linux-kernel - [ 002/173] freezer: PF_FREEZER_NOSIG should be cleared along with PF

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Message-Id: <20121228190330.511716895@decadent.org.uk>
Date:	Fri, 28 Dec 2012 20:03:32 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Oleg Nesterov <oleg@...hat.com>
Subject: [ 002/173] freezer: PF_FREEZER_NOSIG should be  cleared along with PF_NOFREEZE

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oleg Nesterov <oleg@...hat.com>

This patch is only for pre-v3.3 stable trees which backported
b40a7959 "freezer: exec should clear PF_NOFREEZE along with PF_KTHREAD".
v3.3+ doesn't need this fix.

b40a7959 is the trivial bugfix, but unfortunately I forgot that
until 34b087e4 "freezer: kill unused set_freezable_with_signal()"
there were another only-for-kernel-threads flag, PF_FREEZER_NOSIG,
which should be cleared as well.

See https://bugs.launchpad.net/ubuntu/+source/v86d/+bug/1080530
The freezer fails because it expects that a PF_FREEZER_NOSIG task
doesn't need a signal. Before b40a7959 it wrongly succeeds leaving
the PF_NOFREEZE | PF_FREEZER_NOSIG task unfrozen.

Reported-and-tested-by: Joseph Salisbury <joseph.salisbury@...onical.com>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
[bwh: Don't touch PF_FORKNOEXEC; it's cleared elsewhere]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1095,7 +1095,8 @@ int flush_old_exec(struct linux_binprm *
 	bprm->mm = NULL;		/* We're using it now */

 	set_fs(USER_DS);
-	current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD | PF_NOFREEZE);
+	current->flags &=
+		~(PF_RANDOMIZE | PF_KTHREAD | PF_NOFREEZE | PF_FREEZER_NOSIG);
 	flush_thread();
 	current->personality &= ~bprm->per_clear;

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