syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.212/5153 is trying to acquire lock:
ffff88813fffacd8 (&zone->lock){-.-.}-{2:2}, at: rmqueue_buddy mm/page_alloc.c:3724 [inline]
ffff88813fffacd8 (&zone->lock){-.-.}-{2:2}, at: rmqueue mm/page_alloc.c:3877 [inline]
ffff88813fffacd8 (&zone->lock){-.-.}-{2:2}, at: get_page_from_freelist+0x912/0x1ac0 mm/page_alloc.c:4325

but task is already holding lock:
ffff8880742a4238 (&trie->lock){....}-{2:2}, at: trie_update_elem+0xc4/0xe90 kernel/bpf/lpm_trie.c:335

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&trie->lock){....}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
       trie_delete_elem+0x90/0x690 kernel/bpf/lpm_trie.c:467
       0xffffffffa0001fb1
       bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
       __bpf_prog_run include/linux/filter.h:607 [inline]
       bpf_prog_run include/linux/filter.h:614 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
       bpf_trace_run5+0x211/0x440 kernel/trace/bpf_trace.c:2327
       __bpf_trace_mm_page_alloc_extfrag+0xe9/0x110 include/trace/events/kmem.h:266
       trace_mm_page_alloc_extfrag+0x168/0x1b0 include/trace/events/kmem.h:266
       __rmqueue_fallback mm/page_alloc.c:3075 [inline]
       __rmqueue mm/page_alloc.c:3112 [inline]
       rmqueue_bulk mm/page_alloc.c:3133 [inline]
       __rmqueue_pcplist+0x786/0xfb0 mm/page_alloc.c:3785
       rmqueue_pcplist mm/page_alloc.c:3827 [inline]
       rmqueue mm/page_alloc.c:3870 [inline]
       get_page_from_freelist+0x7cd/0x1ac0 mm/page_alloc.c:4325
       __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
       alloc_slab_page+0x5d/0x160 mm/slub.c:1799
       allocate_slab mm/slub.c:1944 [inline]
       new_slab+0x87/0x2c0 mm/slub.c:1997
       ___slab_alloc+0xbc6/0x1230 mm/slub.c:3154
       __slab_alloc mm/slub.c:3240 [inline]
       slab_alloc_node mm/slub.c:3325 [inline]
       __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
       __do_kmalloc_node mm/slab_common.c:935 [inline]
       __kmalloc_node+0xa0/0x240 mm/slab_common.c:943
       kmalloc_node include/linux/slab.h:589 [inline]
       kvmalloc_node+0x6c/0x180 mm/util.c:581
       kvmalloc include/linux/slab.h:716 [inline]
       kvmalloc_array include/linux/slab.h:734 [inline]
       __ptr_ring_init_queue_alloc include/linux/ptr_ring.h:471 [inline]
       ptr_ring_init include/linux/ptr_ring.h:489 [inline]
       skb_array_init include/linux/skb_array.h:182 [inline]
       pfifo_fast_init+0x109/0x6a0 net/sched/sch_generic.c:870
       qdisc_create_dflt+0x11a/0x4b0 net/sched/sch_generic.c:1019
       mq_init+0x2df/0x660 net/sched/sch_mq.c:90
       qdisc_create_dflt+0x11a/0x4b0 net/sched/sch_generic.c:1019
       attach_default_qdiscs net/sched/sch_generic.c:1199 [inline]
       dev_activate+0x1cc/0x11a0 net/sched/sch_generic.c:1253
       __dev_open+0x334/0x420 net/core/dev.c:1497
       __dev_change_flags+0x20a/0x6a0 net/core/dev.c:8638
       dev_change_flags+0x82/0x1a0 net/core/dev.c:8709
       dev_ifsioc+0x12a/0xcd0 net/core/dev_ioctl.c:326
       dev_ioctl+0x55e/0xe80 net/core/dev_ioctl.c:572
       sock_do_ioctl+0x222/0x2f0 net/socket.c:1215
       sock_ioctl+0x4df/0x6d0 net/socket.c:1320
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&zone->lock){-.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
       rmqueue_buddy mm/page_alloc.c:3724 [inline]
       rmqueue mm/page_alloc.c:3877 [inline]
       get_page_from_freelist+0x912/0x1ac0 mm/page_alloc.c:4325
       __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
       __alloc_pages_node include/linux/gfp.h:237 [inline]
       alloc_pages_node include/linux/gfp.h:260 [inline]
       __kmalloc_large_node+0x8c/0x1e0 mm/slab_common.c:1077
       __do_kmalloc_node mm/slab_common.c:924 [inline]
       __kmalloc_node+0x10e/0x240 mm/slab_common.c:943
       kmalloc_node include/linux/slab.h:589 [inline]
       bpf_map_kmalloc_node+0xb8/0x1a0 kernel/bpf/syscall.c:454
       lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
       trie_update_elem+0x160/0xe90 kernel/bpf/lpm_trie.c:338
       bpf_map_update_value+0x59e/0x670 kernel/bpf/syscall.c:228
       map_update_elem+0x4d7/0x680 kernel/bpf/syscall.c:1473
       __sys_bpf+0x454/0x6d0 kernel/bpf/syscall.c:5018
       __do_sys_bpf kernel/bpf/syscall.c:5134 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5132 [inline]
       __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5132
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&trie->lock);
                               lock(&zone->lock);
                               lock(&trie->lock);
  lock(&zone->lock);

 *** DEADLOCK ***

2 locks held by syz.0.212/5153:
 #0: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x375/0x670 kernel/bpf/syscall.c:227
 #1: ffff8880742a4238 (&trie->lock){....}-{2:2}, at: trie_update_elem+0xc4/0xe90 kernel/bpf/lpm_trie.c:335

stack backtrace:
CPU: 1 PID: 5153 Comm: syz.0.212 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
 rmqueue_buddy mm/page_alloc.c:3724 [inline]
 rmqueue mm/page_alloc.c:3877 [inline]
 get_page_from_freelist+0x912/0x1ac0 mm/page_alloc.c:4325
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x8c/0x1e0 mm/slab_common.c:1077
 __do_kmalloc_node mm/slab_common.c:924 [inline]
 __kmalloc_node+0x10e/0x240 mm/slab_common.c:943
 kmalloc_node include/linux/slab.h:589 [inline]
 bpf_map_kmalloc_node+0xb8/0x1a0 kernel/bpf/syscall.c:454
 lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
 trie_update_elem+0x160/0xe90 kernel/bpf/lpm_trie.c:338
 bpf_map_update_value+0x59e/0x670 kernel/bpf/syscall.c:228
 map_update_elem+0x4d7/0x680 kernel/bpf/syscall.c:1473
 __sys_bpf+0x454/0x6d0 kernel/bpf/syscall.c:5018
 __do_sys_bpf kernel/bpf/syscall.c:5134 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5132 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5132
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5a74b8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5a75a8b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f5a74de5fa0 RCX: 00007f5a74b8f749
RDX: 0000000000000020 RSI: 0000200000000080 RDI: 0000000000000002
RBP: 00007f5a74c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5a74de6038 R14: 00007f5a74de5fa0 R15: 00007ffdccde0b68
 </TASK>