kernel.git/kernel/cgroup/cgroup.c, branch linux-5.19.y

cgroup: Honor caller's cgroup NS when resolving path

2022-10-24T07:58:04Z

[ Upstream commit 74e4b956eb1cac0e4c10c240339b1bbfbc9a4c48 ] cgroup_get_from_path() is not widely used function. Its callers presume the path is resolved under cgroup namespace. (There is one caller currently and resolving in init NS won't make harm (netfilter). However, future users may be subject to different effects when resolving globally.) Since, there's currently no use for the global resolution, modify the existing function to take cgroup NS into account. Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces") Signed-off-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cgroup: cgroup_get_from_id() must check the looked-up kn is a directory

2022-09-28T09:32:22Z

commit df02452f3df069a59bc9e69c84435bf115cb6e37 upstream. cgroup has to be one kernfs dir, otherwise kernel panic is caused, especially cgroup id is provide from userspace. Reported-by: Marco Patalano Fixes: 6b658c4863c1 ("scsi: cgroup: Add cgroup_get_from_id()") Cc: Muneendra Signed-off-by: Ming Lei Acked-by: Mukesh Ojha Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock

2022-09-15T08:47:11Z

[ Upstream commit 4f7e7236435ca0abe005c674ebd6892c6e83aeb3 ] Bringing up a CPU may involve creating and destroying tasks which requires read-locking threadgroup_rwsem, so threadgroup_rwsem nests inside cpus_read_lock(). However, cpuset's ->attach(), which may be called with thredagroup_rwsem write-locked, also wants to disable CPU hotplug and acquires cpus_read_lock(), leading to a deadlock. Fix it by guaranteeing that ->attach() is always called with CPU hotplug disabled and removing cpus_read_lock() call from cpuset_attach(). Signed-off-by: Tejun Heo Reviewed-and-tested-by: Imran Khan Reported-and-tested-by: Xuewen Yan Fixes: 05c7b7a92cc8 ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug") Cc: stable@vger.kernel.org # v5.17+ Signed-off-by: Sasha Levin

cgroup: Elide write-locking threadgroup_rwsem when updating csses on an empty subtree

2022-09-15T08:47:11Z

[ Upstream commit 671c11f0619e5ccb380bcf0f062f69ba95fc974a ] cgroup_update_dfl_csses() write-lock the threadgroup_rwsem as updating the csses can trigger process migrations. However, if the subtree doesn't contain any tasks, there aren't gonna be any cgroup migrations. This condition can be trivially detected by testing whether mgctx.preloaded_src_csets is empty. Elide write-locking threadgroup_rwsem if the subtree is empty. After this optimization, the usage pattern of creating a cgroup, enabling the necessary controllers, and then seeding it with CLONE_INTO_CGROUP and then removing the cgroup after it becomes empty doesn't need to write-lock threadgroup_rwsem at all. Signed-off-by: Tejun Heo Cc: Christian Brauner Cc: Michal Koutný Signed-off-by: Sasha Levin

cgroup: Fix race condition at rebind_subsystems()

2022-08-31T15:17:59Z

commit 763f4fb76e24959c370cdaa889b2492ba6175580 upstream. Root cause: The rebind_subsystems() is no lock held when move css object from A list to B list,then let B's head be treated as css node at list_for_each_entry_rcu(). Solution: Add grace period before invalidating the removed rstat_css_node. Reported-by: Jing-Ting Wu Suggested-by: Michal Koutný Signed-off-by: Jing-Ting Wu Tested-by: Jing-Ting Wu Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/ Acked-by: Mukesh Ojha Fixes: a7df69b81aac ("cgroup: rstat: support cgroup1") Cc: stable@vger.kernel.org # v5.13+ Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

