[v6.1] possible deadlock in net_tx_action

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Jun 28, 2023, 8:49:56 AM6/28/23

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Hello,

syzbot found the following issue on:

HEAD commit: a1c449d00ff8 Linux 6.1.36
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13ef25a8a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=18d0811d410fac65
dashboard link: https://syzkaller.appspot.com/bug?extid=47c0bb016be11e27f759
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1af4dd87a7c3/disk-a1c449d0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cb6c9d322fca/vmlinux-a1c449d0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cab3d4d89c94/bzImage-a1c449d0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47c0bb...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
6.1.36-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.4/14081 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffffffff8d0001e0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:271 [inline]
ffffffff8d0001e0 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710

and this task is already holding:
ffffffff8e0db448 (noop_qdisc.q.lock){+.-.}-{2:2}, at: netem_change+0x17e/0x1ea0 net/sched/sch_netem.c:969
which would create a new lock dependency:
(noop_qdisc.q.lock){+.-.}-{2:2} -> (fs_reclaim){+.+.}-{0:0}

but this new dependency connects a SOFTIRQ-irq-safe lock:
(noop_qdisc.q.lock){+.-.}-{2:2}

... which became SOFTIRQ-irq-safe at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
net_tx_action+0x752/0x970 net/core/dev.c:5077
__do_softirq+0x2e9/0xa4c kernel/softirq.c:571
do_softirq+0x162/0x240 kernel/softirq.c:472
__local_bh_enable_ip+0x1b1/0x1f0 kernel/softirq.c:396
netif_tx_unlock_bh include/linux/netdevice.h:4396 [inline]
dev_watchdog_down net/sched/sch_generic.c:566 [inline]
dev_deactivate_many+0x3b4/0xaf0 net/sched/sch_generic.c:1348
dev_deactivate+0x177/0x270 net/sched/sch_generic.c:1382
linkwatch_do_dev+0x104/0x160 net/core/link_watch.c:166
__linkwatch_run_queue+0x448/0x6b0 net/core/link_watch.c:221
linkwatch_event+0x48/0x50 net/core/link_watch.c:264
process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2289
worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

to a SOFTIRQ-irq-unsafe lock:
(fs_reclaim){+.+.}-{0:0}

... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1045
kmalloc include/linux/slab.h:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
alloc_workqueue_attrs+0x46/0xc0 kernel/workqueue.c:3394
wq_numa_init+0x122/0x4b0 kernel/workqueue.c:5959
workqueue_init+0x22/0x59d kernel/workqueue.c:6086
kernel_init_freeable+0x40a/0x61f init/main.c:1614
kernel_init+0x19/0x290 init/main.c:1519
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

other info that might help us debug this:

Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
local_irq_disable();
lock(noop_qdisc.q.lock);
lock(fs_reclaim);
<Interrupt>
lock(
noop_qdisc.q.lock);

*** DEADLOCK ***

2 locks held by syz-executor.4/14081:
#0: ffffffff8e094968 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffffffff8e094968 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x720/0xf00 net/core/rtnetlink.c:6094
#1: ffffffff8e0db448 (noop_qdisc.q.lock
){+.-.}-{2:2}, at: netem_change+0x17e/0x1ea0 net/sched/sch_netem.c:969

