0008454e8f
When I initially examined the function current_cgns_cgroup_from_root(), I was perplexed by its lack of holding cgroup_mutex. However, after Michal explained the reason[0] to me, I realized that it already holds the namespace_sem. I believe this intricacy could also confuse others, so it would be advisable to include an annotation for clarification. After we replace the cgroup_mutex with RCU read lock, if current doesn't hold the namespace_sem, the root cgroup will be NULL. So let's add a WARN_ON_ONCE() for it. [0]. https://lore.kernel.org/bpf/afdnpo3jz2ic2ampud7swd6so5carkilts2mkygcaw67vbw6yh@5b5mncf7qyet Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Michal Koutny <mkoutny@suse.com> Signed-off-by: Tejun Heo <tj@kernel.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.