linux/kernel
Hao Luo d4ccaf58a8 bpf: Introduce cgroup iter
Cgroup_iter is a type of bpf_iter. It walks over cgroups in four modes:

 - walking a cgroup's descendants in pre-order.
 - walking a cgroup's descendants in post-order.
 - walking a cgroup's ancestors.
 - process only the given cgroup.

When attaching cgroup_iter, one can set a cgroup to the iter_link
created from attaching. This cgroup is passed as a file descriptor
or cgroup id and serves as the starting point of the walk. If no
cgroup is specified, the starting point will be the root cgroup v2.

For walking descendants, one can specify the order: either pre-order or
post-order. For walking ancestors, the walk starts at the specified
cgroup and ends at the root.

One can also terminate the walk early by returning 1 from the iter
program.

Note that because walking cgroup hierarchy holds cgroup_mutex, the iter
program is called with cgroup_mutex held.

Currently only one session is supported, which means, depending on the
volume of data bpf program intends to send to user space, the number
of cgroups that can be walked is limited. For example, given the current
buffer size is 8 * PAGE_SIZE, if the program sends 64B data for each
cgroup, assuming PAGE_SIZE is 4kb, the total number of cgroups that can
be walked is 512. This is a limitation of cgroup_iter. If the output
data is larger than the kernel buffer size, after all data in the
kernel buffer is consumed by user space, the subsequent read() syscall
will signal EOPNOTSUPP. In order to work around, the user may have to
update their program to reduce the volume of data sent to output. For
example, skip some uninteresting cgroups. In future, we may extend
bpf_iter flags to allow customizing buffer size.

Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220824233117.1312810-2-haoluo@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-08-25 11:35:37 -07:00
..
bpf bpf: Introduce cgroup iter 2022-08-25 11:35:37 -07:00
cgroup Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-08-17 20:29:36 -07:00
configs Char / Misc driver changes for 6.0-rc1 2022-08-04 11:05:48 -07:00
debug Modules updates for v5.19-rc1 2022-05-26 17:13:43 -07:00
dma remoteproc updates for v5.20 2022-08-08 15:16:29 -07:00
entry context_tracking: Take NMI eqs entrypoints over RCU 2022-07-05 13:32:59 -07:00
events Misc fixes to kprobes and the faddr2line script, plus a cleanup. 2022-08-06 17:28:12 -07:00
futex drm for 5.19-rc1 2022-05-25 16:18:27 -07:00
gcov gcov: Remove compiler version check 2021-12-02 17:25:21 +09:00
irq irqchip/genirq updates for 5.20: 2022-07-28 12:36:35 +02:00
kcsan kcsan: test: Add a .kunitconfig to run KCSAN tests 2022-07-22 09:22:59 -06:00
livepatch Livepatching changes for 5.19 2022-06-02 08:55:01 -07:00
locking RCU pull request for v5.20 (or whatever) 2022-08-02 19:12:45 -07:00
module Modules updates for 6.0 2022-08-08 14:12:19 -07:00
power Char / Misc driver changes for 6.0-rc1 2022-08-04 11:05:48 -07:00
printk printk: do not wait for consoles when suspended 2022-07-15 10:52:11 +02:00
rcu - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
sched Various fixes: a deadline scheduler fix, a migration fix, a Sparse fix and a comment fix. 2022-08-06 17:34:06 -07:00
time Networking changes for 6.0. 2022-08-03 16:29:08 -07:00
trace Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
.gitignore
acct.c kernel/acct: move acct sysctls to its own file 2022-04-06 13:43:44 -07:00
async.c Revert "module, async: async_synchronize_full() on module init iff async is used" 2022-02-03 11:20:34 -08:00
audit_fsnotify.c fsnotify: make allow_dups a property of the group 2022-04-25 14:37:18 +02:00
audit_tree.c audit: use fsnotify group lock helpers 2022-04-25 14:37:28 +02:00
audit_watch.c fsnotify: pass flags argument to fsnotify_alloc_group() 2022-04-25 14:37:12 +02:00
audit.c audit: make is_audit_feature_set() static 2022-06-13 14:08:57 -04:00
audit.h audit: log AUDIT_TIME_* records only from rules 2022-02-22 13:51:40 -05:00
auditfilter.c audit/stable-5.17 PR 20220110 2022-01-11 13:08:21 -08:00
auditsc.c audit: free module name 2022-06-15 19:28:44 -04:00
backtracetest.c
bounds.c
capability.c xfs: don't generate selinux audit messages for capability testing 2022-03-09 10:32:06 -08:00
cfi.c context_tracking: Take IRQ eqs entrypoints over RCU 2022-07-05 13:32:59 -07:00
compat.c arch: remove compat_alloc_user_space 2021-09-08 15:32:35 -07:00
configs.c
context_tracking.c MAINTAINERS: Add Paul as context tracking maintainer 2022-07-05 13:33:00 -07:00
cpu_pm.c context_tracking: Take IRQ eqs entrypoints over RCU 2022-07-05 13:32:59 -07:00
cpu.c Intel Trust Domain Extensions 2022-05-23 17:51:12 -07:00
crash_core.c kdump: round up the total memory size to 128M for crashkernel reservation 2022-07-17 17:31:40 -07:00
crash_dump.c
cred.c x86: Mark __invalid_creds() __noreturn 2022-03-15 10:32:44 +01:00
delayacct.c delayacct: track delays from write-protect copy 2022-06-01 15:55:25 -07:00
dma.c
exec_domain.c
exit.c exit: Fix typo in comment: s/sub-theads/sub-threads 2022-08-03 10:44:54 +02:00
extable.c context_tracking: Take NMI eqs entrypoints over RCU 2022-07-05 13:32:59 -07:00
fail_function.c
fork.c Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
freezer.c
gen_kheaders.sh kheaders: Have cpio unconditionally replace files 2022-05-08 03:16:59 +09:00
groups.c security: Add LSM hook to setgroups() syscall 2022-07-15 18:21:49 +00:00
hung_task.c kernel/hung_task: fix address space of proc_dohung_task_timeout_secs 2022-07-29 18:12:35 -07:00
iomem.c
irq_work.c irq_work: use kasan_record_aux_stack_noalloc() record callstack 2022-04-15 14:49:55 -07:00
jump_label.c jump_label: make initial NOP patching the special case 2022-06-24 09:48:55 +02:00
kallsyms_internal.h kallsyms: move declarations to internal header 2022-07-17 17:31:39 -07:00
kallsyms.c Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels" 2022-03-31 10:36:55 +02:00
kcov.c kcov: update pos before writing pc in trace function 2022-05-25 13:05:42 -07:00
kexec_core.c kexec: drop weak attribute from functions 2022-07-15 12:21:16 -04:00
kexec_elf.c
kexec_file.c Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kexec_internal.h
kexec.c kexec: avoid compat_alloc_user_space 2021-09-08 15:32:34 -07:00
