Re: [syzbot ci] Re: net/sched: act_api: use RCU with deferred freeing for action lifecycle

[Jamal Hadi Salim]

On Sat, May 30, 2026 at 4:00 PM syzbot ci
<syzbot+ci159f8dfc2e750c24@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> syzbot ci has tested the following series
>
> [v1] net/sched: act_api: use RCU with deferred freeing for action lifecycle
> https://lore.kernel.org/all/20260530115511.1352487-1-jhs@xxxxxxxxxxxx
> * [PATCH net 1/1] net/sched: act_api: use RCU with deferred freeing for action lifecycle
>
> and found the following issues:
> * BUG: sleeping function called from invalid context in __tcf_chain_put
> * inconsistent lock state in tcf_mirred_release
>
> Full report is available here:
> https://ci.syzbot.org/series/526aa788-9a02-4038-b101-5daf4d3436a2
>

Thanks for finding this. Will send a v2 with a fix.

cheers,
jamal

> ***
>
> BUG: sleeping function called from invalid context in __tcf_chain_put
>
> tree:      net
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net.git
> base:      78ef59e7a6459b16f8102e0ee1c718443323d1af
> arch:      amd64
> compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:    https://ci.syzbot.org/builds/46884a04-6831-455e-8868-d463d6e018db/config
> syz repro: https://ci.syzbot.org/findings/3fb6310c-78f8-44da-bd19-4acd582420fa/syz_repro
>
> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 23, name: ksoftirqd/1
> preempt_count: 100, expected: 0
> RCU nest depth: 0, expected: 0
> 1 lock held by ksoftirqd/1/23:
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_do_batch kernel/rcu/tree.c:2611 [inline]
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_core+0x751/0x1070 kernel/rcu/tree.c:2869
> Preemption disabled at:
> [<ffffffff8187d090>] softirq_handle_begin kernel/softirq.c:463 [inline]
> [<ffffffff8187d090>] handle_softirqs+0xb0/0x840 kernel/softirq.c:598
> CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  __might_resched+0x378/0x4d0 kernel/sched/core.c:9163
>  __mutex_lock_common kernel/locking/mutex.c:623 [inline]
>  __mutex_lock+0x11c/0x1550 kernel/locking/mutex.c:820
>  __tcf_chain_put+0x60/0x820 net/sched/cls_api.c:694
>  free_tcf net/sched/act_api.c:130 [inline]
>  tcf_action_cleanup net/sched/act_api.c:370 [inline]
>  tcf_action_rcu_free+0x39d/0x440 net/sched/act_api.c:378
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
>
> =============================
> [ BUG: Invalid wait context ]
> syzkaller #0 Tainted: G        W
> -----------------------------
> ksoftirqd/1/23 is trying to lock:
> ffff888171e3b0b0 (&block->lock){+.+.}-{4:4}, at: __tcf_chain_put+0x60/0x820 net/sched/cls_api.c:694
> other info that might help us debug this:
> context-{3:3}
> 1 lock held by ksoftirqd/1/23:
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_do_batch kernel/rcu/tree.c:2611 [inline]
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_core+0x751/0x1070 kernel/rcu/tree.c:2869
> stack backtrace:
> CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Tainted: G        W           syzkaller #0 PREEMPT(full)
> Tainted: [W]=WARN
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_lock_invalid_wait_context kernel/locking/lockdep.c:4830 [inline]
>  check_wait_context kernel/locking/lockdep.c:4902 [inline]
>  __lock_acquire+0xec1/0x2cf0 kernel/locking/lockdep.c:5187
>  lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
>  __mutex_lock_common kernel/locking/mutex.c:646 [inline]
>  __mutex_lock+0x1a3/0x1550 kernel/locking/mutex.c:820
>  __tcf_chain_put+0x60/0x820 net/sched/cls_api.c:694
>  free_tcf net/sched/act_api.c:130 [inline]
>  tcf_action_cleanup net/sched/act_api.c:370 [inline]
>  tcf_action_rcu_free+0x39d/0x440 net/sched/act_api.c:378
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/1
> preempt_count: 101, expected: 0
> RCU nest depth: 0, expected: 0
> INFO: lockdep is turned off.
