On Mon, 29 Sep 2025 14:46:29 -0700 syzbot <[email protected]> wrote:
> Hello, > > syzbot found the following issue on: > > HEAD commit: bf40f4b87761 Merge tag 'probes-fixes-v6.17-rc7' of git://g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=11161142580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=595e5938a1dd5b4e > dashboard link: https://syzkaller.appspot.com/bug?extid=c530b4d95ec5cd4f33a7 > compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils > for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. Of course not, as I believe it has to do with another fault injection. Just before this triggered, there's this: [ 494.628607][T14281] mmap: syz.4.2040 (14281) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst. [ 494.897085][T14287] block nbd9: NBD_DISCONNECT [ 494.915292][T14285] CIFS: VFS: Invalid SecurityFlags: [ 495.594680][T14300] ima: policy update failed [ 495.617068][ T30] audit: type=1802 audit(1758836743.046:78): pid=14300 uid=0 auid=4294967295 ses=4294967295 subj=unconfined op=policy_update cause=failed comm="syz.3.2043" res=0 errno=0 [ 496.169087][T14325] ICMPv6: process `syz.3.2057' is using deprecated sysctl (syscall) net.ipv6.neigh.ipvlan1.retrans_time - use net.ipv6.neigh.ipvlan1.retrans_time_ms instead [ 496.275995][T14330] FAULT_INJECTION: forcing a failure. [ 496.275995][T14330] name failslab, interval 1, probability 0, space 0, times 0 [ 496.330968][T14330] CPU: 1 UID: 0 PID: 14330 Comm: syz.2.2059 Tainted: G U syzkaller #0 PREEMPT(full) [ 496.331008][T14330] Tainted: [U]=USER [ 496.331015][T14330] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 [ 496.331027][T14330] Call Trace: [ 496.331035][T14330] <TASK> [ 496.331043][T14330] dump_stack_lvl+0x16c/0x1f0 [ 496.331081][T14330] should_fail_ex+0x512/0x640 [ 496.331113][T14330] ? kmem_cache_alloc_noprof+0x5a/0x3b0 [ 496.331143][T14330] should_failslab+0xc2/0x120 [ 496.331173][T14330] kmem_cache_alloc_noprof+0x6d/0x3b0 [ 496.331202][T14330] ? vma_merge_new_range+0x3ae/0xa50 [ 496.331227][T14330] ? vm_area_alloc+0x1f/0x160 [ 496.331256][T14330] vm_area_alloc+0x1f/0x160 [ 496.331278][T14330] __mmap_region+0xf90/0x27b0 [ 496.331305][T14330] ? __pfx___mmap_region+0x10/0x10 [ 496.331340][T14330] ? is_bpf_text_address+0x8a/0x1a0 [ 496.331368][T14330] ? bpf_ksym_find+0x124/0x1c0 [ 496.331391][T14330] ? __pfx_stack_trace_consume_entry+0x10/0x10 [ 496.331420][T14330] ? is_bpf_text_address+0x94/0x1a0 [ 496.331448][T14330] ? kernel_text_address+0x8d/0x100 [ 496.331470][T14330] ? __kernel_text_address+0xd/0x40 [ 496.331557][T14330] ? trace_cap_capable+0x18d/0x200 [ 496.331596][T14330] mmap_region+0x1ab/0x3f0 [ 496.331625][T14330] ? __get_unmapped_area+0x267/0x440 [ 496.331662][T14330] do_mmap+0xa3e/0x1210 [ 496.331701][T14330] ? __pfx_do_mmap+0x10/0x10 [ 496.331733][T14330] ? __pfx_down_write_killable+0x10/0x10 [ 496.331763][T14330] vm_mmap_pgoff+0x29e/0x470 [ 496.331801][T14330] ? __pfx_vm_mmap_pgoff+0x10/0x10 [ 496.331833][T14330] ? __fget_files+0x20e/0x3c0 [ 496.331868][T14330] ksys_mmap_pgoff+0x7d/0x5c0 [ 496.331899][T14330] ? __pfx_ksys_write+0x10/0x10 [ 496.331931][T14330] __x64_sys_mmap+0x125/0x190 [ 496.331974][T14333] block nbd9: NBD_DISCONNECT [ 496.331967][T14330] do_syscall_64+0xcd/0x4c0 [ 496.332004][T14330] entry_SYSCALL_64_after_hwframe+0x77/0x7f I wonder if this leaked a cpu read lock or something to trigger the lockdep bug later on? -- Steve > > Downloadable assets: > disk image: > https://storage.googleapis.com/syzbot-assets/14d0f00fdd13/disk-bf40f4b8.raw.xz > vmlinux: > https://storage.googleapis.com/syzbot-assets/28a0a02e6595/vmlinux-bf40f4b8.xz > kernel image: > https://storage.googleapis.com/syzbot-assets/5cd55b81a693/bzImage-bf40f4b8.