kheaders.c
kmod.c
kprobes.c kprobes: Forbid probing on trampoline and BPF code areas 2022-08-02 11:47:29 +02:00
ksysfs.c kernel/ksysfs.c: use helper macro __ATTR_RW 2022-03-23 19:00:33 -07:00
kthread.c kthread: make it clear that kthread_create_on_node() might be terminated by any fatal signal 2022-06-16 19:11:30 -07:00
latencytop.c latencytop: move sysctl to its own file 2022-04-21 11:40:59 -07:00
Makefile kernel: remove platform_has() infrastructure 2022-08-01 07:42:56 +02:00
module_signature.c
notifier.c notifier: Add blocking/atomic_notifier_chain_register_unique_prio() 2022-05-19 19:30:30 +02:00
nsproxy.c fs/exec: allow to unshare a time namespace on vfork+exec 2022-06-15 07:58:04 -07:00
padata.c padata: replace cpumask_weight with cpumask_empty in padata.c 2022-01-31 11:21:46 +11:00
panic.c linux-kselftest-kunit-5.20-rc1 2022-08-02 19:34:45 -07:00
params.c kobject: remove kset from struct kset_uevent_ops callbacks 2021-12-28 11:26:18 +01:00
pid_namespace.c kernel: pid_namespace: use NULL instead of using plain integer as pointer 2022-04-29 14:38:00 -07:00
pid.c pid: add pidfd_get_task() helper 2021-10-14 13:29:18 +02:00
profile.c profile: setup_profiling_timer() is moslty not implemented 2022-07-29 18:12:36 -07:00
ptrace.c ptrace: fix clearing of JOBCTL_TRACED in ptrace_unfreeze_traced() 2022-07-09 11:06:19 -07:00
range.c
reboot.c Merge branch 'rework/kthreads' into for-linus 2022-06-23 19:11:28 +02:00
regset.c
relay.c relay: remove redundant assignment to pointer buf 2022-05-12 20:38:37 -07:00
resource_kunit.c
resource.c resource: Introduce alloc_free_mem_region() 2022-07-21 17:19:25 -07:00
rseq.c rseq: Kill process when unknown flags are encountered in ABI structures 2022-08-01 15:21:42 +02:00
scftorture.c scftorture: Fix distribution of short handler delays 2022-04-11 17:07:29 -07:00
scs.c kasan, vmalloc: only tag normal vmalloc allocations 2022-03-24 19:06:48 -07:00
seccomp.c seccomp: Add wait_killable semantic to seccomp user notifier 2022-05-03 14:11:58 -07:00
signal.c signal handling: don't use BUG_ON() for debugging 2022-07-07 09:53:43 -07:00
smp.c locking/csd_lock: Change csdlock_debug from early_param to __setup 2022-07-19 11:40:00 -07:00
smpboot.c cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again. 2022-04-12 14:13:01 +02:00
smpboot.h
softirq.c context_tracking: Take IRQ eqs entrypoints over RCU 2022-07-05 13:32:59 -07:00
stackleak.c stackleak: add on/off stack variants 2022-05-08 01:33:09 -07:00
stacktrace.c uaccess: remove CONFIG_SET_FS 2022-02-25 09:36:06 +01:00
static_call_inline.c static_call: Don't make __static_call_return0 static 2022-04-05 09:59:38 +02:00
static_call.c static_call: Don't make __static_call_return0 static 2022-04-05 09:59:38 +02:00
stop_machine.c Scheduler changes in this cycle were: 2022-05-24 11:11:13 -07:00
sys_ni.c mm/mempolicy: wire up syscall set_mempolicy_home_node 2022-01-15 16:30:30 +02:00
sys.c arm64/sme: Implement vector length configuration prctl()s 2022-04-22 18:50:54 +01:00
sysctl-test.c
sysctl.c kernel/sysctl.c: Remove trailing white space 2022-08-08 09:01:36 -07:00
task_work.c task_work: allow TWA_SIGNAL without a rescheduling IPI 2022-04-30 08:39:32 -06:00
taskstats.c kernel: make taskstats available from all net namespaces 2022-04-29 14:38:03 -07:00
torture.c torture: Wake up kthreads after storing task_struct pointer 2022-02-01 17:24:39 -08:00
tracepoint.c
tsacct.c taskstats: version 12 with thread group and exe info 2022-04-29 14:38:03 -07:00
ucount.c ucounts: Handle wrapping in is_ucounts_overlimit 2022-02-17 09:11:57 -06:00
uid16.c
uid16.h
umh.c kthread: Don't allocate kthread_struct for init and umh 2022-05-06 14:49:44 -05:00
up.c
user_namespace.c ucounts: Fix systemd LimitNPROC with private users regression 2022-02-25 10:40:14 -06:00
user-return-notifier.c
user.c fs/epoll: use a per-cpu counter for user's watches count 2021-09-08 11:50:27 -07:00
usermode_driver.c blob_to_mnt(): kern_unmount() is needed to undo kern_mount() 2022-05-19 23:25:47 -04:00
utsname_sysctl.c
utsname.c
watch_queue.c This was a moderately busy cycle for documentation, but nothing all that 2022-08-02 19:24:24 -07:00
watchdog_hld.c Revert "printk: add functions to prefer direct printing" 2022-06-23 18:41:40 +02:00
watchdog.c powerpc updates for 6.0 2022-08-06 16:38:17 -07:00
workqueue_internal.h workqueue: Assign a color to barrier work items 2021-08-17 07:49:10 -10:00
workqueue.c drm for 5.20/6.0 2022-08-03 19:52:08 -07:00