mm/page_owner: record task command name

The page_owner information currently includes the pid of the calling
task.  That is useful as long as the task is still running.  Otherwise,
the number is meaningless.  To have more information about the
allocating tasks that had exited by the time the page_owner information
is retrieved, we need to store the command name of the task.

Add a new comm field into page_owner structure to store the command name
and display it when the page_owner information is retrieved.

Link: https://lkml.kernel.org/r/20220202203036.744010-5-longman@redhat.com


Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>