Michal Koutný 46307fd6e2 cgroup: Reorganize css_set_lock and kernfs path processing
The commit 74e4b956eb incorrectly wrapped kernfs_walk_and_get
(might_sleep) under css_set_lock (spinlock). css_set_lock is needed by
__cset_cgroup_from_root to ensure stable cset->cgrp_links but not for
kernfs_walk_and_get.

We only need to make sure that the returned root_cgrp won't be freed
under us. This is given in the case of global root because it is static
(cgrp_dfl_root.cgrp). When the root_cgrp is lower in the hierarchy, it
is pinned by cgroup_ns->root_cset (and `current` task cannot switch
namespace asynchronously so ns_proxy pins cgroup_ns).

Note this reasoning won't hold for root cgroups in v1 hierarchies,
therefore create a special-cased helper function just for the default
hierarchy.

Fixes: 74e4b956eb ("cgroup: Honor caller's cgroup NS when resolving path")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2022-10-10 10:23:18 -10:00
2022-09-28 09:02:20 +02:00
2022-09-26 12:37:21 -04:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00

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.
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