On Thu, May 23, 2019 at 12:45:28PM -0700, Roman Gushchin wrote: > This patchset implements a cgroup bpf auto-detachment functionality: > bpf programs are detached as soon as possible after removal of the > cgroup, without waiting for the release of all associated resources. The idea looks great, but doesn't quite work: $ ./test_cgroup_attach #override:PASS [ 66.475219] BUG: sleeping function called from invalid context at ../include/linux/percpu-rwsem.h:34 [ 66.476095] in_atomic(): 1, irqs_disabled(): 0, pid: 21, name: ksoftirqd/2 [ 66.476706] CPU: 2 PID: 21 Comm: ksoftirqd/2 Not tainted 5.2.0-rc1-00211-g1861420d0162 #1564 [ 66.477595] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 [ 66.478360] Call Trace: [ 66.478591] dump_stack+0x5b/0x8b [ 66.478892] ___might_sleep+0x22f/0x290 [ 66.479230] cpus_read_lock+0x18/0x50 [ 66.479550] static_key_slow_dec+0x41/0x70 [ 66.479914] cgroup_bpf_release+0x1a6/0x400 [ 66.480285] percpu_ref_switch_to_atomic_rcu+0x203/0x330 [ 66.480754] rcu_core+0x475/0xcc0 [ 66.481047] ? switch_mm_irqs_off+0x684/0xa40 [ 66.481422] ? rcu_note_context_switch+0x260/0x260 [ 66.481842] __do_softirq+0x1cf/0x5ff [ 66.482174] ? takeover_tasklets+0x5f0/0x5f0 [ 66.482542] ? smpboot_thread_fn+0xab/0x780 [ 66.482911] run_ksoftirqd+0x1a/0x40 [ 66.483225] smpboot_thread_fn+0x3ad/0x780 [ 66.483583] ? sort_range+0x20/0x20 [ 66.483894] ? __kthread_parkme+0xb0/0x190 [ 66.484253] ? sort_range+0x20/0x20 [ 66.484562] ? sort_range+0x20/0x20 [ 66.484878] kthread+0x2e2/0x3e0 [ 66.485166] ? kthread_create_worker_on_cpu+0xb0/0xb0 [ 66.485620] ret_from_fork+0x1f/0x30 Same test runs fine before the patches.