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (noop_qdisc.q.lock){+.-.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
__dev_xmit_skb net/core/dev.c:3854 [inline]
__dev_queue_xmit+0xd50/0x3c90 net/core/dev.c:4227
dev_queue_xmit include/linux/netdevice.h:3021 [inline]
tx+0x66/0x100 drivers/block/aoe/aoenet.c:63
kthread+0x234/0x440 drivers/block/aoe/aoecmd.c:1229
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
IN-SOFTIRQ-W at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
net_tx_action+0x752/0x970 net/core/dev.c:5077
__do_softirq+0x2e9/0xa4c kernel/softirq.c:571
do_softirq+0x162/0x240 kernel/softirq.c:472
__local_bh_enable_ip+0x1b1/0x1f0 kernel/softirq.c:396
netif_tx_unlock_bh include/linux/netdevice.h:4396 [inline]
dev_watchdog_down net/sched/sch_generic.c:566 [inline]
dev_deactivate_many+0x3b4/0xaf0 net/sched/sch_generic.c:1348
dev_deactivate+0x177/0x270 net/sched/sch_generic.c:1382
linkwatch_do_dev+0x104/0x160 net/core/link_watch.c:166
__linkwatch_run_queue+0x448/0x6b0 net/core/link_watch.c:221
linkwatch_event+0x48/0x50 net/core/link_watch.c:264
process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2289
worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
INITIAL USE at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
__dev_xmit_skb net/core/dev.c:3854 [inline]
__dev_queue_xmit+0xd50/0x3c90 net/core/dev.c:4227
dev_queue_xmit include/linux/netdevice.h:3021 [inline]
tx+0x66/0x100 drivers/block/aoe/aoenet.c:63
kthread+0x234/0x440 drivers/block/aoe/aoecmd.c:1229
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
}
... key at: [<ffffffff8e0db448>] noop_qdisc+0x108/0x320

the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (fs_reclaim){+.+.}-{0:0} {
HARDIRQ-ON-W at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1045
kmalloc include/linux/slab.h:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
alloc_workqueue_attrs+0x46/0xc0 kernel/workqueue.c:3394
wq_numa_init+0x122/0x4b0 kernel/workqueue.c:5959
workqueue_init+0x22/0x59d kernel/workqueue.c:6086
kernel_init_freeable+0x40a/0x61f init/main.c:1614
kernel_init+0x19/0x290 init/main.c:1519
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
SOFTIRQ-ON-W at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1045
kmalloc include/linux/slab.h:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
alloc_workqueue_attrs+0x46/0xc0 kernel/workqueue.c:3394
wq_numa_init+0x122/0x4b0 kernel/workqueue.c:5959
workqueue_init+0x22/0x59d kernel/workqueue.c:6086
kernel_init_freeable+0x40a/0x61f init/main.c:1614
kernel_init+0x19/0x290 init/main.c:1519
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
INITIAL USE at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1045
kmalloc include/linux/slab.h:553 [inline]
kzalloc include/linux/slab.h:689 [inline]
alloc_workqueue_attrs+0x46/0xc0 kernel/workqueue.c:3394
wq_numa_init+0x122/0x4b0 kernel/workqueue.c:5959
workqueue_init+0x22/0x59d kernel/workqueue.c:6086
kernel_init_freeable+0x40a/0x61f init/main.c:1614
kernel_init+0x19/0x290 init/main.c:1519
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
}
... key at: [<ffffffff8d0001e0>] __fs_reclaim_map+0x0/0xe0
... acquired at:
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xa2/0x230 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x6e/0x180 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0x91/0x380 net/sched/sch_netem.c:788
netem_change+0x947/0x1ea0 net/sched/sch_netem.c:985
netem_init+0x58/0xb0 net/sched/sch_netem.c:1072
qdisc_create+0x8a1/0x1220 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9e0/0x1da0 net/sched/sch_api.c:1723
rtnetlink_rcv_msg+0x776/0xf00 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2524
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x7bf/0x990 net/netlink/af_netlink.c:1354
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1902
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x59e/0x8f0 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x2a9/0x390 net/socket.c:2565
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+0x63/0xcd

