====================================================== WARNING: possible circular locking dependency detected 4.19.138-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/14297 is trying to acquire lock: 00000000d0ae0428 ((&q->adapt_timer)){+.-.}, at: arch_local_irq_disable arch/x86/include/asm/paravirt.h:794 [inline] 00000000d0ae0428 ((&q->adapt_timer)){+.-.}, at: arch_local_irq_save arch/x86/include/asm/paravirt.h:807 [inline] 00000000d0ae0428 ((&q->adapt_timer)){+.-.}, at: del_timer_sync+0x75/0x270 kernel/time/timer.c:1294 but task is already holding lock: 00000000d329f4b8 (&qdisc_tx_lock){+.-.}, at: spin_lock_bh include/linux/spinlock.h:334 [inline] 00000000d329f4b8 (&qdisc_tx_lock){+.-.}, at: sch_tree_lock include/net/sch_generic.h:477 [inline] 00000000d329f4b8 (&qdisc_tx_lock){+.-.}, at: red_change+0x379/0x1080 net/sched/sch_red.c:230 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&qdisc_tx_lock){+.-.}: spin_lock include/linux/spinlock.h:329 [inline] red_adaptative_timer+0x92/0x5c0 net/sched/sch_red.c:265 call_timer_fn+0x177/0x700 kernel/time/timer.c:1338 expire_timers+0x243/0x4e0 kernel/time/timer.c:1375 __run_timers kernel/time/timer.c:1703 [inline] run_timer_softirq+0x21c/0x670 kernel/time/timer.c:1716 __do_softirq+0x26c/0x9a0 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x215/0x260 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:544 [inline] smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1094 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 __read_once_size include/linux/compiler.h:193 [inline] check_kcov_mode kernel/kcov.c:69 [inline] write_comp_data+0x23/0x70 kernel/kcov.c:122 compound_head include/linux/page-flags.h:144 [inline] get_page include/linux/mm.h:931 [inline] copy_one_pte mm/memory.c:1040 [inline] copy_pte_range mm/memory.c:1102 [inline] copy_pmd_range mm/memory.c:1153 [inline] copy_pud_range mm/memory.c:1187 [inline] copy_p4d_range mm/memory.c:1209 [inline] copy_page_range+0x1038/0x2ff0 mm/memory.c:1271 dup_mmap kernel/fork.c:549 [inline] dup_mm kernel/fork.c:1288 [inline] copy_mm kernel/fork.c:1344 [inline] copy_process.part.0+0x5c40/0x7f40 kernel/fork.c:1897 copy_process kernel/fork.c:1694 [inline] _do_fork+0x22f/0xf30 kernel/fork.c:2207 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 ((&q->adapt_timer)){+.-.}: del_timer_sync+0xab/0x270 kernel/time/timer.c:1295 red_destroy+0x15/0x60 net/sched/sch_red.c:182 qdisc_destroy+0x180/0x780 net/sched/sch_generic.c:983 red_change+0x514/0x1080 net/sched/sch_red.c:236 qdisc_change net/sched/sch_api.c:1239 [inline] tc_modify_qdisc+0xf6a/0x1a80 net/sched/sch_api.c:1542 rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4778 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:632 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115 __sys_sendmsg net/socket.c:2153 [inline] __do_sys_sendmsg net/socket.c:2162 [inline] __se_sys_sendmsg net/socket.c:2160 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&qdisc_tx_lock); lock((&q->adapt_timer)); lock(&qdisc_tx_lock); lock((&q->adapt_timer)); *** DEADLOCK *** 2 locks held by syz-executor.4/14297: #0: 00000000f01be3ed (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 00000000f01be3ed (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4775 #1: 00000000d329f4b8 (&qdisc_tx_lock){+.-.}, at: spin_lock_bh include/linux/spinlock.h:334 [inline] #1: 00000000d329f4b8 (&qdisc_tx_lock){+.-.}, at: sch_tree_lock include/net/sch_generic.h:477 [inline] #1: 00000000d329f4b8 (&qdisc_tx_lock){+.-.}, at: red_change+0x379/0x1080 net/sched/sch_red.c:230 stack backtrace: CPU: 0 PID: 14297 Comm: syz-executor.4 Not tainted 4.19.138-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2fe lib/dump_stack.c:118 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1221 check_prev_add kernel/locking/lockdep.c:1865 [inline] check_prevs_add kernel/locking/lockdep.c:1978 [inline] validate_chain kernel/locking/lockdep.c:2419 [inline] __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3415 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3907 del_timer_sync+0xab/0x270 kernel/time/timer.c:1295 red_destroy+0x15/0x60 net/sched/sch_red.c:182 qdisc_destroy+0x180/0x780 net/sched/sch_generic.c:983 red_change+0x514/0x1080 net/sched/sch_red.c:236 qdisc_change net/sched/sch_api.c:1239 [inline] tc_modify_qdisc+0xf6a/0x1a80 net/sched/sch_api.c:1542 rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4778 netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xc3/0x120 net/socket.c:632 ___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115 __sys_sendmsg net/socket.c:2153 [inline] __do_sys_sendmsg net/socket.c:2162 [inline] __se_sys_sendmsg net/socket.c:2160 [inline] __x64_sys_sendmsg+0x132/0x220 net/socket.c:2160 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45ce69 Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f67b1292c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000002c100 RCX: 000000000045ce69 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 00007ffc34f78f6f R14: 00007f67b12939c0 R15: 000000000118bf2c Scheduler tracepoints stat_sleep, stat_iowait, stat_blocked and stat_runtime require the kernel parameter schedstats=enable or kernel.sched_schedstats=1