======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.6997/2227 is trying to acquire lock:
ffffffff8ec848a0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline]
ffffffff8ec848a0 (fs_reclaim){+.+.}-{0:0}, at: prepare_alloc_pages+0x15b/0x650 mm/page_alloc.c:5048
but task is already holding lock:
ffff88807eaadcf8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:611 [inline]
ffff88807eaadcf8 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:441 [inline]
ffff88807eaadcf8 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x36/0x340 mm/mmap_lock.c:501
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (&mm->mmap_lock){++++}-{4:4}:
__might_fault+0xcb/0x130 mm/memory.c:7292
_inline_copy_from_user include/linux/uaccess.h:169 [inline]
_copy_from_user+0x28/0xb0 lib/usercopy.c:18
copy_from_user include/linux/uaccess.h:222 [inline]
csum_and_copy_from_user include/net/checksum.h:31 [inline]
copy_from_user_iter_csum net/core/skbuff.c:7451 [inline]
iterate_ubuf include/linux/iov_iter.h:30 [inline]
iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
csum_and_copy_from_iter_full+0x210/0x1fb0 net/core/skbuff.c:7463
ip_generic_getfrag+0x149/0x2d0 net/ipv4/ip_output.c:941
__ip6_append_data+0x3b26/0x40c0 net/ipv6/ip6_output.c:1732
ip6_append_data+0x108/0x270 net/ipv6/ip6_output.c:1887
rawv6_sendmsg+0x1298/0x18c0 net/ipv6/raw.c:913
sock_sendmsg_nosec+0x10e/0x180 net/socket.c:776
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmsg net/socket.c:2770 [inline]
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #6 (sk_lock-AF_INET6){+.+.}-{0:0}:
lock_sock_nested+0x41/0x100 net/core/sock.c:3828
lock_sock include/net/sock.h:1713 [inline]
inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:913
nbd_mark_nsock_dead+0x2cb/0x550 drivers/block/nbd.c:318
recv_work+0x1cee/0x1e10 drivers/block/nbd.c:1021
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #5 (&nsock->tx_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
nbd_queue_rq+0x373/0x1150 drivers/block/nbd.c:1207
blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2117
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
__blk_mq_sched_dispatch_requests+0xd36/0x1580 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_work_fn+0x16c/0x300 block/blk-mq.c:2532
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #4 (&cmd->lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
nbd_queue_rq+0xc1/0x1150 drivers/block/nbd.c:1199
blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2117
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
__blk_mq_sched_dispatch_requests+0xd36/0x1580 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_work_fn+0x16c/0x300 block/blk-mq.c:2532
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #3 (set->srcu){.+.+}-{0:0}:
srcu_lock_sync include/linux/srcu.h:199 [inline]
__synchronize_srcu+0xc9/0x2f0 kernel/rcu/srcutree.c:1481
elevator_switch+0x1e8/0x7b0 block/elevator.c:576
elevator_change+0x2fa/0x480 block/elevator.c:681
elevator_set_default+0x375/0x440 block/elevator.c:754
blk_register_queue+0x3f3/0x4e0 block/blk-sysfs.c:992
__add_disk+0x6cb/0xe30 block/genhd.c:524
add_disk_fwnode+0x100/0x3a0 block/genhd.c:593
add_disk include/linux/blkdev.h:800 [inline]
nbd_dev_add+0x733/0xb60 drivers/block/nbd.c:2021
nbd_init+0x15f/0x1e0 drivers/block/nbd.c:2729
do_one_initcall+0x250/0x870 init/main.c:1347