stack backtrace:
CPU: 1 PID: 14081 Comm: syz-executor.4 Not tainted 6.1.36-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
print_bad_irq_dependency kernel/locking/lockdep.c:2612 [inline]
check_irq_usage kernel/locking/lockdep.c:2851 [inline]
check_prev_add kernel/locking/lockdep.c:3102 [inline]
check_prevs_add kernel/locking/lockdep.c:3217 [inline]
validate_chain+0x4d2e/0x58e0 kernel/locking/lockdep.c:3832
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook+0x2a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xa2/0x230 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x6e/0x180 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0x91/0x380 net/sched/sch_netem.c:788
netem_change+0x947/0x1ea0 net/sched/sch_netem.c:985
netem_init+0x58/0xb0 net/sched/sch_netem.c:1072
qdisc_create+0x8a1/0x1220 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9e0/0x1da0 net/sched/sch_api.c:1723
rtnetlink_rcv_msg+0x776/0xf00 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2524
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x7bf/0x990 net/netlink/af_netlink.c:1354
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1902
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x59e/0x8f0 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x2a9/0x390 net/socket.c:2565
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+0x63/0xcd
RIP: 0033:0x7fe85308c389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe853e7f168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe8531ac050 RCX: 00007fe85308c389
RDX: 0000000000000000 RSI: 0000000020001400 RDI: 0000000000000004
RBP: 00007fe8530d7493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd483a75ef R14: 00007fe853e7f300 R15: 0000000000022000
</TASK>
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:274
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 14081, name: syz-executor.4
preempt_count: 201, expected: 0
RCU nest depth: 0, expected: 0
INFO: lockdep is turned off.
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 PID: 14081 Comm: syz-executor.4 Not tainted 6.1.36-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
__might_resched+0x5cb/0x780 kernel/sched/core.c:9941
might_alloc include/linux/sched/mm.h:274 [inline]
slab_pre_alloc_hook+0x4a/0x2a0 mm/slab.h:710
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x47/0x260 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xa2/0x230 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x6e/0x180 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0x91/0x380 net/sched/sch_netem.c:788
netem_change+0x947/0x1ea0 net/sched/sch_netem.c:985
netem_init+0x58/0xb0 net/sched/sch_netem.c:1072
qdisc_create+0x8a1/0x1220 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9e0/0x1da0 net/sched/sch_api.c:1723
rtnetlink_rcv_msg+0x776/0xf00 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x1cd/0x410 net/netlink/af_netlink.c:2524
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x7bf/0x990 net/netlink/af_netlink.c:1354
netlink_sendmsg+0xa26/0xd60 net/netlink/af_netlink.c:1902
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x59e/0x8f0 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x2a9/0x390 net/socket.c:2565
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+0x63/0xcd
RIP: 0033:0x7fe85308c389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe853e7f168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe8531ac050 RCX: 00007fe85308c389
RDX: 0000000000000000 RSI: 0000000020001400 RDI: 0000000000000004
RBP: 00007fe8530d7493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd483a75ef R14: 00007fe853e7f300 R15: 0000000000022000
</TASK>

---
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syzbot

unread,

Jun 28, 2023, 11:25:05 PM6/28/23

to syzkaller...@googlegroups.com

Hello,

syzbot found the following issue on:

HEAD commit: 4af60700a60c Linux 5.15.119
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15aaacfb280000
kernel config: https://syzkaller.appspot.com/x/.config?x=f95d07036b0504a8
dashboard link: https://syzkaller.appspot.com/bug?extid=b5c172d26d856d563d2e

compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:

disk image: https://storage.googleapis.com/syzbot-assets/1a4abe225b30/disk-4af60700.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c57a50e7d39b/vmlinux-4af60700.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c21012530aba/Image-4af60700.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+b5c172...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected

5.15.119-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.5/8653 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffff800014b75540 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:206 [inline]
ffff800014b75540 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492

and this task is already holding:

ffff800016a16748 (noop_qdisc.q.lock){+.-.}-{2:2}, at: netem_change+0x22c/0x1a90 net/sched/sch_netem.c:972

which would create a new lock dependency:
(noop_qdisc.q.lock){+.-.}-{2:2} -> (fs_reclaim){+.+.}-{0:0}

but this new dependency connects a SOFTIRQ-irq-safe lock:
(noop_qdisc.q.lock){+.-.}-{2:2}

... which became SOFTIRQ-irq-safe at:

to a SOFTIRQ-irq-unsafe lock:
(fs_reclaim){+.+.}-{0:0}

... which became SOFTIRQ-irq-unsafe at:
...

