lwn.git/kernel/cgroup/cgroup-v1.c, branch v6.9

Merge tag 'driver-core-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2024-01-18T17:48:40+00:00

Pull driver core updates from Greg KH: "Here are the set of driver core and kernfs changes for 6.8-rc1. Nothing major in here this release cycle, just lots of small cleanups and some tweaks on kernfs that in the very end, got reverted and will come back in a safer way next release cycle. Included in here are: - more driver core 'const' cleanups and fixes - fw_devlink=rpm is now the default behavior - kernfs tiny changes to remove some string functions - cpu handling in the driver core is updated to work better on many systems that add topologies and cpus after booting - other minor changes and cleanups All of the cpu handling patches have been acked by the respective maintainers and are coming in here in one series. Everything has been in linux-next for a while with no reported issues" * tag 'driver-core-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (51 commits) Revert "kernfs: convert kernfs_idr_lock to an irq safe raw spinlock" kernfs: convert kernfs_idr_lock to an irq safe raw spinlock class: fix use-after-free in class_register() PM: clk: make pm_clk_add_notifier() take a const pointer EDAC: constantify the struct bus_type usage kernfs: fix reference to renamed function driver core: device.h: fix Excess kernel-doc description warning driver core: class: fix Excess kernel-doc description warning driver core: mark remaining local bus_type variables as const driver core: container: make container_subsys const driver core: bus: constantify subsys_register() calls driver core: bus: make bus_sort_breadthfirst() take a const pointer kernfs: d_obtain_alias(NULL) will do the right thing... driver core: Better advertise dev_err_probe() kernfs: Convert kernfs_path_from_node_locked() from strlcpy() to strscpy() kernfs: Convert kernfs_name_locked() from strlcpy() to strscpy() kernfs: Convert kernfs_walk_ns() from strlcpy() to strscpy() initramfs: Expose retained initrd as sysfs file fs/kernfs/dir: obey S_ISGID kernel/cgroup: use kernfs_create_dir_ns() ...

kernfs: Convert kernfs_path_from_node_locked() from strlcpy() to strscpy()

2023-12-15T16:25:10+00:00

One of the last remaining users of strlcpy() in the kernel is kernfs_path_from_node_locked(), which passes back the problematic "length we _would_ have copied" return value to indicate truncation. Convert the chain of all callers to use the negative return value (some of which already doing this explicitly). All callers were already also checking for negative return values, so the risk to missed checks looks very low. In this analysis, it was found that cgroup1_release_agent() actually didn't handle the "too large" condition, so this is technically also a bug fix. :) Here's the chain of callers, and resolution identifying each one as now handling the correct return value: kernfs_path_from_node_locked() kernfs_path_from_node() pr_cont_kernfs_path() returns void kernfs_path() sysfs_warn_dup() return value ignored cgroup_path() blkg_path() bfq_bic_update_cgroup() return value ignored TRACE_IOCG_PATH() return value ignored TRACE_CGROUP_PATH() return value ignored perf_event_cgroup() return value ignored task_group_path() return value ignored damon_sysfs_memcg_path_eq() return value ignored get_mm_memcg_path() return value ignored lru_gen_seq_show() return value ignored cgroup_path_from_kernfs_id() return value ignored cgroup_show_path() already converted "too large" error to negative value cgroup_path_ns_locked() cgroup_path_ns() bpf_iter_cgroup_show_fdinfo() return value ignored cgroup1_release_agent() wasn't checking "too large" error proc_cgroup_show() already converted "too large" to negative value Cc: Greg Kroah-Hartman Cc: Tejun Heo Cc: Zefan Li Cc: Johannes Weiner Cc: Waiman Long Cc: Co-developed-by: Azeem Shaikh Signed-off-by: Azeem Shaikh Link: https://lore.kernel.org/r/20231116192127.1558276-3-keescook@chromium.org Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20231212211741.164376-3-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman

cgroup: Add a new helper for cgroup1 hierarchy

2023-11-09T23:25:47+00:00

A new helper is added for cgroup1 hierarchy: - task_get_cgroup1 Acquires the associated cgroup of a task within a specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its hierarchy ID. This helper function is added to facilitate the tracing of tasks within a particular container or cgroup dir in BPF programs. It's important to note that this helper is designed specifically for cgroup1 only. tj: Use irsqsave/restore as suggested by Hou Tao . Suggested-by: Tejun Heo Signed-off-by: Yafang Shao Cc: Hou Tao Signed-off-by: Tejun Heo

cgroup: Remove duplicates in cgroup v1 tasks file

2023-10-09T16:42:05+00:00

One PID may appear multiple times in a preloaded pidlist. (Possibly due to PID recycling but we have reports of the same task_struct appearing with different PIDs, thus possibly involving transfer of PID via de_thread().) Because v1 seq_file iterator uses PIDs as position, it leads to a message: > seq_file: buggy .next function kernfs_seq_next did not update position index Conservative and quick fix consists of removing duplicates from `tasks` file (as opposed to removing pidlists altogether). It doesn't affect correctness (it's sufficient to show a PID once), performance impact would be hidden by unconditional sorting of the pidlist already in place (asymptotically). Link: https://lore.kernel.org/r/20230823174804.23632-1-mkoutny@suse.com/ Suggested-by: Firo Yang Signed-off-by: Michal Koutný Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org

cgroup: clean up if condition in cgroup_pidlist_start()

