linux-kernel - [PATCH 2/6] oom: Get rid of sparse warnings

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Date:	Mon, 6 Feb 2012 20:29:35 +0400
From:	Anton Vorontsov <anton.vorontsov@...aro.org>
To:	Oleg Nesterov <oleg@...hat.com>,
	Greg KH <gregkh@...uxfoundation.org>
Cc:	Arve Hjønnevåg <arve@...roid.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	San Mehat <san@...gle.com>, Colin Cross <ccross@...roid.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, kernel-team@...roid.com,
	linaro-kernel@...ts.linaro.org
Subject: [PATCH 2/6] oom: Get rid of sparse warnings

Sparse flood makes it hard to catch newly-introduced warnings. So let's
fix the the sparse warnings in the oom killer:

  CHECK   mm/oom_kill.c
  mm/oom_kill.c:139:20: warning: context imbalance in
	  '__find_lock_task_mm' - wrong count at exit
  mm/oom_kill.c:771:9: warning: context imbalance in 'out_of_memory' -
	  different lock contexts for basic block

The first one is fixed by assuring sparse that we know that we exit
with the lock held.

The second one is caused by the fact that sparse isn't smart enough
to handle noreturn attribute.

Signed-off-by: Anton Vorontsov <anton.vorontsov@...aro.org>
---
 mm/oom_kill.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 0ebb383..49569b6 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -142,8 +142,14 @@ struct task_struct *__find_lock_task_mm(struct task_struct *p)
 
 	do {
 		task_lock(t);
-		if (likely(t->mm))
+		if (likely(t->mm)) {
+			/*
+			 * Shut up sparse: we do know that we exit w/ the
+			 * task locked.
+			 */
+			__release(&t->alloc_loc);
 			return t;
+		}
 		task_unlock(t);
 	} while_each_thread(p, t);
 
@@ -766,6 +772,7 @@ retry:
 		dump_header(NULL, gfp_mask, order, NULL, mpol_mask);
 		read_unlock(&tasklist_lock);
 		panic("Out of memory and no killable processes...\n");
+		return;
 	}
 
 	if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,
-- 
1.7.7.6

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