other info that might help us debug this:

Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
local_irq_disable();
lock(noop_qdisc.q.lock);
lock(fs_reclaim);
<Interrupt>
lock(noop_qdisc.q.lock);

*** DEADLOCK ***

2 locks held by syz-executor.5/8653:
#0: ffff8000169d6ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffff8000169d6ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0xa2c/0xdac net/core/rtnetlink.c:5590
#1: ffff800016a16748 (noop_qdisc.q.lock){+.-.}-{2:2}, at: netem_change+0x22c/0x1a90 net/sched/sch_netem.c:972

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (noop_qdisc.q.lock){+.-.}-{2:2} {
HARDIRQ-ON-W at:

lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
__dev_xmit_skb net/core/dev.c:3848 [inline]
__dev_queue_xmit+0x8d0/0x2a6c net/core/dev.c:4190
dev_queue_xmit+0x24/0x34 net/core/dev.c:4258
tx+0x8c/0x130 drivers/block/aoe/aoenet.c:63
kthread+0x1ac/0x374 drivers/block/aoe/aoecmd.c:1230
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
IN-SOFTIRQ-W at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
net_tx_action+0x634/0x884 net/core/dev.c:5049
__do_softirq+0x344/0xe20 kernel/softirq.c:558
do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
do_softirq+0x120/0x20c kernel/softirq.c:459
__local_bh_enable_ip+0x2c0/0x4d0 kernel/softirq.c:383
local_bh_enable+0x28/0x174 include/linux/bottom_half.h:32
netif_tx_unlock_bh include/linux/netdevice.h:4545 [inline]
dev_watchdog_down net/sched/sch_generic.c:514 [inline]
dev_deactivate_many+0x580/0xbe4 net/sched/sch_generic.c:1302
dev_deactivate+0x13c/0x1fc net/sched/sch_generic.c:1336
linkwatch_do_dev+0x2a8/0x3c8 net/core/link_watch.c:165
__linkwatch_run_queue+0x424/0x730 net/core/link_watch.c:213
linkwatch_event+0x58/0x68 net/core/link_watch.c:252
process_one_work+0x790/0x11b8 kernel/workqueue.c:2307
worker_thread+0x910/0x1034 kernel/workqueue.c:2454
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
INITIAL USE at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
__dev_xmit_skb net/core/dev.c:3848 [inline]
__dev_queue_xmit+0x8d0/0x2a6c net/core/dev.c:4190
dev_queue_xmit+0x24/0x34 net/core/dev.c:4258
tx+0x8c/0x130 drivers/block/aoe/aoenet.c:63
kthread+0x1ac/0x374 drivers/block/aoe/aoecmd.c:1230
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
}
... key at: [<ffff800016a16748>] noop_qdisc+0x108/0x320

the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (fs_reclaim){+.+.}-{0:0} {
HARDIRQ-ON-W at:

lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
fs_reclaim_acquire+0xf0/0x1d0 mm/page_alloc.c:4561
might_alloc include/linux/sched/mm.h:206 [inline]
slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492
slab_alloc_node mm/slub.c:3134 [inline]
kmem_cache_alloc_node_trace+0xa0/0x4c4 mm/slub.c:3270
kmalloc_node include/linux/slab.h:609 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
alloc_worker kernel/workqueue.c:1858 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4276
workqueue_init+0x2b4/0x640 kernel/workqueue.c:6133
kernel_init_freeable+0x448/0x650 init/main.c:1603
kernel_init+0x24/0x294 init/main.c:1510
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
SOFTIRQ-ON-W at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
fs_reclaim_acquire+0xf0/0x1d0 mm/page_alloc.c:4561
might_alloc include/linux/sched/mm.h:206 [inline]
slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492
slab_alloc_node mm/slub.c:3134 [inline]
kmem_cache_alloc_node_trace+0xa0/0x4c4 mm/slub.c:3270
kmalloc_node include/linux/slab.h:609 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
alloc_worker kernel/workqueue.c:1858 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4276
workqueue_init+0x2b4/0x640 kernel/workqueue.c:6133
kernel_init_freeable+0x448/0x650 init/main.c:1603
kernel_init+0x24/0x294 init/main.c:1510
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
INITIAL USE at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
fs_reclaim_acquire+0xf0/0x1d0 mm/page_alloc.c:4561
might_alloc include/linux/sched/mm.h:206 [inline]
slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492
slab_alloc_node mm/slub.c:3134 [inline]
kmem_cache_alloc_node_trace+0xa0/0x4c4 mm/slub.c:3270
kmalloc_node include/linux/slab.h:609 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
alloc_worker kernel/workqueue.c:1858 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4276
workqueue_init+0x2b4/0x640 kernel/workqueue.c:6133
kernel_init_freeable+0x448/0x650 init/main.c:1603
kernel_init+0x24/0x294 init/main.c:1510
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
}
... key at: [<ffff800014b75540>] __fs_reclaim_map+0x0/0x200
... acquired at:
__fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
fs_reclaim_acquire+0xf0/0x1d0 mm/page_alloc.c:4561
might_alloc include/linux/sched/mm.h:206 [inline]
slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492
slab_alloc_node mm/slub.c:3134 [inline]
__kmalloc_node+0xbc/0x5b8 mm/slub.c:4451
kmalloc_node include/linux/slab.h:614 [inline]
kvmalloc_node+0x88/0x204 mm/util.c:619
kvmalloc include/linux/mm.h:805 [inline]
get_dist_table+0x9c/0x2a4 net/sched/sch_netem.c:788
netem_change+0x820/0x1a90 net/sched/sch_netem.c:995
netem_init+0x54/0xb8 net/sched/sch_netem.c:1075
qdisc_create+0x6fc/0xf44 net/sched/sch_api.c:1264
tc_modify_qdisc+0x8dc/0x1344
rtnetlink_rcv_msg+0xa74/0xdac net/core/rtnetlink.c:5593
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2504
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:5611
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x664/0x938 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x844/0xb38 net/netlink/af_netlink.c:1923
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
____sys_sendmsg+0x584/0x870 net/socket.c:2412
___sys_sendmsg+0x214/0x294 net/socket.c:2466
__sys_sendmsg net/socket.c:2495 [inline]
__do_sys_sendmsg net/socket.c:2504 [inline]
__se_sys_sendmsg net/socket.c:2502 [inline]
__arm64_sys_sendmsg+0x1ac/0x25c net/socket.c:2502
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

stack backtrace:
CPU: 1 PID: 8653 Comm: syz-executor.5 Not tainted 5.15.119-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
__lock_acquire+0x62b4/0x7620 kernel/locking/lockdep.c:5011
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
fs_reclaim_acquire+0xf0/0x1d0 mm/page_alloc.c:4561
might_alloc include/linux/sched/mm.h:206 [inline]
slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492
slab_alloc_node mm/slub.c:3134 [inline]
__kmalloc_node+0xbc/0x5b8 mm/slub.c:4451
kmalloc_node include/linux/slab.h:614 [inline]
kvmalloc_node+0x88/0x204 mm/util.c:619
kvmalloc include/linux/mm.h:805 [inline]
get_dist_table+0x9c/0x2a4 net/sched/sch_netem.c:788
netem_change+0x820/0x1a90 net/sched/sch_netem.c:995
netem_init+0x54/0xb8 net/sched/sch_netem.c:1075
qdisc_create+0x6fc/0xf44 net/sched/sch_api.c:1264
tc_modify_qdisc+0x8dc/0x1344
rtnetlink_rcv_msg+0xa74/0xdac net/core/rtnetlink.c:5593
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2504
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:5611
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x664/0x938 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x844/0xb38 net/netlink/af_netlink.c:1923
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
____sys_sendmsg+0x584/0x870 net/socket.c:2412
___sys_sendmsg+0x214/0x294 net/socket.c:2466
__sys_sendmsg net/socket.c:2495 [inline]
__do_sys_sendmsg net/socket.c:2504 [inline]
__se_sys_sendmsg net/socket.c:2502 [inline]
__arm64_sys_sendmsg+0x1ac/0x25c net/socket.c:2502
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:209
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 8653, name: syz-executor.5