cgroup: Use separate src/dst nodes when preloading css_sets for migration

2022-06-16T19:37:02Z

Each cset (css_set) is pinned by its tasks. When we're moving tasks around across csets for a migration, we need to hold the source and destination csets to ensure that they don't go away while we're moving tasks about. This is done by linking cset->mg_preload_node on either the mgctx->preloaded_src_csets or mgctx->preloaded_dst_csets list. Using the same cset->mg_preload_node for both the src and dst lists was deemed okay as a cset can't be both the source and destination at the same time. Unfortunately, this overloading becomes problematic when multiple tasks are involved in a migration and some of them are identity noop migrations while others are actually moving across cgroups. For example, this can happen with the following sequence on cgroup1: #1> mkdir -p /sys/fs/cgroup/misc/a/b #2> echo $$ > /sys/fs/cgroup/misc/a/cgroup.procs #3> RUN_A_COMMAND_WHICH_CREATES_MULTIPLE_THREADS & #4> PID=$! #5> echo $PID > /sys/fs/cgroup/misc/a/b/tasks #6> echo $PID > /sys/fs/cgroup/misc/a/cgroup.procs the process including the group leader back into a. In this final migration, non-leader threads would be doing identity migration while the group leader is doing an actual one. After #3, let's say the whole process was in cset A, and that after #4, the leader moves to cset B. Then, during #6, the following happens: 1. cgroup_migrate_add_src() is called on B for the leader. 2. cgroup_migrate_add_src() is called on A for the other threads. 3. cgroup_migrate_prepare_dst() is called. It scans the src list. 4. It notices that B wants to migrate to A, so it tries to A to the dst list but realizes that its ->mg_preload_node is already busy. 5. and then it notices A wants to migrate to A as it's an identity migration, it culls it by list_del_init()'ing its ->mg_preload_node and putting references accordingly. 6. The rest of migration takes place with B on the src list but nothing on the dst list. This means that A isn't held while migration is in progress. If all tasks leave A before the migration finishes and the incoming task pins it, the cset will be destroyed leading to use-after-free. This is caused by overloading cset->mg_preload_node for both src and dst preload lists. We wanted to exclude the cset from the src list but ended up inadvertently excluding it from the dst list too. This patch fixes the issue by separating out cset->mg_preload_node into ->mg_src_preload_node and ->mg_dst_preload_node, so that the src and dst preloadings don't interfere with each other. Signed-off-by: Tejun Heo Reported-by: Mukesh Ojha Reported-by: shisiyuan Link: http://lkml.kernel.org/r/1654187688-27411-1-git-send-email-shisiyuan@xiaomi.com Link: https://www.spinics.net/lists/cgroups/msg33313.html Fixes: f817de98513d ("cgroup: prepare migration path for unified hierarchy") Cc: stable@vger.kernel.org # v3.16+

cgroup: remove the superfluous judgment

2022-05-20T07:49:45Z

Remove the superfluous judgment since the function is never called for a root cgroup, as suggested by Tejun. Suggested-by: Tejun Heo Signed-off-by: Shida Zhang Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo

cgroup: Make cgroup_debug static

2022-05-18T16:59:20Z

Make cgroup_debug static since it's only used in cgroup.c Signed-off-by: Xiu Jianfeng Signed-off-by: Tejun Heo

Merge tag 'driver-core-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2022-03-28T19:41:28Z

Pull driver core updates from Greg KH: "Here is the set of driver core changes for 5.18-rc1. Not much here, primarily it was a bunch of cleanups and small updates: - kobj_type cleanups for default_groups - documentation updates - firmware loader minor changes - component common helper added and take advantage of it in many drivers (the largest part of this pull request). All of these have been in linux-next for a while with no reported problems" * tag 'driver-core-5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (54 commits) Documentation: update stable review cycle documentation drivers/base/dd.c : Remove the initial value of the global variable Documentation: update stable tree link Documentation: add link to stable release candidate tree devres: fix typos in comments Documentation: add note block surrounding security patch note samples/kobject: Use sysfs_emit instead of sprintf base: soc: Make soc_device_match() simpler and easier to read driver core: dd: fix return value of __setup handler driver core: Refactor sysfs and drv/bus remove hooks driver core: Refactor multiple copies of device cleanup scripts: get_abi.pl: Fix typo in help message kernfs: fix typos in comments kernfs: remove unneeded #if 0 guard ALSA: hda/realtek: Make use of the helper component_compare_dev_name video: omapfb: dss: Make use of the helper component_compare_dev power: supply: ab8500: Make use of the helper component_compare_dev ASoC: codecs: wcd938x: Make use of the helper component_compare/release_of iommu/mediatek: Make use of the helper component_compare/release_of drm: of: Make use of the helper component_release_of ...

Merge branch 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2022-03-23T19:43:35Z

Pull cgroup updates from Tejun Heo: "All trivial cleanups without meaningful behavior changes" * 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: cleanup comments cgroup: Fix cgroup_can_fork() and cgroup_post_fork() kernel-doc comment cgroup: rstat: retrieve current bstat to delta directly cgroup: rstat: use same convention to assign cgroup_base_stat