> Preemption disabled at:
> [<0000000000000000>] 0x0
> CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G        W           syzkaller #0 PREEMPT(full)
> Tainted: [W]=WARN
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <IRQ>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  __might_resched+0x378/0x4d0 kernel/sched/core.c:9163
>  __mutex_lock_common kernel/locking/mutex.c:623 [inline]
>  __mutex_lock+0x11c/0x1550 kernel/locking/mutex.c:820
>  __tcf_chain_put+0x60/0x820 net/sched/cls_api.c:694
>  free_tcf net/sched/act_api.c:130 [inline]
>  tcf_action_cleanup net/sched/act_api.c:370 [inline]
>  tcf_action_rcu_free+0x39d/0x440 net/sched/act_api.c:378
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  __do_softirq kernel/softirq.c:656 [inline]
>  invoke_softirq kernel/softirq.c:496 [inline]
>  __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
>  irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
>  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
>  sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
>  </IRQ>
>  <TASK>
>  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
> RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
> Code: 2b 7d 02 c3 cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 03 c2 1f 00 fb f4 <e9> 7c f7 02 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
> RSP: 0018:ffffc90000197e20 EFLAGS: 00000246
> RAX: ffff8882a9286000 RBX: ffffffff819a857a RCX: 0000000080000001
> RDX: 0000000000000001 RSI: ffffffff8c28b7c0 RDI: ffffffff819a857a
> RBP: ffffc90000197f10 R08: ffff88823c6339db R09: 1ffff110478c673b
> R10: dffffc0000000000 R11: ffffed10478c673c R12: 0000000000000001
> R13: 1ffff1102c09e000 R14: 0000000000000001 R15: 1ffff1102c09e000
>  arch_safe_halt arch/x86/kernel/process.c:766 [inline]
>  default_idle+0x9/0x20 arch/x86/kernel/process.c:767
>  default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
>  cpuidle_idle_call kernel/sched/idle.c:199 [inline]
>  do_idle+0x36a/0x5f0 kernel/sched/idle.c:352
>  cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451
>  start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
>  common_startup_64+0x13e/0x147
>  </TASK>
> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 5742, name: syz-executor
> preempt_count: 100, expected: 0
> RCU nest depth: 0, expected: 0
> INFO: lockdep is turned off.
> Preemption disabled at:
> [<ffffffff8187d090>] softirq_handle_begin kernel/softirq.c:463 [inline]
> [<ffffffff8187d090>] handle_softirqs+0xb0/0x840 kernel/softirq.c:598
> CPU: 1 UID: 0 PID: 5742 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full)
> Tainted: [W]=WARN
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <IRQ>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  __might_resched+0x378/0x4d0 kernel/sched/core.c:9163
>  __mutex_lock_common kernel/locking/mutex.c:623 [inline]
>  __mutex_lock+0x11c/0x1550 kernel/locking/mutex.c:820
>  __tcf_chain_put+0x60/0x820 net/sched/cls_api.c:694
>  free_tcf net/sched/act_api.c:130 [inline]
>  tcf_action_cleanup net/sched/act_api.c:370 [inline]
>  tcf_action_rcu_free+0x39d/0x440 net/sched/act_api.c:378
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  __do_softirq kernel/softirq.c:656 [inline]
>  invoke_softirq kernel/softirq.c:496 [inline]
>  __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
>  irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
>  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
>  sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
>  </IRQ>
>  <TASK>
>  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
> RIP: 0010:qlink_to_object mm/kasan/quarantine.c:140 [inline]
> RIP: 0010:qlink_free mm/kasan/quarantine.c:145 [inline]
> RIP: 0010:qlist_free_all+0x6f/0x100 mm/kasan/quarantine.c:179
> Code: 49 8b 44 04 08 89 c2 83 e2 01 48 ff ca 48 09 c2 48 21 ca 0f b6 42 33 c1 e0 18 3d 00 00 00 f5 49 0f 45 d5 4c 8b 62 08 49 8b 2f <49> 63 84 24 b8 00 00 00 49 29 c7 4c 89 e7 4c 89 fe e8 4b e4 ff ff
> RSP: 0018:ffffc90003e9f440 EFLAGS: 00000246
> RAX: 00000000f5000000 RBX: ffffc90003e9f478 RCX: ffffea0005c84b40
> RDX: ffffea0005c84b40 RSI: ffffea00044f5600 RDI: ffff88817212d150
> RBP: ffff88817263e598 R08: 0000000000000000 R09: ffffffff82310b6e
> R10: dffffc0000000000 R11: fffffbfff2061c3f R12: ffff888160417b40
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff88817212d150
>  kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
>  __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
>  kasan_slab_alloc include/linux/kasan.h:253 [inline]
>  slab_post_alloc_hook mm/slub.c:4570 [inline]
>  slab_alloc_node mm/slub.c:4899 [inline]
>  __do_kmalloc_node mm/slub.c:5295 [inline]
>  __kmalloc_node_noprof+0x498/0x7c0 mm/slub.c:5302