INFO: lockdep is turned off.
Preemption disabled at:

[<ffff800010049c20>] netem_change+0x22c/0x1a90 net/sched/sch_netem.c:972
CPU: 1 PID: 8653 Comm: syz-executor.5 Not tainted 5.15.119-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
___might_sleep+0x380/0x4dc kernel/sched/core.c:9625
__might_sleep+0x98/0xf0 kernel/sched/core.c:9579
might_alloc include/linux/sched/mm.h:209 [inline]
slab_pre_alloc_hook+0x58/0xe8 mm/slab.h:492
slab_alloc_node mm/slub.c:3134 [inline]
__kmalloc_node+0xbc/0x5b8 mm/slub.c:4451
kmalloc_node include/linux/slab.h:614 [inline]
kvmalloc_node+0x88/0x204 mm/util.c:619
kvmalloc include/linux/mm.h:805 [inline]
get_dist_table+0x9c/0x2a4 net/sched/sch_netem.c:788
netem_change+0x820/0x1a90 net/sched/sch_netem.c:995
netem_init+0x54/0xb8 net/sched/sch_netem.c:1075
qdisc_create+0x6fc/0xf44 net/sched/sch_api.c:1264
tc_modify_qdisc+0x8dc/0x1344
rtnetlink_rcv_msg+0xa74/0xdac net/core/rtnetlink.c:5593
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2504
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:5611
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x664/0x938 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x844/0xb38 net/netlink/af_netlink.c:1923
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg net/socket.c:724 [inline]
____sys_sendmsg+0x584/0x870 net/socket.c:2412
___sys_sendmsg+0x214/0x294 net/socket.c:2466
__sys_sendmsg net/socket.c:2495 [inline]
__do_sys_sendmsg net/socket.c:2504 [inline]
__se_sys_sendmsg net/socket.c:2502 [inline]
__arm64_sys_sendmsg+0x1ac/0x25c net/socket.c:2502
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

syzbot

unread,

Jun 29, 2023, 12:50:00 AM6/29/23

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: a1c449d00ff8 Linux 6.1.36
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=13590ebf280000
kernel config: https://syzkaller.appspot.com/x/.config?x=88fba5343539f90e

dashboard link: https://syzkaller.appspot.com/bug?extid=47c0bb016be11e27f759
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a046cb280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16686280a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/46c419b02b39/disk-a1c449d0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cc8fc6c3c06c/vmlinux-a1c449d0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7ed5c1022bfe/Image-a1c449d0.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47c0bb...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
6.1.36-syzkaller #0 Not tainted
-----------------------------------------------------

syz-executor319/4218 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:271 [inline]
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slab.h:710 [inline]
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3318 [inline]
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: __kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437

and this task is already holding:

ffff800017bd3208 (noop_qdisc.q.lock){+.-.}-{2:2}, at: sch_tree_lock+0x120/0x1d4

lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
net_tx_action+0x6ec/0x94c net/core/dev.c:5077
__do_softirq+0x30c/0xea0 kernel/softirq.c:571
run_ksoftirqd+0x68/0x258 kernel/softirq.c:934
smpboot_thread_fn+0x4b0/0x96c kernel/smpboot.c:164
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

to a SOFTIRQ-irq-unsafe lock:
(fs_reclaim){+.+.}-{0:0}

... which became SOFTIRQ-irq-unsafe at:
...

