From: Josh Boyer <jwboyer@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Subject: 3.0-git15 Atomic scheduling in pidmap_init
Date: Mon, 1 Aug 2011 11:46:37 -0400 [thread overview]
Message-ID: <20110801154636.GA2096@zod.bos.redhat.com> (raw)
We're seeing a scheduling while atomic backtrace in rawhide from pidmap_init
(https://bugzilla.redhat.com/show_bug.cgi?id=726877). While this seems
mostly harmless given that there isn't anything else to schedule to at
this point, I do wonder why things are marked as needing rescheduled so
early.
We get to might_sleep through the might_sleep_if call in
slab_pre_alloc_hook because both kzalloc and KMEM_CACHE are called with
GFP_KERNEL. That eventually has a call chain like:
might_resched->_cond_resched->should_resched
which apparently returns true. Why the initial thread says it should
reschedule at this point, I'm not sure.
I tried cheating by making the kzalloc call in pidmap_init use GFP_IOFS
instead of GFP_KERNEL to avoid the might_sleep_if call, and that worked
but I can't do the same for the kmalloc calls in kmem_cache_create, so
getting to the bottom of why should_resched is returning true seems to
be a better approach.
josh
next reply other threads:[~2011-08-01 15:46 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-01 15:46 Josh Boyer [this message]
2011-08-04 11:46 ` Josh Boyer
2011-08-04 14:04 ` Paul E. McKenney
2011-08-04 15:06 ` Josh Boyer
2011-08-04 16:26 ` Paul E. McKenney
2011-08-04 17:31 ` Josh Boyer
2011-08-05 1:19 ` Josh Boyer
2011-08-05 6:56 ` Paul E. McKenney
2011-08-05 14:22 ` Josh Boyer
2011-08-05 17:08 ` Frederic Weisbecker
2011-08-05 22:26 ` Paul E. McKenney
2011-08-05 23:12 ` Frederic Weisbecker
2011-08-08 2:09 ` Paul E. McKenney
2011-08-08 2:55 ` Frederic Weisbecker
2011-08-08 3:10 ` Paul E. McKenney
2011-08-09 11:35 ` Frederic Weisbecker
2011-08-10 12:45 ` Josh Boyer
2011-08-10 14:53 ` Frederic Weisbecker
2011-08-10 15:03 ` Josh Boyer
2011-08-14 23:04 ` Paul E. McKenney
2011-08-15 14:04 ` Josh Boyer
2011-08-15 15:20 ` Paul E. McKenney
2011-08-17 22:37 ` Josh Boyer
2011-08-17 22:49 ` Paul E. McKenney
2011-08-17 23:02 ` Josh Boyer
2011-08-17 23:06 ` Frederic Weisbecker
2011-08-17 23:17 ` Josh Boyer
2011-08-18 18:35 ` Paul E. McKenney
2011-08-18 19:11 ` Josh Boyer
2011-08-18 21:00 ` Andrew Morton
2011-08-18 21:23 ` Paul E. McKenney
2011-08-18 21:55 ` Paul E. McKenney
2011-08-18 22:21 ` Josh Boyer
2011-08-18 23:01 ` Paul E. McKenney
2011-08-24 22:45 ` Frederic Weisbecker
2011-08-24 23:12 ` Paul E. McKenney
2011-08-24 23:34 ` Frederic Weisbecker
2011-08-24 23:57 ` Paul E. McKenney
2011-08-18 22:19 ` Josh Boyer
2011-08-18 23:16 ` Paul E. McKenney
2011-08-18 23:27 ` Andrew Morton
2011-08-19 0:38 ` Paul E. McKenney
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