======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
ksmd/37 is trying to acquire lock:
ffffffff8e645220 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:318 [inline]
ffffffff8e645220 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4896 [inline]
ffffffff8e645220 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:5220 [inline]
ffffffff8e645220 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc_noprof+0x45/0x6e0 mm/slub.c:5251
but task is already holding lock:
ffff888028ba01e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:368 [inline]
ffff888028ba01e0 (&mm->mmap_lock){++++}-{4:4}, at: scan_get_next_rmap_item mm/ksm.c:2532 [inline]
ffff888028ba01e0 (&mm->mmap_lock){++++}-{4:4}, at: ksm_do_scan+0x602/0x6540 mm/ksm.c:2659
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (&mm->mmap_lock){++++}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__might_fault+0xcc/0x130 mm/memory.c:7125
_copy_from_iter+0xf3/0x1790 lib/iov_iter.c:259
copy_from_iter include/linux/uio.h:228 [inline]
copy_from_iter_full include/linux/uio.h:245 [inline]
skb_do_copy_data_nocache include/net/sock.h:2269 [inline]
skb_copy_to_page_nocache include/net/sock.h:2295 [inline]
tcp_sendmsg_locked+0x2347/0x5540 net/ipv4/tcp.c:1272
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1413
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x19c/0x270 net/socket.c:729
sock_write_iter+0x279/0x360 net/socket.c:1182
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5c9/0xb30 fs/read_write.c:686
ksys_write+0x145/0x250 fs/read_write.c:738
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #6 (sk_lock-AF_INET){+.+.}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
lock_sock_nested+0x48/0x100 net/core/sock.c:3720
lock_sock include/net/sock.h:1679 [inline]
inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:907
nbd_mark_nsock_dead+0x2e9/0x560 drivers/block/nbd.c:318
sock_shutdown+0x15e/0x260 drivers/block/nbd.c:411
nbd_clear_sock drivers/block/nbd.c:1424 [inline]
nbd_config_put+0x342/0x790 drivers/block/nbd.c:1448
nbd_release+0xfe/0x140 drivers/block/nbd.c:1753
bdev_release+0x536/0x650 block/bdev.c:-1
blkdev_release+0x15/0x20 block/fops.c:702
__fput+0x44c/0xa70 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #5 (&nsock->tx_lock){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
nbd_handle_cmd drivers/block/nbd.c:1140 [inline]
nbd_queue_rq+0x257/0xf10 drivers/block/nbd.c:1204
blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2129
__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+0xda4/0x1570 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2367
blk_mq_dispatch_list+0xd0c/0xe00 include/linux/spinlock.h:-1
blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2976
__blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
__submit_bio+0x2d3/0x5a0 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x2fb/0xa50 block/blk-core.c:755
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x599/0x830 fs/buffer.c:2447
filemap_read_folio+0x117/0x380 mm/filemap.c:2444
do_read_cache_folio+0x350/0x590 mm/filemap.c:4009
read_mapping_folio include/linux/pagemap.h:999 [inline]
read_part_sector+0xb6/0x2b0 block/partitions/core.c:722
adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360
check_partition block/partitions/core.c:141 [inline]
blk_add_partitions block/partitions/core.c:589 [inline]
bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693
blkdev_get_whole+0x380/0x510 block/bdev.c:748
bdev_open+0x31e/0xd30 block/bdev.c:957
blkdev_open+0x457/0x600 block/fops.c:694
do_dentry_open+0x953/0x13f0 fs/open.c:965
vfs_open+0x3b/0x340 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x2ee5/0x3830 fs/namei.c:4134
do_filp_open+0x1fa/0x410 fs/namei.c:4161
do_sys_openat2+0x121/0x1c0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #4 (&cmd->lock){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
nbd_queue_rq+0xc8/0xf10 drivers/block/nbd.c:1196
blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2129
__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+0xda4/0x1570 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2367
blk_mq_dispatch_list+0xd0c/0xe00 include/linux/spinlock.h:-1
blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2976
__blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
__submit_bio+0x2d3/0x5a0 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x2fb/0xa50 block/blk-core.c:755
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x599/0x830 fs/buffer.c:2447
filemap_read_folio+0x117/0x380 mm/filemap.c:2444
do_read_cache_folio+0x350/0x590 mm/filemap.c:4009
