Quanyang Wang 04f8ef5643 cgroup: Fix memory leak caused by missing cgroup_bpf_offline ... When enabling CONFIG_CGROUP_BPF, kmemleak can be observed by running the command as below: $mount -t cgroup -o none,name=foo cgroup cgroup/ $umount cgroup/ unreferenced object 0xc3585c40 (size 64): comm "mount", pid 425, jiffies 4294959825 (age 31.990s) hex dump (first 32 bytes): 01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00 ......(......... 00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00 ........lC...... backtrace: [<e95a2f9e>] cgroup_bpf_inherit+0x44/0x24c [<1f03679c>] cgroup_setup_root+0x174/0x37c [<ed4b0ac5>] cgroup1_get_tree+0x2c0/0x4a0 [<f85b12fd>] vfs_get_tree+0x24/0x108 [<f55aec5c>] path_mount+0x384/0x988 [<e2d5e9cd>] do_mount+0x64/0x9c [<208c9cfe>] sys_mount+0xfc/0x1f4 [<06dd06e0>] ret_fast_syscall+0x0/0x48 [<a8308cb3>] 0xbeb4daa8 This is because that since the commit 2b0d3d3e4f ("percpu_ref: reduce memory footprint of percpu_ref in fast path") root_cgrp->bpf.refcnt.data is allocated by the function percpu_ref_init in cgroup_bpf_inherit which is called by cgroup_setup_root when mounting, but not freed along with root_cgrp when umounting. Adding cgroup_bpf_offline which calls percpu_ref_kill to cgroup_kill_sb can free root_cgrp->bpf.refcnt.data in umount path. This patch also fixes the commit 4bfc0bb2c6 ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself"). A cgroup_bpf_offline is needed to do a cleanup that frees the resources which are allocated by cgroup_bpf_inherit in cgroup_setup_root. And inside cgroup_bpf_offline, cgroup_get() is at the beginning and cgroup_put is at the end of cgroup_bpf_release which is called by cgroup_bpf_offline. So cgroup_bpf_offline can keep the balance of cgroup's refcount. Fixes: 2b0d3d3e4f ("percpu_ref: reduce memory footprint of percpu_ref in fast path") Fixes: 4bfc0bb2c6 ("bpf: decouple the lifetime of cgroup_bpf from cgroup itself") Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20211018075623.26884-1-quanyang.wang@windriver.com		2021-10-22 17:23:54 -07:00
..
cgroup-internal.h	fs_parse: fold fs_parameter_desc/fs_parameter_spec	2020-02-07 14:48:37 -05:00
cgroup-v1.c	Merge branch 'for-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2021-08-31 15:49:04 -07:00
cgroup.c	cgroup: Fix memory leak caused by missing cgroup_bpf_offline	2021-10-22 17:23:54 -07:00
cpuset.c	cgroup/cpuset: Change references of cpuset_mutex to cpuset_rwsem	2021-09-13 08:06:17 -10:00
debug.c	kernel: cgroup: fix misuse of %x	2019-05-06 08:47:48 -07:00
freezer.c	cgroup: freezer: don't change task and cgroups status unnecessarily	2019-11-07 07:38:41 -08:00
legacy_freezer.c	cgroup: rename freezer.c into legacy_freezer.c	2019-04-19 11:26:48 -07:00
Makefile	cgroup: Add misc cgroup controller	2021-04-04 13:34:46 -04:00
misc.c	svm/sev: Register SEV and SEV-ES ASIDs to the misc controller	2021-04-04 13:34:46 -04:00
namespace.c	memcg: enable accounting for new namesapces and struct nsproxy	2021-09-03 09:58:12 -07:00
pids.c	clone3: allow spawning processes into cgroups	2020-02-12 17:57:51 -05:00
rdma.c	cgroup: fix spelling mistakes	2021-05-24 12:45:26 -04:00
rstat.c	cgroup: rstat: fix A-A deadlock on 32bit around u64_stats_sync	2021-07-27 13:12:20 -10:00