do_initcall_level+0x10a/0x1a0 init/main.c:1409
do_initcalls+0x59/0xa0 init/main.c:1425
kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
kernel_init+0x1d/0x1d0 init/main.c:1548
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #2 (&q->elevator_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821
elevator_change+0x1af/0x480 block/elevator.c:679
elevator_set_none+0xb5/0x140 block/elevator.c:769
blk_mq_elv_switch_none block/blk-mq.c:5101 [inline]
__blk_mq_update_nr_hw_queues block/blk-mq.c:5146 [inline]
blk_mq_update_nr_hw_queues+0x5ef/0x19f0 block/blk-mq.c:5211
nbd_start_device+0x189/0xb30 drivers/block/nbd.c:1526
nbd_genl_connect+0x1597/0x1c10 drivers/block/nbd.c:2276
genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmsg net/socket.c:2770 [inline]
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&q->q_usage_counter(io)#49){++++}-{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
nbd_dev_add+0x494/0xb60 drivers/block/nbd.c:1991
nbd_init+0x15f/0x1e0 drivers/block/nbd.c:2729
do_one_initcall+0x250/0x870 init/main.c:1347
do_initcall_level+0x10a/0x1a0 init/main.c:1409
do_initcalls+0x59/0xa0 init/main.c:1425
kernel_init_freeable+0x29d/0x3e0 init/main.c:1658
kernel_init+0x1d/0x1d0 init/main.c:1548
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:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4329 [inline]
fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4343
might_alloc include/linux/sched/mm.h:317 [inline]
prepare_alloc_pages+0x15b/0x650 mm/page_alloc.c:5048
__alloc_frozen_pages_noprof+0x12f/0x380 mm/page_alloc.c:5293
alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
pagetable_alloc_noprof include/linux/mm.h:3685 [inline]
__pud_alloc_one_noprof include/asm-generic/pgalloc.h:181 [inline]
pud_alloc_one_noprof include/asm-generic/pgalloc.h:206 [inline]
__pud_alloc+0x3a/0x460 mm/memory.c:6748
pud_alloc include/linux/mm.h:3595 [inline]
__handle_mm_fault mm/memory.c:6439 [inline]
handle_mm_fault+0x1f85/0x3080 mm/memory.c:6686
do_user_addr_fault+0x744/0x1340 arch/x86/mm/fault.c:1394
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
rep_movs_alternative+0x30/0xa0 arch/x86/lib/copy_user_64.S:53
copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
_inline_copy_from_user include/linux/uaccess.h:185 [inline]
_copy_from_user+0x7a/0xb0 lib/usercopy.c:18
copy_from_user include/linux/uaccess.h:222 [inline]
__rfcomm_release_dev net/bluetooth/rfcomm/tty.c:439 [inline]
rfcomm_release_dev net/bluetooth/rfcomm/tty.c:488 [inline]
rfcomm_dev_ioctl+0x1b4/0x21c0 net/bluetooth/rfcomm/tty.c:579
sock_do_ioctl+0x101/0x320 net/socket.c:1300
sock_ioctl+0x57a/0x7e0 net/socket.c:1421
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
fs_reclaim --> sk_lock-AF_INET6 --> &mm->mmap_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
rlock(&mm->mmap_lock);
lock(sk_lock-AF_INET6);
lock(&mm->mmap_lock);
lock(fs_reclaim);
*** DEADLOCK ***
2 locks held by syz.3.6997/2227:
#0: ffffffff901dbfe0 (rfcomm_ioctl_mutex){+.+.}-{4:4}, at: rfcomm_release_dev net/bluetooth/rfcomm/tty.c:487 [inline]
#0: ffffffff901dbfe0 (rfcomm_ioctl_mutex){+.+.}-{4:4}, at: rfcomm_dev_ioctl+0x187/0x21c0 net/bluetooth/rfcomm/tty.c:579
#1: ffff88807eaadcf8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_trylock include/linux/mmap_lock.h:611 [inline]