read_mapping_folio include/linux/pagemap.h:999 [inline]
read_part_sector+0xb6/0x2b0 block/partitions/core.c:722
adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360
check_partition block/partitions/core.c:141 [inline]
blk_add_partitions block/partitions/core.c:589 [inline]
bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693
blkdev_get_whole+0x380/0x510 block/bdev.c:748
bdev_open+0x31e/0xd30 block/bdev.c:957
blkdev_open+0x457/0x600 block/fops.c:694
do_dentry_open+0x953/0x13f0 fs/open.c:965
vfs_open+0x3b/0x340 fs/open.c:1097
do_open fs/namei.c:3975 [inline]
path_openat+0x2ee5/0x3830 fs/namei.c:4134
do_filp_open+0x1fa/0x410 fs/namei.c:4161
do_sys_openat2+0x121/0x1c0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (set->srcu){.+.+}-{0:0}:
lock_sync+0xba/0x160 kernel/locking/lockdep.c:5916
srcu_lock_sync include/linux/srcu.h:173 [inline]
__synchronize_srcu+0x96/0x3a0 kernel/rcu/srcutree.c:1429
elevator_switch+0x12b/0x640 block/elevator.c:588
elevator_change+0x315/0x4c0 block/elevator.c:691
elevator_set_default+0x186/0x260 block/elevator.c:767
blk_register_queue+0x34e/0x3f0 block/blk-sysfs.c:942
__add_disk+0x677/0xd50 block/genhd.c:528
add_disk_fwnode+0xfc/0x480 block/genhd.c:597
add_disk include/linux/blkdev.h:775 [inline]
nbd_dev_add+0x717/0xae0 drivers/block/nbd.c:1981
nbd_init+0x168/0x1f0 drivers/block/nbd.c:2688
do_one_initcall+0x236/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
kernel_init_freeable+0x334/0x4b0 init/main.c:1593
kernel_init+0x1d/0x1d0 init/main.c:1483
ret_from_fork+0x4bc/0x870 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}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
elevator_change+0x1e5/0x4c0 block/elevator.c:689
elevator_set_none+0x42/0xb0 block/elevator.c:782
blk_mq_elv_switch_none block/blk-mq.c:5032 [inline]
__blk_mq_update_nr_hw_queues block/blk-mq.c:5075 [inline]
blk_mq_update_nr_hw_queues+0x598/0x1ab0 block/blk-mq.c:5133
nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1486
nbd_genl_connect+0x135b/0x18f0 drivers/block/nbd.c:2236
genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:729
____sys_sendmsg+0x505/0x830 net/socket.c:2617
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2671
__sys_sendmsg net/socket.c:2703 [inline]
__do_sys_sendmsg net/socket.c:2708 [inline]
__se_sys_sendmsg net/socket.c:2706 [inline]
__x64_sys_sendmsg+0x19b/0x260 net/socket.c:2706
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&q->q_usage_counter(io)#49){++++}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
blk_alloc_queue+0x538/0x620 block/blk-core.c:461
blk_mq_alloc_queue block/blk-mq.c:4399 [inline]
__blk_mq_alloc_disk+0x15c/0x340 block/blk-mq.c:4446
nbd_dev_add+0x46c/0xae0 drivers/block/nbd.c:1951
nbd_init+0x168/0x1f0 drivers/block/nbd.c:2688
do_one_initcall+0x236/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
kernel_init_freeable+0x334/0x4b0 init/main.c:1593
kernel_init+0x1d/0x1d0 init/main.c:1483
ret_from_fork+0x4bc/0x870 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4283
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4896 [inline]
slab_alloc_node mm/slub.c:5220 [inline]
kmem_cache_alloc_noprof+0x45/0x6e0 mm/slub.c:5251
alloc_rmap_item mm/ksm.c:565 [inline]
get_next_rmap_item mm/ksm.c:2378 [inline]
scan_get_next_rmap_item mm/ksm.c:2565 [inline]
ksm_do_scan+0xbaf/0x6540 mm/ksm.c:2659
ksm_scan_thread+0x10b/0x4b0 mm/ksm.c:2684
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
other info that might help us debug this:
Chain exists of:
fs_reclaim --> sk_lock-AF_INET --> &mm->mmap_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
rlock(&mm->mmap_lock);
lock(sk_lock-AF_INET);
lock(&mm->mmap_lock);
lock(fs_reclaim);
*** DEADLOCK ***
2 locks held by ksmd/37:
#0: ffffffff8e659188 (ksm_thread_mutex){+.+.}-{4:4}, at: ksm_scan_thread+0xc8/0x4b0 mm/ksm.c:2681
#1: ffff888028ba01e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:368 [inline]
#1: ffff888028ba01e0 (&mm->mmap_lock){++++}-{4:4}, at: scan_get_next_rmap_item mm/ksm.c:2532 [inline]
#1: ffff888028ba01e0 (&mm->mmap_lock){++++}-{4:4}, at: ksm_do_scan+0x602/0x6540 mm/ksm.c:2659
stack backtrace:
CPU: 1 UID: 0 PID: 37 Comm: ksmd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4283
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4896 [inline]
slab_alloc_node mm/slub.c:5220 [inline]
kmem_cache_alloc_noprof+0x45/0x6e0 mm/slub.c:5251
alloc_rmap_item mm/ksm.c:565 [inline]
get_next_rmap_item mm/ksm.c:2378 [inline]
scan_get_next_rmap_item mm/ksm.c:2565 [inline]
ksm_do_scan+0xbaf/0x6540 mm/ksm.c:2659
ksm_scan_thread+0x10b/0x4b0 mm/ksm.c:2684
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>