=============================
WARNING: suspicious RCU usage
5.12.0-rc4-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8294 Illegal context switch in RCU-bh read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
4 locks held by kworker/0:4/4925:
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
 #1: ffffc900016afda8 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
 #2: ffffffff8d66d328 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4572
 #3: ffffffff8bf74300 (rcu_read_lock_bh){....}-{1:2}, at: addrconf_verify_rtnl+0x2b/0x1150 net/ipv6/addrconf.c:4459

stack backtrace:
CPU: 0 PID: 4925 Comm: kworker/0:4 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep+0x229/0x2c0 kernel/sched/core.c:8294
 __mutex_lock_common kernel/locking/mutex.c:928 [inline]
 __mutex_lock+0xa9/0x1120 kernel/locking/mutex.c:1096
 __ipv6_dev_mc_dec+0x5f/0x340 net/ipv6/mcast.c:970
 addrconf_leave_solict net/ipv6/addrconf.c:2182 [inline]
 addrconf_leave_solict net/ipv6/addrconf.c:2174 [inline]
 __ipv6_ifa_notify+0x5b6/0xa90 net/ipv6/addrconf.c:6077
 ipv6_ifa_notify net/ipv6/addrconf.c:6100 [inline]
 ipv6_del_addr+0x463/0xae0 net/ipv6/addrconf.c:1294
 addrconf_verify_rtnl+0xd59/0x1150 net/ipv6/addrconf.c:4488
 addrconf_verify_work+0xf/0x20 net/ipv6/addrconf.c:4573
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:928
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4925, name: kworker/0:4
4 locks held by kworker/0:4/4925:
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
 #1: ffffc900016afda8 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
 #2: ffffffff8d66d328 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4572
 #3: ffffffff8bf74300 (rcu_read_lock_bh){....}-{1:2}, at: addrconf_verify_rtnl+0x2b/0x1150 net/ipv6/addrconf.c:4459
Preemption disabled at:
[<ffffffff87b39f41>] local_bh_disable include/linux/bottom_half.h:19 [inline]
[<ffffffff87b39f41>] rcu_read_lock_bh include/linux/rcupdate.h:727 [inline]
[<ffffffff87b39f41>] addrconf_verify_rtnl+0x41/0x1150 net/ipv6/addrconf.c:4461
CPU: 0 PID: 4925 Comm: kworker/0:4 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:8328
 __mutex_lock_common kernel/locking/mutex.c:928 [inline]
 __mutex_lock+0xa9/0x1120 kernel/locking/mutex.c:1096
 __ipv6_dev_mc_dec+0x5f/0x340 net/ipv6/mcast.c:970
 addrconf_leave_solict net/ipv6/addrconf.c:2182 [inline]
 addrconf_leave_solict net/ipv6/addrconf.c:2174 [inline]
 __ipv6_ifa_notify+0x5b6/0xa90 net/ipv6/addrconf.c:6077
 ipv6_ifa_notify net/ipv6/addrconf.c:6100 [inline]
 ipv6_del_addr+0x463/0xae0 net/ipv6/addrconf.c:1294
 addrconf_verify_rtnl+0xd59/0x1150 net/ipv6/addrconf.c:4488
 addrconf_verify_work+0xf/0x20 net/ipv6/addrconf.c:4573
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

=============================
[ BUG: Invalid wait context ]
5.12.0-rc4-syzkaller #0 Tainted: G        W        
-----------------------------
kworker/0:4/4925 is trying to lock:
ffff88801aeef530 (&idev->mc_lock){+.+.}-{3:3}, at: __ipv6_dev_mc_dec+0x5f/0x340 net/ipv6/mcast.c:970
other info that might help us debug this:
context-{4:4}
4 locks held by kworker/0:4/4925:
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8880211d7d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
 #1: ffffc900016afda8 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250
 #2: ffffffff8d66d328 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4572
 #3: ffffffff8bf74300 (rcu_read_lock_bh){....}-{1:2}, at: addrconf_verify_rtnl+0x2b/0x1150 net/ipv6/addrconf.c:4459
stack backtrace:
CPU: 0 PID: 4925 Comm: kworker/0:4 Tainted: G        W         5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_lock_invalid_wait_context kernel/locking/lockdep.c:4551 [inline]
 check_wait_context kernel/locking/lockdep.c:4612 [inline]
 __lock_acquire.cold+0x219/0x3b4 kernel/locking/lockdep.c:4850
 lock_acquire kernel/locking/lockdep.c:5510 [inline]
 lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475
 __mutex_lock_common kernel/locking/mutex.c:949 [inline]
 __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096
 __ipv6_dev_mc_dec+0x5f/0x340 net/ipv6/mcast.c:970
 addrconf_leave_solict net/ipv6/addrconf.c:2182 [inline]
 addrconf_leave_solict net/ipv6/addrconf.c:2174 [inline]
 __ipv6_ifa_notify+0x5b6/0xa90 net/ipv6/addrconf.c:6077
 ipv6_ifa_notify net/ipv6/addrconf.c:6100 [inline]
 ipv6_del_addr+0x463/0xae0 net/ipv6/addrconf.c:1294
 addrconf_verify_rtnl+0xd59/0x1150 net/ipv6/addrconf.c:4488
 addrconf_verify_work+0xf/0x20 net/ipv6/addrconf.c:4573
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294