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| author | Waiman Long <longman@redhat.com> | 2022-08-03 03:54:51 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2022-08-03 10:34:26 +0200 |
| commit | b6e8d40d43ae4dec00c8fea2593eeea3114b8f44 (patch) | |
| tree | 511841983752ea4c2039ba7e033e5f678d55bcae /kernel/cgroup | |
| parent | Merge tag 'irq-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/... (diff) | |
| download | linux-b6e8d40d43ae4dec00c8fea2593eeea3114b8f44.tar.xz linux-b6e8d40d43ae4dec00c8fea2593eeea3114b8f44.zip | |
sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed
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: 7f51412a415d ("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
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/cpuset.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 71a418858a5e..58aadfda9b8b 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2239,7 +2239,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) goto out_unlock; cgroup_taskset_for_each(task, css, tset) { - ret = task_can_attach(task, cs->cpus_allowed); + ret = task_can_attach(task, cs->effective_cpus); if (ret) goto out_unlock; ret = security_task_setscheduler(task); |