syzbot

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc5-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/21938 is trying to acquire lock:
ffff88813fffece0 (&pgdat->kswapd_wait){..-.}-{2:2}, at: __wake_up_common_lock+0x25/0x1e0 kernel/sched/wait.c:105

but task is already holding lock:
ffff888030a651f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xcb/0xc10 kernel/bpf/lpm_trie.c:324

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&trie->lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       trie_delete_elem+0x96/0x6a0 kernel/bpf/lpm_trie.c:451
       0xffffffffa0002355
       bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
       __bpf_prog_run include/linux/filter.h:657 [inline]
       bpf_prog_run include/linux/filter.h:664 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
       bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
       trace_tlb_flush+0x118/0x140 include/trace/events/tlb.h:38
       switch_mm_irqs_off+0x7cb/0xae0
       context_switch kernel/sched/core.c:5393 [inline]
       __schedule+0x1066/0x4a00 kernel/sched/core.c:6746
       preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6925
       preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6949
       preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:12
       unwind_next_frame+0x2124/0x2a00 arch/x86/kernel/unwind_orc.c:672
       arch_stack_walk+0x151/0x1b0 arch/x86/kernel/stacktrace.c:25
       stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
       kasan_save_stack mm/kasan/common.c:47 [inline]
       kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
       unpoison_slab_object mm/kasan/common.c:312 [inline]
       __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
       kasan_slab_alloc include/linux/kasan.h:201 [inline]
       slab_post_alloc_hook mm/slub.c:3798 [inline]
       slab_alloc_node mm/slub.c:3845 [inline]
       kmem_cache_alloc+0x174/0x340 mm/slub.c:3852
       kmem_cache_zalloc include/linux/slab.h:739 [inline]
       alloc_buffer_head+0x2d/0x2a0 fs/buffer.c:3001
       folio_alloc_buffers+0x2da/0x840 fs/buffer.c:924
       grow_dev_folio fs/buffer.c:1067 [inline]
       grow_buffers fs/buffer.c:1108 [inline]
       __getblk_slow fs/buffer.c:1134 [inline]
       bdev_getblk+0x305/0x610 fs/buffer.c:1429
       __bread_gfp+0xac/0x430 fs/buffer.c:1474
       sb_bread include/linux/buffer_head.h:321 [inline]
       bfs_find_entry+0x1c3/0x3f0 fs/bfs/dir.c:333
       bfs_lookup+0x14b/0x270 fs/bfs/dir.c:137
       __lookup_slow+0x28c/0x3f0 fs/namei.c:1692
       lookup_slow+0x53/0x70 fs/namei.c:1709
       walk_component+0x2e1/0x410 fs/namei.c:2004
       lookup_last fs/namei.c:2461 [inline]
       path_lookupat+0x16f/0x450 fs/namei.c:2485
       filename_lookup+0x256/0x610 fs/namei.c:2514
       user_path_at_empty+0x42/0x60 fs/namei.c:2921
       user_path_at include/linux/namei.h:57 [inline]
       do_mount fs/namespace.c:3689 [inline]
       __do_sys_mount fs/namespace.c:3898 [inline]
       __se_sys_mount+0x29a/0x3c0 fs/namespace.c:3875
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
       raw_spin_rq_lock kernel/sched/sched.h:1387 [inline]
       rq_lock kernel/sched/sched.h:1701 [inline]
       task_fork_fair+0x61/0x1e0 kernel/sched/fair.c:12635
       sched_cgroup_fork+0x37c/0x410 kernel/sched/core.c:4845
       copy_process+0x2217/0x3df0 kernel/fork.c:2499
       kernel_clone+0x223/0x870 kernel/fork.c:2797
       user_mode_thread+0x132/0x1a0 kernel/fork.c:2875
       rest_init+0x23/0x300 init/main.c:704
       start_kernel+0x47a/0x500 init/main.c:1081
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
       x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:488
       common_startup_64+0x13e/0x147