2023-08-07T18:30:06+00:00

There's no need to use '<=' when knowing 'l->list[mid] != pid' already. No functional change intended. Signed-off-by: Miaohe Lin Signed-off-by: Tejun Heo

Merge tag 'cgroup-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2023-06-27T23:54:21+00:00

Pull cgroup updates from Tejun Heo: - Whenever cpuset needs to rebuild sched_domain, it walked all tasks looking for DEADLINE tasks as they need to be accounted on the new domain. Walking all tasks can be expensive and there may not be any DEADLINE tasks at all. Task iteration is now omitted if there are no DEADLINE tasks - Fixes DEADLINE bandwidth misaccounting after task migration failures - When no controller is enabled, -Wstringop-overflow warning is triggered. The fix patch added an early exit which is too eager and got reverted for now. Will fix later - Everything else is minor cleanups * tag 'cgroup-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: Revert "cgroup: Avoid -Wstringop-overflow warnings" cgroup/misc: Expose misc.current on cgroup v2 root cgroup: Avoid -Wstringop-overflow warnings cgroup: remove obsolete comment on cgroup_on_dfl() cgroup: remove unused task_cgroup_path() cgroup/cpuset: remove unneeded header files cgroup: make cgroup_is_threaded() and cgroup_is_thread_root() static rdmacg: fix kernel-doc warnings in rdmacg cgroup: Replace the css_set call with cgroup_get cgroup: remove unused macro for_each_e_css() cgroup: Update out-of-date comment in cgroup_migrate() cgroup: Replace all non-returning strlcpy with strscpy cgroup/cpuset: remove unneeded header files cgroup/cpuset: Free DL BW in case can_attach() fails sched/deadline: Create DL BW alloc, free & check overflow interface cgroup/cpuset: Iterate only if DEADLINE tasks are present sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets sched/cpuset: Bring back cpuset_mutex cgroup/cpuset: Rename functions dealing with DEADLINE accounting

cgroup: Replace all non-returning strlcpy with strscpy

2023-05-22T19:05:57+00:00

strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated [1]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). No return values were used, so direct replacement is safe. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh Reviewed-by: Kees Cook Signed-off-by: Tejun Heo

cgroup: fix missing cpus_read_{lock,unlock}() in cgroup_transfer_tasks()

2023-05-22T18:42:14+00:00

The commit 4f7e7236435c ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") fixed the deadlock between cgroup_threadgroup_rwsem and cpus_read_lock() by introducing cgroup_attach_{lock,unlock}() and removing cpus_read_{lock,unlock}() from cpuset_attach(). But cgroup_transfer_tasks() was missed and not handled, which will cause th following warning: WARNING: CPU: 0 PID: 589 at kernel/cpu.c:526 lockdep_assert_cpus_held+0x32/0x40 CPU: 0 PID: 589 Comm: kworker/1:4 Not tainted 6.4.0-rc2-next-20230517 #50 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 Workqueue: events cpuset_hotplug_workfn RIP: 0010:lockdep_assert_cpus_held+0x32/0x40 <...> Call Trace: cpuset_attach+0x40/0x240 cgroup_migrate_execute+0x452/0x5e0 ? _raw_spin_unlock_irq+0x28/0x40 cgroup_transfer_tasks+0x1f3/0x360 ? find_held_lock+0x32/0x90 ? cpuset_hotplug_workfn+0xc81/0xed0 cpuset_hotplug_workfn+0xcb1/0xed0 ? process_one_work+0x248/0x5b0 process_one_work+0x2b9/0x5b0 worker_thread+0x56/0x3b0 ? process_one_work+0x5b0/0x5b0 kthread+0xf1/0x120 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 So just use the cgroup_attach_{lock,unlock}() helper to fix it. Reported-by: Zhao Gongyi Signed-off-by: Qi Zheng Acked-by: Muchun Song Fixes: 05c7b7a92cc8 ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug") Cc: stable@vger.kernel.org # v5.17+ Signed-off-by: Tejun Heo

cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers

2023-03-17T22:07:13+00:00

Replace mutex_[un]lock() with cgroup_[un]lock() wrappers to stay consistent across cgroup core and other subsystem code, while operating on the cgroup_mutex. Signed-off-by: Kamalesh Babulal Acked-by: Alexei Starovoitov Reviewed-by: Christian Brauner Signed-off-by: Tejun Heo

cgroup: Use cgroup_attach_{lock,unlock}() from cgroup_attach_task_all()

2022-08-26T21:14:34+00:00

No behavior changes; preparing for potential locking changes in future. Signed-off-by: Tetsuo Handa Reviewed-by:Mukesh Ojha Signed-off-by: Tejun Heo