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db6a5018b6
rcu_read_lock is needed to protect access to psock inside sock_map_unref
when tearing down the map. However, we can't afford to sleep in lock_sock
while in RCU read-side critical section. Grab the RCU lock only after we
have locked the socket.
This fixes RCU warnings triggerable on a VM with 1 vCPU when free'ing a
sockmap/sockhash that contains at least one socket:
| =============================
| WARNING: suspicious RCU usage
| 5.5.0-04005-g8fc91b972b73 #450 Not tainted
| -----------------------------
| include/linux/rcupdate.h:272 Illegal context switch in RCU read-side critical section!
|
| other info that might help us debug this:
|
|
| rcu_scheduler_active = 2, debug_locks = 1
| 4 locks held by kworker/0:1/62:
| #0: ffff88813b019748 ((wq_completion)events){+.+.}, at: process_one_work+0x1d7/0x5e0
| #1: ffffc900000abe50 ((work_completion)(&map->work)){+.+.}, at: process_one_work+0x1d7/0x5e0
| #2: ffffffff82065d20 (rcu_read_lock){....}, at: sock_map_free+0x5/0x170
| #3: ffff8881368c5df8 (&stab->lock){+...}, at: sock_map_free+0x64/0x170
|
| stack backtrace:
| CPU: 0 PID: 62 Comm: kworker/0:1 Not tainted 5.5.0-04005-g8fc91b972b73 #450
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
| Workqueue: events bpf_map_free_deferred
| Call Trace:
| dump_stack+0x71/0xa0
| ___might_sleep+0x105/0x190
| lock_sock_nested+0x28/0x90
| sock_map_free+0x95/0x170
| bpf_map_free_deferred+0x58/0x80
| process_one_work+0x260/0x5e0
| worker_thread+0x4d/0x3e0
| kthread+0x108/0x140
| ? process_one_work+0x5e0/0x5e0
| ? kthread_park+0x90/0x90
| ret_from_fork+0x3a/0x50
| =============================
| WARNING: suspicious RCU usage
| 5.5.0-04005-g8fc91b972b73-dirty #452 Not tainted
| -----------------------------
| include/linux/rcupdate.h:272 Illegal context switch in RCU read-side critical section!
|
| other info that might help us debug this:
|
|
| rcu_scheduler_active = 2, debug_locks = 1
| 4 locks held by kworker/0:1/62:
| #0: ffff88813b019748 ((wq_completion)events){+.+.}, at: process_one_work+0x1d7/0x5e0
| #1: ffffc900000abe50 ((work_completion)(&map->work)){+.+.}, at: process_one_work+0x1d7/0x5e0
| #2: ffffffff82065d20 (rcu_read_lock){....}, at: sock_hash_free+0x5/0x1d0
| #3: ffff888139966e00 (&htab->buckets[i].lock){+...}, at: sock_hash_free+0x92/0x1d0
|
| stack backtrace:
| CPU: 0 PID: 62 Comm: kworker/0:1 Not tainted 5.5.0-04005-g8fc91b972b73-dirty #452
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
| Workqueue: events bpf_map_free_deferred
| Call Trace:
| dump_stack+0x71/0xa0
| ___might_sleep+0x105/0x190
| lock_sock_nested+0x28/0x90
| sock_hash_free+0xec/0x1d0
| bpf_map_free_deferred+0x58/0x80
| process_one_work+0x260/0x5e0
| worker_thread+0x4d/0x3e0
| kthread+0x108/0x140
| ? process_one_work+0x5e0/0x5e0
| ? kthread_park+0x90/0x90
| ret_from_fork+0x3a/0x50
Fixes:
|
||
|---|---|---|
| .. | ||
| bpf_sk_storage.c | ||
| datagram.c | ||
| datagram.h | ||
| dev_addr_lists.c | ||
| dev_ioctl.c | ||
| dev.c | ||
| devlink.c | ||
| drop_monitor.c | ||
| dst_cache.c | ||
| dst.c | ||
| failover.c | ||
| fib_notifier.c | ||
| fib_rules.c | ||
| filter.c | ||
| flow_dissector.c | ||
| flow_offload.c | ||
| gen_estimator.c | ||
| gen_stats.c | ||
| gro_cells.c | ||
| hwbm.c | ||
| link_watch.c | ||
| lwt_bpf.c | ||
| lwtunnel.c | ||
| Makefile | ||
| neighbour.c | ||
| net_namespace.c | ||
| net-procfs.c | ||
| net-sysfs.c | ||
| net-sysfs.h | ||
| net-traces.c | ||
| netclassid_cgroup.c | ||
| netevent.c | ||
| netpoll.c | ||
| netprio_cgroup.c | ||
| page_pool.c | ||
| pktgen.c | ||
| ptp_classifier.c | ||
| request_sock.c | ||
| rtnetlink.c | ||
| scm.c | ||
| secure_seq.c | ||
| skbuff.c | ||
| skmsg.c | ||
| sock_diag.c | ||
| sock_map.c | ||
| sock_reuseport.c | ||
| sock.c | ||
| stream.c | ||
| sysctl_net_core.c | ||
| timestamping.c | ||
| tso.c | ||
| utils.c | ||
| xdp.c | ||