-> #1 (&p->pi_lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:553 [inline]
       try_to_wake_up+0xb0/0x1470 kernel/sched/core.c:4262
       autoremove_wake_function+0x16/0x110 kernel/sched/wait.c:384
       __wake_up_common kernel/sched/wait.c:89 [inline]
       __wake_up_common_lock+0x130/0x1e0 kernel/sched/wait.c:106
       rmqueue mm/page_alloc.c:2919 [inline]
       get_page_from_freelist+0x30f1/0x35b0 mm/page_alloc.c:3314
       __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
       alloc_pages_mpol+0x3e8/0x680 mm/mempolicy.c:2264
       alloc_pages mm/mempolicy.c:2335 [inline]
       folio_alloc+0x128/0x180 mm/mempolicy.c:2342
       filemap_alloc_folio+0xdf/0x500 mm/filemap.c:984
       __filemap_get_folio+0x41a/0xbb0 mm/filemap.c:1926
       grow_dev_folio fs/buffer.c:1042 [inline]
       grow_buffers fs/buffer.c:1108 [inline]
       __getblk_slow fs/buffer.c:1134 [inline]
       bdev_getblk+0x234/0x610 fs/buffer.c:1429
       __bread_gfp+0xac/0x430 fs/buffer.c:1474
       sb_bread include/linux/buffer_head.h:321 [inline]
       bfs_find_entry+0x1c3/0x3f0 fs/bfs/dir.c:333
       bfs_lookup+0x14b/0x270 fs/bfs/dir.c:137
       __lookup_slow+0x28c/0x3f0 fs/namei.c:1692
       lookup_slow+0x53/0x70 fs/namei.c:1709
       walk_component+0x2e1/0x410 fs/namei.c:2004
       lookup_last fs/namei.c:2461 [inline]
       path_lookupat+0x16f/0x450 fs/namei.c:2485
       filename_lookup+0x256/0x610 fs/namei.c:2514
       user_path_at_empty+0x42/0x60 fs/namei.c:2921
       user_path_at include/linux/namei.h:57 [inline]
       do_mount fs/namespace.c:3689 [inline]
       __do_sys_mount fs/namespace.c:3898 [inline]
       __se_sys_mount+0x29a/0x3c0 fs/namespace.c:3875
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&pgdat->kswapd_wait){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       __wake_up_common_lock+0x25/0x1e0 kernel/sched/wait.c:105
       rmqueue mm/page_alloc.c:2919 [inline]
       get_page_from_freelist+0x30f1/0x35b0 mm/page_alloc.c:3314
       __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
       __alloc_pages_node include/linux/gfp.h:238 [inline]
       alloc_pages_node include/linux/gfp.h:261 [inline]
       __kmalloc_large_node+0x91/0x1f0 mm/slub.c:3911
       __do_kmalloc_node mm/slub.c:3954 [inline]
       __kmalloc_node+0x33e/0x4e0 mm/slub.c:3973
       kmalloc_node include/linux/slab.h:648 [inline]
       bpf_map_kmalloc_node+0xd3/0x1c0 kernel/bpf/syscall.c:422
       lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
       trie_update_elem+0x1d3/0xc10 kernel/bpf/lpm_trie.c:333
       bpf_map_update_value+0x4d3/0x540 kernel/bpf/syscall.c:203
       map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
       __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5648
       __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
       __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
       __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  &pgdat->kswapd_wait --> &rq->__lock --> &trie->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&trie->lock);
                               lock(&rq->__lock);
                               lock(&trie->lock);
  lock(&pgdat->kswapd_wait);

 *** DEADLOCK ***

2 locks held by syz-executor.3/21938:
 #0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #0: ffffffff8e334d20 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x3c4/0x540 kernel/bpf/syscall.c:202
 #1: ffff888030a651f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xcb/0xc10 kernel/bpf/lpm_trie.c:324

stack backtrace:
CPU: 0 PID: 21938 Comm: syz-executor.3 Not tainted 6.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
 __wake_up_common_lock+0x25/0x1e0 kernel/sched/wait.c:105
 rmqueue mm/page_alloc.c:2919 [inline]
 get_page_from_freelist+0x30f1/0x35b0 mm/page_alloc.c:3314
 __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 __kmalloc_large_node+0x91/0x1f0 mm/slub.c:3911
 __do_kmalloc_node mm/slub.c:3954 [inline]
 __kmalloc_node+0x33e/0x4e0 mm/slub.c:3973
 kmalloc_node include/linux/slab.h:648 [inline]
 bpf_map_kmalloc_node+0xd3/0x1c0 kernel/bpf/syscall.c:422
 lpm_trie_node_alloc kernel/bpf/lpm_trie.c:291 [inline]
 trie_update_elem+0x1d3/0xc10 kernel/bpf/lpm_trie.c:333
 bpf_map_update_value+0x4d3/0x540 kernel/bpf/syscall.c:203
 map_update_elem+0x53a/0x6f0 kernel/bpf/syscall.c:1641
 __sys_bpf+0x76f/0x810 kernel/bpf/syscall.c:5648
 __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
 __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3f3bc7dea9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3f3cad30c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f3f3bdabf80 RCX: 00007f3f3bc7dea9
RDX: 0000000000000020 RSI: 0000000020000080 RDI: 0000000000000002
RBP: 00007f3f3bcca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f3f3bdabf80 R15: 00007fff194b95a8
 </TASK>