fcf8935832
It was found that a number of offline memcgs were not freed because they were pinned by some charged pages that were present. Even "echo 1 > /proc/sys/vm/drop_caches" wasn't able to free those pages. These offline but not freed memcgs tend to increase in number over time with the side effect that percpu memory consumption as shown in /proc/meminfo also increases over time. In order to find out more information about those pages that pin offline memcgs, the page_owner feature is extended to print memory cgroup information especially whether the cgroup is offline or not. RCU read lock is taken when memcg is being accessed to make sure that it won't be freed. Link: https://lkml.kernel.org/r/20220202203036.744010-4-longman@redhat.com Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Rafael Aquini <aquini@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> 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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.