coredump: fix unfreezable coredumping task
authorAndrey Ryabinin <aryabinin@virtuozzo.com>
Thu, 10 Nov 2016 18:46:38 +0000 (10:46 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 11 Nov 2016 16:12:37 +0000 (08:12 -0800)
commit70d78fe7c8b640b5acfad56ad341985b3810998a
treeebcdf4e54b1c2ab369ab58a73573683cb04edf1e
parent60da81ea61201f43387793d1cc3f501609d922ed
coredump: fix unfreezable coredumping task

It could be not possible to freeze coredumping task when it waits for
'core_state->startup' completion, because threads are frozen in
get_signal() before they got a chance to complete 'core_state->startup'.

Inability to freeze a task during suspend will cause suspend to fail.
Also CRIU uses cgroup freezer during dump operation.  So with an
unfreezable task the CRIU dump will fail because it waits for a
transition from 'FREEZING' to 'FROZEN' state which will never happen.

Use freezer_do_not_count() to tell freezer to ignore coredumping task
while it waits for core_state->startup completion.

Link: http://lkml.kernel.org/r/1475225434-3753-1-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/coredump.c