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From: Michal Hocko <mhocko@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>,
	Konstantin Khlebnikov <khlebnikov@openvz.org>,
	Oleg Nesterov <oleg@redhat.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	Rusty Russell <rusty@rustcorp.com.au>,
	Tejun Heo <htejun@gmail.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/2] lguest: move process freezing before pending signals check
Date: Tue, 27 Sep 2011 08:56:03 +0200	[thread overview]
Message-ID: <e213ea00900cba783f228eb4234ad929a05d4359.1317110948.git.mhocko@suse.cz> (raw)
In-Reply-To: <cover.1317110948.git.mhocko@suse.cz>

run_guest tries to freeze the current process after it has handled
pending interrupts and before it calls lguest_arch_run_guest.
This doesn't work nicely if the task has been killed while being frozen
and when we want to handle that signal as soon as possible.
Let's move try_to_freeze before we check for pending signal so that we
can get out of the loop as soon as possible.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
---
 drivers/lguest/core.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index 2535933..e7dda91 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -232,6 +232,13 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
 			}
 		}
 
+		/*
+		 * All long-lived kernel loops need to check with this horrible
+		 * thing called the freezer.  If the Host is trying to suspend,
+		 * it stops us.
+		 */
+		try_to_freeze();
+
 		/* Check for signals */
 		if (signal_pending(current))
 			return -ERESTARTSYS;
@@ -246,13 +253,6 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
 			try_deliver_interrupt(cpu, irq, more);
 
 		/*
-		 * All long-lived kernel loops need to check with this horrible
-		 * thing called the freezer.  If the Host is trying to suspend,
-		 * it stops us.
-		 */
-		try_to_freeze();
-
-		/*
 		 * Just make absolutely sure the Guest is still alive.  One of
 		 * those hypercalls could have been fatal, for example.
 		 */
-- 
1.7.5.4


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  reply	other threads:[~2011-09-27 18:10 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-27  8:09 [PATCH 0/2] oom: fix livelock when frozen task is selected Michal Hocko
2011-09-27  6:56 ` Michal Hocko [this message]
2011-10-12  6:55   ` [PATCH 1/2] lguest: move process freezing before pending signals check Michal Hocko
2011-10-12 23:57     ` Rusty Russell
2011-10-13  5:48       ` Michal Hocko
2011-09-27  8:01 ` [PATCH 2/2] oom: do not live lock on frozen tasks Michal Hocko
2011-09-27 18:35   ` [patch] oom: thaw threads if oom killed thread is frozen before deferring David Rientjes
2011-09-28 10:44     ` Michal Hocko
2011-09-29 11:51       ` Michal Hocko
2011-09-29 12:05         ` Oleg Nesterov
2011-09-29 13:02           ` Michal Hocko
2011-09-29 16:32             ` Michal Hocko
2011-09-29 16:37             ` Oleg Nesterov
2011-09-29 18:00               ` Michal Hocko
2011-09-30  1:51                 ` Tejun Heo
2011-09-30  7:41                   ` Michal Hocko
2011-09-30  7:46                     ` Tejun Heo
2011-09-30  8:04                       ` Michal Hocko
2011-09-30 15:30                 ` Oleg Nesterov
2011-10-28 22:23   ` [PATCH 2/2] oom: do not live lock on frozen tasks Andrew Morton
2011-10-29  9:01     ` Michal Hocko

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