syzbot

BUG: sleeping function called from invalid context at include/linux/sched/mm.h:209
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 3486, name: syz-executor313
2 locks held by syz-executor313/3486:
 #0: ffffffff8d9e1148 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d9e1148 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x94c/0xee0 net/core/rtnetlink.c:5600
 #1: ffff88801f031908 (&sch->q.lock){+...}-{2:2}, at: netem_change+0x257/0x20c0 net/sched/sch_netem.c:972
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 0 PID: 3486 Comm: syz-executor313 Not tainted 5.15.126-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 ___might_sleep+0x547/0x6a0 kernel/sched/core.c:9625
 might_alloc include/linux/sched/mm.h:209 [inline]
 slab_pre_alloc_hook+0x44/0xc0 mm/slab.h:492
 slab_alloc_node mm/slub.c:3134 [inline]
 __kmalloc_node+0x71/0x390 mm/slub.c:4451
 kmalloc_node include/linux/slab.h:614 [inline]
 kvmalloc_node+0x80/0x140 mm/util.c:619
 kvmalloc include/linux/mm.h:805 [inline]
 get_dist_table+0x83/0x2c0 net/sched/sch_netem.c:788
 netem_change+0xa6a/0x20c0 net/sched/sch_netem.c:995
 netem_init+0x58/0xb0 net/sched/sch_netem.c:1075
 qdisc_create+0x8ae/0x1390 net/sched/sch_api.c:1264
 tc_modify_qdisc+0xac5/0x1710
 rtnetlink_rcv_msg+0x993/0xee0 net/core/rtnetlink.c:5603
 netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2505
 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
 netlink_unicast+0x7b6/0x980 net/netlink/af_netlink.c:1356
 netlink_sendmsg+0xa30/0xd60 net/netlink/af_netlink.c:1924
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
 __sys_sendmsg net/socket.c:2495 [inline]
 __do_sys_sendmsg net/socket.c:2504 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2502
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fe1e63214e9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff21504588 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fff21504758 RCX: 00007fe1e63214e9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00007fe1e6394610 R08: 00000000ffffffff R09: 00007fff21504758
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff21504748 R14: 0000000000000001 R15: 0000000000000001
 </TASK>

============================================
WARNING: possible recursive locking detected
5.15.126-syzkaller #0 Tainted: G        W        
--------------------------------------------
syz-executor313/3486 is trying to acquire lock:
ffff88801f031908 (&sch->q.lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
ffff88801f031908 (&sch->q.lock){+...}-{2:2}, at: get_dist_table+0x1fa/0x2c0 net/sched/sch_netem.c:798

but task is already holding lock:
ffff88801f031908 (&sch->q.lock){+...}-{2:2}, at: netem_change+0x257/0x20c0 net/sched/sch_netem.c:972

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sch->q.lock);
  lock(&sch->q.lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz-executor313/3486:
 #0: ffffffff8d9e1148 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d9e1148 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x94c/0xee0 net/core/rtnetlink.c:5600
 #1: ffff88801f031908 (&sch->q.lock){+...}-{2:2}, at: netem_change+0x257/0x20c0 net/sched/sch_netem.c:972

stack backtrace:
CPU: 0 PID: 3486 Comm: syz-executor313 Tainted: G        W         5.15.126-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2946 [inline]
 check_deadlock kernel/locking/lockdep.c:2989 [inline]
 validate_chain+0x46cf/0x58b0 kernel/locking/lockdep.c:3774
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:368 [inline]
 get_dist_table+0x1fa/0x2c0 net/sched/sch_netem.c:798
 netem_change+0xa6a/0x20c0 net/sched/sch_netem.c:995
 netem_init+0x58/0xb0 net/sched/sch_netem.c:1075
 qdisc_create+0x8ae/0x1390 net/sched/sch_api.c:1264
 tc_modify_qdisc+0xac5/0x1710
 rtnetlink_rcv_msg+0x993/0xee0 net/core/rtnetlink.c:5603
 netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2505
 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
 netlink_unicast+0x7b6/0x980 net/netlink/af_netlink.c:1356
 netlink_sendmsg+0xa30/0xd60 net/netlink/af_netlink.c:1924
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
 __sys_sendmsg net/socket.c:2495 [inline]
 __do_sys_sendmsg net/socket.c:2504 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2502
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fe1e63214e9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff21504588 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fff21504758 RCX: 00007fe1e63214e9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 00007fe1e6394610 R08: 00000000ffffffff R09: 00007fff21504758
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff21504748 R14: 0000000000000001 R15: 0000000000000001
 </TASK>