3.18-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andrey Ryabinin <aryabi...@virtuozzo.com> commit 70d78fe7c8b640b5acfad56ad341985b3810998a upstream. 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-aryabi...@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> Acked-by: Pavel Machek <pa...@ucw.cz> Acked-by: Oleg Nesterov <o...@redhat.com> Cc: Alexander Viro <v...@zeniv.linux.org.uk> Cc: Tejun Heo <t...@kernel.org> Cc: "Rafael J. Wysocki" <r...@rjwysocki.net> Cc: Michal Hocko <mho...@kernel.org> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/coredump.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/coredump.c +++ b/fs/coredump.c @@ -1,6 +1,7 @@ #include <linux/slab.h> #include <linux/file.h> #include <linux/fdtable.h> +#include <linux/freezer.h> #include <linux/mm.h> #include <linux/stat.h> #include <linux/fcntl.h> @@ -393,7 +394,9 @@ static int coredump_wait(int exit_code, if (core_waiters > 0) { struct core_thread *ptr; + freezer_do_not_count(); wait_for_completion(&core_state->startup); + freezer_count(); /* * Wait for all the threads to become inactive, so that * all the thread context (extended register state, like
