool allocator.
Alasdair said:
Several dm targets suffer from this.
Mempools are not yet used correctly everywhere in device-mapper: they can
get shared when devices are stacked, and some targets share them across
multiple instances. I made fixing this one of the prerequisites for this
patch:
md-dm-reduce-stack-usage-with-stacked-block-devices.patch
which in some cases makes people more likely to hit the problem.
There's been some progress on this recently with (unfinished) dm-crypt
patches at:
http://www.kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/
(dm-crypt-move-io-to-workqueue.patch plus dependencies)
and:
I've no problems with a temporary workaround like that, but Milan Broz (a
new Redhat developer in the Czech Republic) has started reviewing all the
mempool usage in device-mapper so I'm expecting we'll soon have a proper fix
for this associated problems. [He's back from holiday at the start of next
week.]
For now, this sad-but-safe little patch will allow the machine to recover.
[akpm@xxxxxxxx: rewrote changelog]
Cc: Alasdair G Kergon <agk@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/mempool.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff -puN mm/mempool.c~md-work-around-mempool_alloc-bio_alloc_bioset-deadlocks mm/mempool.c
--- a/mm/mempool.c~md-work-around-mempool_alloc-bio_alloc_bioset-deadlocks
+++ a/mm/mempool.c
@@ -238,8 +238,13 @@ repeat_alloc:
init_wait(&wait);
prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
smp_mb();
- if (!pool->curr_nr)
- io_schedule();
+ if (!pool->curr_nr) {
+ /*
+ * FIXME: this should be io_schedule(). The timeout is there
+ * as a workaround for some DM problems in 2.6.18.
+ */
+ io_schedule_timeout(5*HZ);
+ }
finish_wait(&pool->wait, &wait);
goto repeat_alloc;
_
Patches currently in -mm which might be from tibor0@xxxxxxxxx are
origin.patch
--
VGER BF report: U 0.501768
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