Waiman Long 147f66d22f sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed ... [ Upstream commit b6e8d40d43 ] With cgroup v2, the cpuset's cpus_allowed mask can be empty indicating that the cpuset will just use the effective CPUs of its parent. So cpuset_can_attach() can call task_can_attach() with an empty mask. This can lead to cpumask_any_and() returns nr_cpu_ids causing the call to dl_bw_of() to crash due to percpu value access of an out of bound CPU value. For example: [80468.182258] BUG: unable to handle page fault for address: ffffffff8b6648b0 : [80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0 : [80468.207946] Call Trace: [80468.208947] cpuset_can_attach+0xa0/0x140 [80468.209953] cgroup_migrate_execute+0x8c/0x490 [80468.210931] cgroup_update_dfl_csses+0x254/0x270 [80468.211898] cgroup_subtree_control_write+0x322/0x400 [80468.212854] kernfs_fop_write_iter+0x11c/0x1b0 [80468.213777] new_sync_write+0x11f/0x1b0 [80468.214689] vfs_write+0x1eb/0x280 [80468.215592] ksys_write+0x5f/0xe0 [80468.216463] do_syscall_64+0x5c/0x80 [80468.224287] entry_SYSCALL_64_after_hwframe+0x44/0xae Fix that by using effective_cpus instead. For cgroup v1, effective_cpus is the same as cpus_allowed. For v2, effective_cpus is the real cpumask to be used by tasks within the cpuset anyway. Also update task_can_attach()'s 2nd argument name to cs_effective_cpus to reflect the change. In addition, a check is added to task_can_attach() to guard against the possibility that cpumask_any_and() may return a value >= nr_cpu_ids. Fixes: 7f51412a41 ("sched/deadline: Fix bandwidth check/update when migrating tasks between exclusive cpusets") Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Juri Lelli <juri.lelli@redhat.com> Link: https://lore.kernel.org/r/20220803015451.2219567-1-longman@redhat.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-08-17 14:24:14 +02:00
..
Makefile	cgroup: Add misc cgroup controller	2021-04-04 13:34:46 -04:00
cgroup-internal.h	cgroup: Use open-time cgroup namespace for process migration perm checks	2022-01-11 15:35:15 +01:00
cgroup-v1.c	cgroup-v1: Correct privileges check in release_agent writes	2022-03-02 11:47:47 +01:00
cgroup.c	cgroup: Use separate src/dst nodes when preloading css_sets for migration	2022-07-21 21:24:13 +02:00
cpuset.c	sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed	2022-08-17 14:24:14 +02:00
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
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: Fix rootcg cpu.stat guest double counting	2021-11-18 19:16:45 +01:00