On Fri, Dec 07, 2012 at 03:49:22PM +0100, Oleg Nesterov wrote:

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 <redacted>
Cc: stable@vger.kernel.org # pre v3.3 if commit b40a7959 was taken

From what I can tell, 3.0-stable didn't take this patch, so it should be

fine.  Ben, I don't know about 3.2, you should check this.

Oleg, thanks for doing this work, much appreciated.

greg k-h