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: [email protected] > > ====================================================== > WARNING: possible circular locking dependency detected > syzkaller #0 Tainted: G U > ------------------------------------------------------ > syz.0.2065/14355 is trying to acquire lock: > ffff88801b880488 (&buffer->mutex#2){+.+.}-{4:4}, at: class_mutex_constructor > include/linux/mutex.h:228 [inline] > ffff88801b880488 (&buffer->mutex#2){+.+.}-{4:4}, at: > ring_buffer_map+0x145/0xcc0 kernel/trace/ring_buffer.c:7238 > > but task is already holding lock: > ffff88801b8889f8 (&cpu_buffer->mapping_lock){+.+.}-{4:4}, at: > class_mutex_constructor include/linux/mutex.h:228 [inline] > ffff88801b8889f8 (&cpu_buffer->mapping_lock){+.+.}-{4:4}, at: > ring_buffer_map+0xdf/0xcc0 kernel/trace/ring_buffer.c:7228 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #9 (&cpu_buffer->mapping_lock){+.+.}-{4:4}: > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 > class_mutex_constructor include/linux/mutex.h:228 [inline] > ring_buffer_map+0xdf/0xcc0 kernel/trace/ring_buffer.c:7228 > tracing_buffers_mmap+0x120/0x1c0 kernel/trace/trace.c:8626 > vfs_mmap include/linux/fs.h:2290 [inline] > mmap_file mm/internal.h:167 [inline] > __mmap_new_file_vma mm/vma.c:2413 [inline] > __mmap_new_vma mm/vma.c:2476 [inline] > __mmap_region+0x1314/0x27b0 mm/vma.c:2669 > mmap_region+0x1ab/0x3f0 mm/vma.c:2739 > do_mmap+0xa3e/0x1210 mm/mmap.c:558 > vm_mmap_pgoff+0x29e/0x470 mm/util.c:580 > ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604 > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] > __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #8 (&mm->mmap_lock){++++}-{4:4}: > __might_fault mm/memory.c:6958 [inline] > __might_fault+0x113/0x190 mm/memory.c:6952 > _inline_copy_from_user include/linux/uaccess.h:162 [inline] > _copy_from_user+0x29/0xd0 lib/usercopy.c:18 > copy_from_user include/linux/uaccess.h:212 [inline] > csum_and_copy_from_user include/net/checksum.h:31 [inline] > copy_from_user_iter_csum net/core/skbuff.c:7323 [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+0x21a/0x1f90 net/core/skbuff.c:7335 > ip_generic_getfrag+0x170/0x270 net/ipv4/ip_output.c:940 > raw6_getfrag+0x22d/0x2a0 net/ipv6/raw.c:737 > __ip6_append_data+0x3e1b/0x4750 net/ipv6/ip6_output.c:1706 > ip6_append_data+0x1bd/0x4c0 net/ipv6/ip6_output.c:1860 > rawv6_sendmsg+0x163d/0x4820 net/ipv6/raw.c:911 > inet_sendmsg+0x11c/0x140 net/ipv4/af_inet.c:851 > sock_sendmsg_nosec net/socket.c:714 [inline] > __sock_sendmsg net/socket.c:729 [inline] > ____sys_sendmsg+0x973/0xc70 net/socket.c:2614 > ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 > __sys_sendmsg+0x16d/0x220 net/socket.c:2700 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #7 (sk_lock-AF_INET6){+.+.