2 locks held by syz-executor319/4218:
#0: ffff800017b8e848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffff800017b8e848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x6e8/0xd94 net/core/rtnetlink.c:6094
#1: ffff800017bd3208 (noop_qdisc.q.lock){+.-.}-{2:2}, at: sch_tree_lock+0x120/0x1d4

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (noop_qdisc.q.lock){+.-.}-{2:2} {
HARDIRQ-ON-W at:

lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154

spin_lock include/linux/spinlock.h:350 [inline]
__dev_xmit_skb net/core/dev.c:3854 [inline]

__dev_queue_xmit+0xb14/0x38d8 net/core/dev.c:4227
dev_queue_xmit include/linux/netdevice.h:3021 [inline]
tx+0x90/0x134 drivers/block/aoe/aoenet.c:63
kthread+0x1ac/0x374 drivers/block/aoe/aoecmd.c:1229
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
IN-SOFTIRQ-W at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
net_tx_action+0x6ec/0x94c net/core/dev.c:5077
__do_softirq+0x30c/0xea0 kernel/softirq.c:571
run_ksoftirqd+0x68/0x258 kernel/softirq.c:934
smpboot_thread_fn+0x4b0/0x96c kernel/smpboot.c:164
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
INITIAL USE at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154

spin_lock include/linux/spinlock.h:350 [inline]
__dev_xmit_skb net/core/dev.c:3854 [inline]

the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (fs_reclaim){+.+.}-{0:0} {
HARDIRQ-ON-W at:

lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
SOFTIRQ-ON-W at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
INITIAL USE at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
}
... key at: [<ffff80001585bd40>] __fs_reclaim_map+0x0/0xe0
... acquired at:
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xcc/0x1d0 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x84/0x1e4 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0xa0/0x354 net/sched/sch_netem.c:788
netem_change+0x754/0x1900 net/sched/sch_netem.c:985
netem_init+0x54/0xb8 net/sched/sch_netem.c:1072
qdisc_create+0x70c/0xe64 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9f0/0x1840
rtnetlink_rcv_msg+0x72c/0xd94 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2524
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6115
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1354
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1902

sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]

____sys_sendmsg+0x558/0x844 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x26c/0x33c net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

stack backtrace:
CPU: 0 PID: 4218 Comm: syz-executor319 Not tainted 6.1.36-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165

__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113

__lock_acquire+0x6310/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xcc/0x1d0 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x84/0x1e4 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0xa0/0x354 net/sched/sch_netem.c:788
netem_change+0x754/0x1900 net/sched/sch_netem.c:985
netem_init+0x54/0xb8 net/sched/sch_netem.c:1072
qdisc_create+0x70c/0xe64 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9f0/0x1840
rtnetlink_rcv_msg+0x72c/0xd94 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2524
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6115
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1354
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1902

sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]

BUG: sleeping function called from invalid context at include/linux/sched/mm.h:274

in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4218, name: syz-executor319

preempt_count: 201, expected: 0
RCU nest depth: 0, expected: 0
INFO: lockdep is turned off.
Preemption disabled at:

[<ffff8000106bed08>] sch_tree_lock+0x120/0x1d4
CPU: 0 PID: 4218 Comm: syz-executor319 Not tainted 6.1.36-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165

__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113

__might_resched+0x37c/0x4d8 kernel/sched/core.c:9941
__might_sleep+0x90/0xe4 kernel/sched/core.c:9870
might_alloc include/linux/sched/mm.h:274 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x74/0x388 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xcc/0x1d0 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x84/0x1e4 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0xa0/0x354 net/sched/sch_netem.c:788
netem_change+0x754/0x1900 net/sched/sch_netem.c:985
netem_init+0x54/0xb8 net/sched/sch_netem.c:1072
qdisc_create+0x70c/0xe64 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9f0/0x1840
rtnetlink_rcv_msg+0x72c/0xd94 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2524
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6115
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1354
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1902

sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]

____sys_sendmsg+0x558/0x844 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x26c/0x33c net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

syzbot

unread,

Jun 29, 2023, 1:16:00 AM6/29/23

to syzkaller...@googlegroups.com

syzbot has found a reproducer for the following issue on:

HEAD commit: 4af60700a60c Linux 5.15.119
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=17c95567280000

kernel config: https://syzkaller.appspot.com/x/.config?x=f95d07036b0504a8
dashboard link: https://syzkaller.appspot.com/bug?extid=b5c172d26d856d563d2e
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101e1577280000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16ac1270a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1a4abe225b30/disk-4af60700.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c57a50e7d39b/vmlinux-4af60700.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c21012530aba/Image-4af60700.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b5c172...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.15.119-syzkaller #0 Not tainted
-----------------------------------------------------

syz-executor393/3968 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:

ffff800014b75540 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:206 [inline]
ffff800014b75540 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook+0x38/0xe8 mm/slab.h:492

and this task is already holding:
ffff800016a16748 (noop_qdisc.q.lock){+.-.}-{2:2}, at: netem_change+0x22c/0x1a90 net/sched/sch_netem.c:972
which would create a new lock dependency:
(noop_qdisc.q.lock){+.-.}-{2:2} -> (fs_reclaim){+.+.}-{0:0}

but this new dependency connects a SOFTIRQ-irq-safe lock:
(noop_qdisc.q.lock){+.-.}-{2:2}

... which became SOFTIRQ-irq-safe at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
net_tx_action+0x634/0x884 net/core/dev.c:5049
__do_softirq+0x344/0xe20 kernel/softirq.c:558

run_ksoftirqd+0x68/0x258 kernel/softirq.c:920
smpboot_thread_fn+0x4b0/0x920 kernel/smpboot.c:164

2 locks held by syz-executor393/3968:

#0: ffff8000169d6ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffff8000169d6ea8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0xa2c/0xdac net/core/rtnetlink.c:5590
#1: ffff800016a16748 (noop_qdisc.q.lock){+.-.}-{2:2}, at: netem_change+0x22c/0x1a90 net/sched/sch_netem.c:972

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (noop_qdisc.q.lock){+.-.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
__dev_xmit_skb net/core/dev.c:3848 [inline]
__dev_queue_xmit+0x8d0/0x2a6c net/core/dev.c:4190
dev_queue_xmit+0x24/0x34 net/core/dev.c:4258
tx+0x8c/0x130 drivers/block/aoe/aoenet.c:63
kthread+0x1ac/0x374 drivers/block/aoe/aoecmd.c:1230
kthread+0x37c/0x45c kernel/kthread.c:319
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870
IN-SOFTIRQ-W at:
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
net_tx_action+0x634/0x884 net/core/dev.c:5049
__do_softirq+0x344/0xe20 kernel/softirq.c:558

run_ksoftirqd+0x68/0x258 kernel/softirq.c:920
smpboot_thread_fn+0x4b0/0x920 kernel/smpboot.c:164

CPU: 1 PID: 3968 Comm: syz-executor393 Not tainted 5.15.119-syzkaller #0

in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 3968, name: syz-executor393

INFO: lockdep is turned off.
Preemption disabled at:
[<ffff800010049c20>] netem_change+0x22c/0x1a90 net/sched/sch_netem.c:972

CPU: 1 PID: 3968 Comm: syz-executor393 Not tainted 5.15.119-syzkaller #0

syzbot

unread,

Aug 7, 2023, 12:56:24 AM8/7/23

to syzkaller...@googlegroups.com

syzbot suspects this issue could be fixed by backporting the following commit:

commit 29df86bbbad007eb1863c9d31473122c87c3e771
git tree: upstream
Author: Lad Prabhakar <prabhakar.ma...@bp.renesas.com>
Date: Mon Sep 19 09:21:30 2022 +0000

arm64: dts: renesas: rzg2lc-smarc: Include SoM DTSI into board DTS

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1120dd33a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=4242391d5bdd7a3a
dashboard link: https://syzkaller.appspot.com/bug?extid=47c0bb016be11e27f759
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1053d934a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15264780a80000

Please keep in mind that other backports might be required as well.

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

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