>  kmalloc_node_noprof include/linux/slab.h:1081 [inline]
>  __vmalloc_area_node mm/vmalloc.c:3857 [inline]
>  __vmalloc_node_range_noprof+0x5ef/0x1750 mm/vmalloc.c:4064
>  __vmalloc_node_noprof mm/vmalloc.c:4124 [inline]
>  vzalloc_noprof+0xb2/0xe0 mm/vmalloc.c:4202
>  alloc_counters+0x64/0x5d0 net/ipv4/netfilter/ip_tables.c:799
>  copy_entries_to_user net/ipv4/netfilter/ip_tables.c:821 [inline]
>  get_entries net/ipv4/netfilter/ip_tables.c:1022 [inline]
>  do_ipt_get_ctl+0xada/0x1240 net/ipv4/netfilter/ip_tables.c:1668
>  nf_getsockopt+0x26e/0x290 net/netfilter/nf_sockopt.c:116
>  ip_getsockopt+0x19e/0x230 net/ipv4/ip_sockglue.c:1777
>  do_sock_getsockopt+0x51d/0x7e0 net/socket.c:2487
>  __sys_getsockopt net/socket.c:2518 [inline]
>  __do_sys_getsockopt net/socket.c:2525 [inline]
>  __se_sys_getsockopt net/socket.c:2522 [inline]
>  __x64_sys_getsockopt+0x1a4/0x240 net/socket.c:2522
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f326419e62a
> Code: 48 83 ec 10 89 d2 48 63 ff 45 31 c9 6a 2a 45 31 c0 31 c9 e8 d8 99 fb ff 48 83 c4 18 c3 0f 1f 00 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 e8 ff ff ff f7
> RSP: 002b:00007ffd38f686c8 EFLAGS: 00000216 ORIG_RAX: 0000000000000037
> RAX: ffffffffffffffda RBX: 00007ffd38f68750 RCX: 00007f326419e62a
> RDX: 0000000000000041 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 0000000000000003 R08: 00007ffd38f686ec R09: ff78736871746264
> R10: 00007ffd38f68750 R11: 0000000000000216 R12: 00007f32643ecac0
> R13: 00007ffd38f686ec R14: 0000000000000000 R15: 00007f32643ed180
>  </TASK>
> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:623
> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 23, name: ksoftirqd/1
> preempt_count: 100, expected: 0
> RCU nest depth: 0, expected: 0
> INFO: lockdep is turned off.
> Preemption disabled at:
> [<ffffffff8187d090>] softirq_handle_begin kernel/softirq.c:463 [inline]
> [<ffffffff8187d090>] handle_softirqs+0xb0/0x840 kernel/softirq.c:598
> CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Tainted: G        W           syzkaller #0 PREEMPT(full)
> Tainted: [W]=WARN
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  __might_resched+0x378/0x4d0 kernel/sched/core.c:9163
>  __mutex_lock_common kernel/locking/mutex.c:623 [inline]
>  __mutex_lock+0x11c/0x1550 kernel/locking/mutex.c:820
>  __tcf_chain_put+0x60/0x820 net/sched/cls_api.c:694
>  free_tcf net/sched/act_api.c:130 [inline]
>  tcf_action_cleanup net/sched/act_api.c:370 [inline]
>  tcf_action_rcu_free+0x39d/0x440 net/sched/act_api.c:378
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
> ----------------
> Code disassembly (best guess):
>    0:   2b 7d 02                sub    0x2(%rbp),%edi
>    3:   c3                      ret
>    4:   cc                      int3
>    5:   cc                      int3
>    6:   cc                      int3
>    7:   cc                      int3
>    8:   cc                      int3
>    9:   cc                      int3
>    a:   cc                      int3
>    b:   90                      nop
>    c:   90                      nop
>    d:   90                      nop
>    e:   90                      nop
>    f:   90                      nop
>   10:   90                      nop
>   11:   90                      nop
>   12:   90                      nop
>   13:   90                      nop
>   14:   90                      nop
>   15:   90                      nop
>   16:   90                      nop
>   17:   90                      nop
>   18:   90                      nop
>   19:   90                      nop
>   1a:   90                      nop
>   1b:   f3 0f 1e fa             endbr64
>   1f:   eb 07                   jmp    0x28
>   21:   0f 00 2d 03 c2 1f 00    verw   0x1fc203(%rip)        # 0x1fc22b
>   28:   fb                      sti
>   29:   f4                      hlt
> * 2a:   e9 7c f7 02 00          jmp    0x2f7ab <-- trapping instruction
>   2f:   cc                      int3
>   30:   cc                      int3
>   31:   cc                      int3
>   32:   cc                      int3
>   33:   cc                      int3
>   34:   cc                      int3
>   35:   cc                      int3
>   36:   cc                      int3
>   37:   cc                      int3
>   38:   cc                      int3
>   39:   cc                      int3
>   3a:   cc                      int3
>   3b:   90                      nop
>   3c:   90                      nop
>   3d:   90                      nop
>   3e:   90                      nop
>   3f:   90                      nop
>
>
> ***
>
> inconsistent lock state in tcf_mirred_release
>
> tree:      net
> URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/netdev/net.git
