[syzbot] [net?] BUG: sleeping function called from invalid context in pcpu_alloc_noprof

[syzbot <syzbot+bcc12d6799364500fbec@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    836b313a14a3 ipv4: Honor "ignore_routes_with_linkdown" sys..
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11841a70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=734b5f968169d82b
dashboard link: https://syzkaller.appspot.com/bug?extid=bcc12d6799364500fbec
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=147be0f4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=127be0f4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8a23ff59cf08/disk-836b313a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/261168771da2/vmlinux-836b313a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5451cd746973/bzImage-836b313a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bcc12d6799364500fbec@syzkaller.appspotmail.com

IPv6: NLM_F_CREATE should be specified when creating new route
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:578
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 5829, name: syz-executor427
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
1 lock held by syz-executor427/5829:
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: ip6_route_add+0x4d/0x2f0 net/ipv6/route.c:3913
CPU: 0 UID: 0 PID: 5829 Comm: syz-executor427 Not tainted 6.15.0-rc4-syzkaller-00746-g836b313a14a3 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 __might_resched+0x495/0x610 kernel/sched/core.c:8818
 __mutex_lock_common kernel/locking/mutex.c:578 [inline]
 __mutex_lock+0x106/0xe80 kernel/locking/mutex.c:746
 pcpu_alloc_noprof+0x284/0x16b0 mm/percpu.c:1782
 dst_cache_init+0x37/0xc0 net/core/dst_cache.c:145
 ip_tun_build_state+0x193/0x6b0 net/ipv4/ip_tunnel_core.c:687
 lwtunnel_build_state+0x381/0x4c0 net/core/lwtunnel.c:137
 fib_nh_common_init+0x129/0x460 net/ipv4/fib_semantics.c:635
 fib6_nh_init+0x15e4/0x2030 net/ipv6/route.c:3669
 ip6_route_info_create_nh+0x139/0x870 net/ipv6/route.c:3866
 ip6_route_add+0xf6/0x2f0 net/ipv6/route.c:3915
 inet6_rtm_newroute+0x284/0x1c50 net/ipv6/route.c:5732
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x219/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe9b33468d9
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcf70e3268 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe9b33944ad RCX: 00007fe9b33468d9
RDX: 000000001000c840 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007fe9b339447d R08: 0000000000000000 R09: 0000555500000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe9b33943e5
R13: 0000000000000001 R14: 00007ffcf70e32b0 R15: 0000000000000003
 </TASK>

=============================
[ BUG: Invalid wait context ]
6.15.0-rc4-syzkaller-00746-g836b313a14a3 #0 Tainted: G        W          
-----------------------------
syz-executor427/5829 is trying to lock:
ffffffff8e021688 (pcpu_alloc_mutex){+.+.}-{4:4}, at: pcpu_alloc_noprof+0x284/0x16b0 mm/percpu.c:1782
other info that might help us debug this:
context-{5:5}
1 lock held by syz-executor427/5829:
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8df3b860 (rcu_read_lock){....}-{1:3}, at: ip6_route_add+0x4d/0x2f0 net/ipv6/route.c:3913
stack backtrace:
CPU: 0 UID: 0 PID: 5829 Comm: syz-executor427 Tainted: G        W           6.15.0-rc4-syzkaller-00746-g836b313a14a3 #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_lock_invalid_wait_context kernel/locking/lockdep.c:4831 [inline]
 check_wait_context kernel/locking/lockdep.c:4903 [inline]
 __lock_acquire+0xbcf/0xd20 kernel/locking/lockdep.c:5185
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866
 __mutex_lock_common kernel/locking/mutex.c:601 [inline]
 __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746
 pcpu_alloc_noprof+0x284/0x16b0 mm/percpu.c:1782
 dst_cache_init+0x37/0xc0 net/core/dst_cache.c:145
 ip_tun_build_state+0x193/0x6b0 net/ipv4/ip_tunnel_core.c:687
 lwtunnel_build_state+0x381/0x4c0 net/core/lwtunnel.c:137
 fib_nh_common_init+0x129/0x460 net/ipv4/fib_semantics.c:635
 fib6_nh_init+0x15e4/0x2030 net/ipv6/route.c:3669
 ip6_route_info_create_nh+0x139/0x870 net/ipv6/route.c:3866
 ip6_route_add+0xf6/0x2f0 net/ipv6/route.c:3915
 inet6_rtm_newroute+0x284/0x1c50 net/ipv6/route.c:5732
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x219/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe9b33468d9
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcf70e3268 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe9b33944ad RCX: 00007fe9b33468d9
RDX: 000000001000c840 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007fe9b339447d R08: 0000000000000000 R09: 0


---
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