openvswitch: netlink: Actions may not be safe on all matching packets ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.1.4133/19213 is trying to acquire lock: ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:316 [inline] ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4636 [inline] ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4974 [inline] ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:5413 [inline] ffffffff8ee8f980 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_noprof+0xbc/0x720 mm/slub.c:5439 but task is already holding lock: ffffffff8ee69aa0 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0x231/0x1900 mm/percpu.c:1796 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (pcpu_alloc_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 pcpu_alloc_noprof+0x231/0x1900 mm/percpu.c:1796 percpu_ref_init+0x42/0x350 lib/percpu-refcount.c:72 blkg_alloc+0xee/0x8f0 block/blk-cgroup.c:316 blkg_conf_prep+0x60b/0xd80 block/blk-cgroup.c:879 tg_set_conf+0x20b/0x4e0 block/blk-throttle.c:1373 cgroup_file_write+0x331/0x8f0 kernel/cgroup/cgroup.c:4412 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x612/0xba0 fs/read_write.c:687 ksys_write+0x150/0x270 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&q->blkcg_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 blkcg_activate_policy+0x1cb/0x8e0 block/blk-cgroup.c:1608 blk_throtl_init+0x2f7/0x420 block/blk-throttle.c:1339 tg_set_conf+0x1db/0x4e0 block/blk-throttle.c:1368 cgroup_file_write+0x331/0x8f0 kernel/cgroup/cgroup.c:4412 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x612/0xba0 fs/read_write.c:687 ksys_write+0x150/0x270 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#17){++++}-{0:0}: blk_alloc_queue+0x544/0x690 block/blk-core.c:504 blk_mq_alloc_queue block/blk-mq.c:4420 [inline] __blk_mq_alloc_disk+0x194/0x390 block/blk-mq.c:4467 loop_add+0x480/0xb40 drivers/block/loop.c:2071 loop_init+0xd7/0x160 drivers/block/loop.c:2310 do_one_initcall+0x250/0x870 init/main.c:1357 do_initcall_level+0x10a/0x1a0 init/main.c:1419 do_initcalls+0x59/0xa0 init/main.c:1435 kernel_init_freeable+0x29d/0x3e0 init/main.c:1670 kernel_init+0x22/0x1d0 init/main.c:1560 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (fs_reclaim){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908 __fs_reclaim_acquire mm/page_alloc.c:4375 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4389 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4636 [inline] slab_alloc_node mm/slub.c:4974 [inline] __do_kmalloc_node mm/slub.c:5413 [inline] __kmalloc_noprof+0xbc/0x720 mm/slub.c:5439 _kmalloc_noprof include/linux/slab.h:995 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] alloc_pages_bulk_weighted_interleave mm/mempolicy.c:2682 [inline] alloc_pages_bulk_mempolicy_noprof+0xaef/0x1690 mm/mempolicy.c:2785 vm_area_alloc_pages mm/vmalloc.c:3736 [inline] __vmalloc_area_node mm/vmalloc.c:3914 [inline] __vmalloc_node_range_noprof+0xa0a/0x1540 mm/vmalloc.c:4104 __vmalloc_node_noprof mm/vmalloc.c:4165 [inline] __vmalloc_noprof+0xd2/0x120 mm/vmalloc.c:4181 pcpu_mem_zalloc mm/percpu.c:512 [inline] pcpu_alloc_chunk mm/percpu.c:1449 [inline] pcpu_create_chunk+0x1cb/0xc30 mm/percpu-vm.c:359 pcpu_alloc_noprof+0x73e/0x1900 mm/percpu.c:1852 bpf_map_alloc_percpu+0x65/0x180 kernel/bpf/syscall.c:583 prealloc_init+0x214/0x650 kernel/bpf/hashtab.c:339 htab_map_alloc+0x6a0/0xc90 kernel/bpf/hashtab.c:639 map_create_alloc kernel/bpf/syscall.c:1534 [inline] map_create+0xf3d/0x1b70 kernel/bpf/syscall.c:1644 __sys_bpf+0xaea/0xd90 kernel/bpf/syscall.c:6344 __do_sys_bpf kernel/bpf/syscall.c:6486 [inline] __se_sys_bpf kernel/bpf/syscall.c:6483 [inline] __x64_sys_bpf+0xba/0xd0 kernel/bpf/syscall.c:6483 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: fs_reclaim --> &q->blkcg_mutex --> pcpu_alloc_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(pcpu_alloc_mutex); lock(&q->blkcg_mutex); lock(pcpu_alloc_mutex); lock(fs_reclaim); *** DEADLOCK *** locks held by syz.1.4133/19213: 1, last CPU#1: #0: ffffffff8ee69aa0 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0x231/0x1900 mm/percpu.c:1796 stack backtrace: CPU: 1 UID: 0 PID: 19213 Comm: syz.1.4133 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2059 check_noncircular+0x12f/0x150 kernel/locking/lockdep.c:2191 check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x15ff/0x2e50 kernel/locking/lockdep.c:5254 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5908 __fs_reclaim_acquire mm/page_alloc.c:4375 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4389 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4636 [inline] slab_alloc_node mm/slub.c:4974 [inline] __do_kmalloc_node mm/slub.c:5413 [inline] __kmalloc_noprof+0xbc/0x720 mm/slub.c:5439 _kmalloc_noprof include/linux/slab.h:995 [inline] _kzalloc_noprof include/linux/slab.h:1312 [inline] alloc_pages_bulk_weighted_interleave mm/mempolicy.c:2682 [inline] alloc_pages_bulk_mempolicy_noprof+0xaef/0x1690 mm/mempolicy.c:2785 vm_area_alloc_pages mm/vmalloc.c:3736 [inline] __vmalloc_area_node mm/vmalloc.c:3914 [inline] __vmalloc_node_range_noprof+0xa0a/0x1540 mm/vmalloc.c:4104 __vmalloc_node_noprof mm/vmalloc.c:4165 [inline] __vmalloc_noprof+0xd2/0x120 mm/vmalloc.c:4181 pcpu_mem_zalloc mm/percpu.c:512 [inline] pcpu_alloc_chunk mm/percpu.c:1449 [inline] pcpu_create_chunk+0x1cb/0xc30 mm/percpu-vm.c:359 pcpu_alloc_noprof+0x73e/0x1900 mm/percpu.c:1852 bpf_map_alloc_percpu+0x65/0x180 kernel/bpf/syscall.c:583 prealloc_init+0x214/0x650 kernel/bpf/hashtab.c:339 htab_map_alloc+0x6a0/0xc90 kernel/bpf/hashtab.c:639 map_create_alloc kernel/bpf/syscall.c:1534 [inline] map_create+0xf3d/0x1b70 kernel/bpf/syscall.c:1644 __sys_bpf+0xaea/0xd90 kernel/bpf/syscall.c:6344 __do_sys_bpf kernel/bpf/syscall.c:6486 [inline] __se_sys_bpf kernel/bpf/syscall.c:6483 [inline] __x64_sys_bpf+0xba/0xd0 kernel/bpf/syscall.c:6483 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fde45b9e159 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fde469a4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007fde45e25fa0 RCX: 00007fde45b9e159 RDX: 0000000000000050 RSI: 0000200000000940 RDI: 1101000000000000 RBP: 00007fde45c35024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fde45e26038 R14: 00007fde45e25fa0 R15: 00007fde45f4fa48