> base:      78ef59e7a6459b16f8102e0ee1c718443323d1af
> arch:      amd64
> compiler:  Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> config:    https://ci.syzbot.org/builds/46884a04-6831-455e-8868-d463d6e018db/config
> syz repro: https://ci.syzbot.org/findings/339567f1-aefa-440b-b74d-8584664a549d/syz_repro
>
> ================================
> WARNING: inconsistent lock state
> syzkaller #0 Not tainted
> --------------------------------
> inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
> ksoftirqd/1/23 [HC0[0]:SC1[1]:HE1:SE0] takes:
> ffffffff8fe24698 (mirred_list_lock){+.?.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
> ffffffff8fe24698 (mirred_list_lock){+.?.}-{3:3}, at: tcf_mirred_release+0x2c/0x1c0 net/sched/act_mirred.c:78
> {SOFTIRQ-ON-W} state was registered at:
>   lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
>   __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
>   _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
>   spin_lock include/linux/spinlock.h:342 [inline]
>   mirred_device_event+0x80/0x2c0 net/sched/act_mirred.c:561
>   notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
>   call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
>   call_netdevice_notifiers net/core/dev.c:2301 [inline]
>   unregister_netdevice_many_notify+0x17a5/0x22c0 net/core/dev.c:12421
>   ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
>   ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
>   cleanup_net+0x56b/0x800 net/core/net_namespace.c:702
>   process_one_work kernel/workqueue.c:3314 [inline]
>   process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
>   worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
>   kthread+0x389/0x470 kernel/kthread.c:436
>   ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> irq event stamp: 953728
> hardirqs last  enabled at (953728): [<ffffffff8bac5040>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline]
> hardirqs last  enabled at (953728): [<ffffffff8bac5040>] _raw_spin_unlock_irqrestore+0x30/0x80 kernel/locking/spinlock.c:198
> hardirqs last disabled at (953727): [<ffffffff8bac4e9a>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:130 [inline]
> hardirqs last disabled at (953727): [<ffffffff8bac4e9a>] _raw_spin_lock_irqsave+0x1a/0x60 kernel/locking/spinlock.c:166
> softirqs last  enabled at (953336): [<ffffffff8187fb46>] run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
> softirqs last disabled at (953341): [<ffffffff8187fb46>] run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>
> other info that might help us debug this:
>  Possible unsafe locking scenario:
>
>        CPU0
>        ----
>   lock(mirred_list_lock);
>   <Interrupt>
>     lock(mirred_list_lock);
>
>  *** DEADLOCK ***
>
> 1 lock held by ksoftirqd/1/23:
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_do_batch kernel/rcu/tree.c:2611 [inline]
>  #0: ffffffff8e95ce00 (rcu_callback){....}-{0:0}, at: rcu_core+0x751/0x1070 kernel/rcu/tree.c:2869
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 23 Comm: ksoftirqd/1 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_usage_bug+0x28b/0x2e0 kernel/locking/lockdep.c:4042
>  valid_state kernel/locking/lockdep.c:4056 [inline]
>  mark_lock_irq+0x410/0x420 kernel/locking/lockdep.c:-1
>  mark_lock+0x115/0x190 kernel/locking/lockdep.c:4753
>  mark_usage kernel/locking/lockdep.c:-1 [inline]
>  __lock_acquire+0x689/0x2cf0 kernel/locking/lockdep.c:5191
>  lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
>  __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
>  _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
>  spin_lock include/linux/spinlock.h:342 [inline]
>  tcf_mirred_release+0x2c/0x1c0 net/sched/act_mirred.c:78
>  tcf_action_cleanup net/sched/act_api.c:367 [inline]
>  tcf_action_rcu_free+0x2bd/0x440 net/sched/act_api.c:378
>  rcu_do_batch kernel/rcu/tree.c:2617 [inline]
>  rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
>  handle_softirqs+0x22a/0x840 kernel/softirq.c:622
>  run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
>  smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
>  kthread+0x389/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
>
>
> ***
>
> If these findings have caused you to resend the series or submit a
> separate fix, please add the following tag to your commit message:
>   Tested-by: syzbot@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ---
> This report is generated by a bot. It may contain errors.
> syzbot ci engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
> To test a patch for this bug, please reply with `#syz test`
> (should be on a separate line).
>
> The patch should be attached to the email.
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