#1: ffff88807eaadcf8 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/mmap_lock.c:441 [inline]
#1: ffff88807eaadcf8 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x36/0x340 mm/mmap_lock.c:501
stack backtrace:
CPU: 1 UID: 0 PID: 2227 Comm: syz.3.6997 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4329 [inline]
fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4343
might_alloc include/linux/sched/mm.h:317 [inline]
prepare_alloc_pages+0x15b/0x650 mm/page_alloc.c:5048
__alloc_frozen_pages_noprof+0x12f/0x380 mm/page_alloc.c:5293
alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
pagetable_alloc_noprof include/linux/mm.h:3685 [inline]
__pud_alloc_one_noprof include/asm-generic/pgalloc.h:181 [inline]
pud_alloc_one_noprof include/asm-generic/pgalloc.h:206 [inline]
__pud_alloc+0x3a/0x460 mm/memory.c:6748
pud_alloc include/linux/mm.h:3595 [inline]
__handle_mm_fault mm/memory.c:6439 [inline]
handle_mm_fault+0x1f85/0x3080 mm/memory.c:6686
do_user_addr_fault+0x744/0x1340 arch/x86/mm/fault.c:1394
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0010:rep_movs_alternative+0x30/0xa0 arch/x86/lib/copy_user_64.S:60
Code: 83 f9 08 73 25 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 e9 cd 61 04 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 <48> 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 db 83 f9 08
RSP: 0018:ffffc90004447ab8 EFLAGS: 00050202
RAX: 00007ffffffff001 RBX: 0000000000000018 RCX: 0000000000000018
RDX: 0000000000000001 RSI: 0000200000000100 RDI: ffffc90004447bd0
RBP: ffffc90004447cb0 R08: ffffc90004447be7 R09: 1ffff92000888f7c
R10: dffffc0000000000 R11: fffff52000888f7d R12: ffff88803ac81000
R13: dffffc0000000000 R14: ffffc90004447bd0 R15: 0000200000000100
copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
raw_copy_from_user arch/x86/include/asm/uaccess_64.h:141 [inline]
_inline_copy_from_user include/linux/uaccess.h:185 [inline]
_copy_from_user+0x7a/0xb0 lib/usercopy.c:18
copy_from_user include/linux/uaccess.h:222 [inline]
__rfcomm_release_dev net/bluetooth/rfcomm/tty.c:439 [inline]
rfcomm_release_dev net/bluetooth/rfcomm/tty.c:488 [inline]
rfcomm_dev_ioctl+0x1b4/0x21c0 net/bluetooth/rfcomm/tty.c:579
sock_do_ioctl+0x101/0x320 net/socket.c:1300
sock_ioctl+0x57a/0x7e0 net/socket.c:1421
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3fd9f9de99
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:00007f3fdae88028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3fda225fa0 RCX: 00007f3fd9f9de99
RDX: 0000200000000100 RSI: 00000000400452c9 RDI: 0000000000000007
RBP: 00007f3fda033eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3fda226038 R14: 00007f3fda225fa0 R15: 00007ffda1a59dc8
tipc: Enabling of bearer rejected, failed to enable media
----------------
Code disassembly (best guess):
0: 83 f9 08 cmp $0x8,%ecx
3: 73 25 jae 0x2a
5: 85 c9 test %ecx,%ecx
7: 74 0f je 0x18
9: 8a 06 mov (%rsi),%al
b: 88 07 mov %al,(%rdi)
d: 48 ff c7 inc %rdi
10: 48 ff c6 inc %rsi
13: 48 ff c9 dec %rcx
16: 75 f1 jne 0x9
18: e9 cd 61 04 00 jmp 0x461ea
1d: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
24: 00 00 00
27: 0f 1f 00 nopl (%rax)
* 2a: 48 8b 06 mov (%rsi),%rax <-- trapping instruction
2d: 48 89 07 mov %rax,(%rdi)
30: 48 83 c6 08 add $0x8,%rsi
34: 48 83 c7 08 add $0x8,%rdi
38: 83 e9 08 sub $0x8,%ecx
3b: 74 db je 0x18
3d: 83 f9 08 cmp $0x8,%ecx