From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Patch "hung_task: fix false positive during vfork" has been added to the 3.1-stable tree To: msb@chromium.org,akpm@linux-foundation.org,gregkh@suse.de,jkacur@redhat.com,levinsasha928@gmail.com,mingo@elte.hu,peterz@infradead.org,torvalds@linux-foundation.org Cc: , From: Date: Thu, 05 Jan 2012 11:25:08 -0800 Message-ID: <1325791508636@kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ASCII Content-Transfer-Encoding: 8bit List-ID: This is a note to let you know that I've just added the patch titled hung_task: fix false positive during vfork to the 3.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: hung_task-fix-false-positive-during-vfork.patch and it can be found in the queue-3.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From f9fab10bbd768b0e5254e53a4a8477a94bfc4b96 Mon Sep 17 00:00:00 2001 From: Mandeep Singh Baines Date: Tue, 3 Jan 2012 14:41:13 -0800 Subject: hung_task: fix false positive during vfork From: Mandeep Singh Baines commit f9fab10bbd768b0e5254e53a4a8477a94bfc4b96 upstream. vfork parent uninterruptibly and unkillably waits for its child to exec/exit. This wait is of unbounded length. Ignore such waits in the hung_task detector. Signed-off-by: Mandeep Singh Baines Reported-by: Sasha Levin LKML-Reference: <1325344394.28904.43.camel@lappy> Cc: Linus Torvalds Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Andrew Morton Cc: John Kacur Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/hung_task.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -74,11 +74,17 @@ static void check_hung_task(struct task_ /* * Ensure the task is not frozen. - * Also, when a freshly created task is scheduled once, changes - * its state to TASK_UNINTERRUPTIBLE without having ever been - * switched out once, it musn't be checked. + * Also, skip vfork and any other user process that freezer should skip. */ - if (unlikely(t->flags & PF_FROZEN || !switch_count)) + if (unlikely(t->flags & (PF_FROZEN | PF_FREEZER_SKIP))) + return; + + /* + * When a freshly created task is scheduled once, changes its state to + * TASK_UNINTERRUPTIBLE without having ever been switched out once, it + * musn't be checked. + */ + if (unlikely(!switch_count)) return; if (switch_count != t->last_switch_count) { Patches currently in stable-queue which might be from msb@chromium.org are queue-3.1/hung_task-fix-false-positive-during-vfork.patch queue-3.1/cgroups-fix-a-css_set-not-found-bug-in-cgroup_attach_proc.patch