linux-stable.git/kernel/cgroup/cgroup.c, branch v6.6.2

cgroup: fix build when CGROUP_SCHED is not enabled

2023-09-02T15:27:17+00:00

Sudip Mukherjee reports that the mips sb1250_swarm_defconfig build fails
with the current kernel.  It isn't actually MIPS-specific, it's just
that that defconfig does not have CGROUP_SCHED enabled like most configs
do, and as such shows this error:

  kernel/cgroup/cgroup.c: In function 'cgroup_local_stat_show':
  kernel/cgroup/cgroup.c:3699:15: error: implicit declaration of function 'cgroup_tryget_css'; did you mean 'cgroup_tryget'? [-Werror=implicit-function-declaration]
   3699 |         css = cgroup_tryget_css(cgrp, ss);
        |               ^~~~~~~~~~~~~~~~~
        |               cgroup_tryget
  kernel/cgroup/cgroup.c:3699:13: warning: assignment to 'struct cgroup_subsys_state *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
   3699 |         css = cgroup_tryget_css(cgrp, ss);
        |             ^

because cgroup_tryget_css() only exists when CGROUP_SCHED is enabled,
and the cgroup_local_stat_show() function should similarly be guarded by
that config option.

Move things around a bit to fix this all.

Fixes: d1d4ff5d11a5 ("cgroup: put cgroup_tryget_css() inside CONFIG_CGROUP_SCHED")
Reported-by: Sudip Mukherjee 
Cc: Miaohe Lin 
Cc: Tejun Heo 
Signed-off-by: Linus Torvalds

Merge tag 'cgroup-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2023-09-01T22:58:21+00:00

Pull cgroup updates from Tejun Heo:

 - Per-cpu cpu usage stats are now tracked

   This currently isn't printed out in the cgroupfs interface and can
   only be accessed through e.g. BPF. Should decide on a not-too-ugly
   way to show per-cpu stats in cgroupfs

 - cpuset received some cleanups and prepatory patches for the pending
   cpus.exclusive patchset which will allow cpuset partitions to be
   created below non-partition parents, which should ease the management
   of partition cpusets

 - A lot of code and documentation cleanup patches

 - tools/testing/selftests/cgroup/test_cpuset.c added

* tag 'cgroup-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (32 commits)
  cgroup: Avoid -Wstringop-overflow warnings
  cgroup:namespace: Remove unused cgroup_namespaces_init()
  cgroup/rstat: Record the cumulative per-cpu time of cgroup and its descendants
  cgroup: clean up if condition in cgroup_pidlist_start()
  cgroup: fix obsolete function name in cgroup_destroy_locked()
  Documentation: cgroup-v2.rst: Correct number of stats entries
  cgroup: fix obsolete function name above css_free_rwork_fn()
  cgroup/cpuset: fix kernel-doc
  cgroup: clean up printk()
  cgroup: fix obsolete comment above cgroup_create()
  docs: cgroup-v1: fix typo
  docs: cgroup-v1: correct the term of Page Cache organization in inode
  cgroup/misc: Store atomic64_t reads to u64
  cgroup/misc: Change counters to be explicit 64bit types
  cgroup/misc: update struct members descriptions
  cgroup: remove cgrp->kn check in css_populate_dir()
  cgroup: fix obsolete function name
  cgroup: use cached local variable parent in for loop
  cgroup: remove obsolete comment above struct cgroupstats
  cgroup: put cgroup_tryget_css() inside CONFIG_CGROUP_SCHED
  ...

cgroup: Avoid -Wstringop-overflow warnings

2023-08-17T21:55:05+00:00

Change the notation from pointer-to-array to pointer-to-pointer.
With this, we avoid the compiler complaining about trying
to access a region of size zero as an argument during function
calls.

This is a workaround to prevent the compiler complaining about
accessing an array of size zero when evaluating the arguments
of a couple of function calls. See below:

kernel/cgroup/cgroup.c: In function 'find_css_set':
kernel/cgroup/cgroup.c:1206:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
 1206 |         cset = find_existing_css_set(old_cset, cgrp, template);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/cgroup/cgroup.c:1206:16: note: referencing argument 3 of type 'struct cgroup_subsys_state *[0]'
kernel/cgroup/cgroup.c:1071:24: note: in a call to function 'find_existing_css_set'
 1071 | static struct css_set *find_existing_css_set(struct css_set *old_cset,
      |                        ^~~~~~~~~~~~~~~~~~~~~

With the change to pointer-to-pointer, the functions are not prevented
from being executed, and they will do what they have to do when
CGROUP_SUBSYS_COUNT == 0.

Address the following -Wstringop-overflow warnings seen when
built with ARM architecture and aspeed_g4_defconfig configuration
(notice that under this configuration CGROUP_SUBSYS_COUNT == 0):

kernel/cgroup/cgroup.c:1208:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
kernel/cgroup/cgroup.c:1258:15: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
kernel/cgroup/cgroup.c:6089:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]
kernel/cgroup/cgroup.c:6153:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=]

This results in no differences in binary output.

Link: https://github.com/KSPP/linux/issues/316
Signed-off-by: Gustavo A. R. Silva 
Reviewed-by: Kees Cook 
Signed-off-by: Tejun Heo

cgroup: fix obsolete function name in cgroup_destroy_locked()

2023-08-04T00:13:33+00:00

Since commit e76ecaeef65c ("cgroup: use cgroup_kn_lock_live() in other
cgroup kernfs methods"), cgroup_kn_lock_live() is used in cgroup kernfs
methods. Update corresponding comment.

Signed-off-by: Miaohe Lin 
Acked-by: Johannes Weiner 
Signed-off-by: Tejun Heo

cgroup: fix obsolete function name above css_free_rwork_fn()

2023-08-02T19:37:59+00:00

Since commit 8f36aaec9c92 ("cgroup: Use rcu_work instead of explicit rcu
and work item"), css_free_work_fn has been renamed to css_free_rwork_fn.
Update corresponding comment.

Signed-off-by: Miaohe Lin 
Signed-off-by: Tejun Heo

cgroup: clean up printk()

2023-08-02T19:36:24+00:00

Convert the only printk() to use pr_*() helper. No functional change.

Signed-off-by: Kamalesh Babulal 
Signed-off-by: Tejun Heo

cgroup: fix obsolete comment above cgroup_create()

2023-07-21T19:54:48+00:00

Since commit 743210386c03 ("cgroup: use cgrp->kn->id as the cgroup ID"),
cgrp is associated with its kernfs_node. Update corresponding comment.

Signed-off-by: Miaohe Lin 
Signed-off-by: Tejun Heo

Merge tag 'v6.5-rc2' into sched/core, to pick up fixes

2023-07-19T07:43:25+00:00

Sync with upstream fixes before applying EEVDF.

Signed-off-by: Ingo Molnar

cgroup: remove cgrp->kn check in css_populate_dir()

2023-07-17T18:44:56+00:00

cgroup_create() creates cgrp and assigns the kernfs_node to cgrp->kn,
then cgroup_mkdir() populates base and csses cft file by calling
css_populate_dir() and cgroup_apply_control_enable() with a valid
cgrp->kn. Check for NULL cgrp->kn, will always be false, remove it.

Signed-off-by: Kamalesh Babulal 
Signed-off-by: Tejun Heo

cgroup: fix obsolete function name

2023-07-17T18:38:58+00:00

cgroup_taskset_migrate() has been renamed to cgroup_migrate_execute() since
commit e595cd706982 ("cgroup: track migration context in cgroup_mgctx").
Update the corresponding comment.

Signed-off-by: Miaohe Lin 
Signed-off-by: Tejun Heo