}-{0:0}: > lock_sock_nested+0x41/0xf0 net/core/sock.c:3711 > lock_sock include/net/sock.h:1669 [inline] > inet_autobind+0x1a/0x1a0 net/ipv4/af_inet.c:178 > inet_send_prepare+0x31b/0x530 net/ipv4/af_inet.c:837 > inet_sendmsg+0x43/0x140 net/ipv4/af_inet.c:848 > sock_sendmsg_nosec net/socket.c:714 [inline] > __sock_sendmsg net/socket.c:729 [inline] > sock_sendmsg+0x37f/0x470 net/socket.c:752 > __sock_xmit+0x1e7/0x4f0 drivers/block/nbd.c:574 > sock_xmit drivers/block/nbd.c:602 [inline] > send_disconnects drivers/block/nbd.c:1395 [inline] > nbd_disconnect+0x392/0x550 drivers/block/nbd.c:1410 > nbd_disconnect_and_put+0x2e/0x1c0 drivers/block/nbd.c:2245 > nbd_genl_disconnect+0x396/0x570 drivers/block/nbd.c:2291 > genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115 > genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] > genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210 > netlink_rcv_skb+0x158/0x420 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+0x5a7/0x870 net/netlink/af_netlink.c:1346 > netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896 > sock_sendmsg_nosec net/socket.c:714 [inline] > __sock_sendmsg net/socket.c:729 [inline] > ____sys_sendmsg+0xa98/0xc70 net/socket.c:2614 > ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668 > __sys_sendmsg+0x16d/0x220 net/socket.c:2700 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #6 (&nsock->tx_lock){+.+.}-{4:4}: > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 > nbd_handle_cmd drivers/block/nbd.c:1140 [inline] > nbd_queue_rq+0x423/0x12d0 drivers/block/nbd.c:1204 > blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2120 > __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+0xcb7/0x15f0 block/blk-mq-sched.c:307 > blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329 > blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2358 > blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2919 > blk_mq_flush_plug_list block/blk-mq.c:2967 [inline] > blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2939 > __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1220 > blk_finish_plug block/blk-core.c:1247 [inline] > blk_finish_plug block/blk-core.c:1244 [inline] > __submit_bio+0x545/0x690 block/blk-core.c:649 > __submit_bio_noacct_mq block/blk-core.c:722 [inline] > submit_bio_noacct_nocheck+0x660/0xd30 block/blk-core.c:751 > submit_bio_noacct+0xc20/0x1ed0 block/blk-core.c:874 > submit_bh fs/buffer.c:2829 [inline] > block_read_full_folio+0x4db/0x850 fs/buffer.c:2461 > filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2413 > do_read_cache_folio+0x263/0x5c0 mm/filemap.c:3957 > read_mapping_folio include/linux/pagemap.h:991 [inline] > read_part_sector+0xd4/0x370 block/partitions/core.c:722 > adfspart_check_ICS+0x93/0x940 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+0x720/0x1520 block/partitions/core.c:693 > blkdev_get_whole+0x187/0x290 block/bdev.c:748 > bdev_open+0x2c7/0xe40 block/bdev.c:957 > blkdev_open+0x34e/0x4f0 block/fops.c:694 > do_dentry_open+0x982/0x1530 fs/open.c:965 > vfs_open+0x82/0x3f0 fs/open.c:1095 > do_open fs/namei.c:3887 [inline] > path_openat+0x1de4/0x2cb0 fs/namei.c:4046 > do_filp_open+0x20b/0x470 fs/namei.c:4073 > do_sys_openat2+0x11b/0x1d0 fs/open.c:1435 > do_sys_open fs/open.c:1450 [inline] > __do_sys_openat fs/open.c:1466 [inline] > __se_sys_openat fs/open.c:1461 [inline] > __x64_sys_openat+0x174/0x210 fs/open.c:1461 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #5 (&cmd->lock){+.+.}-{4:4}: > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 > nbd_queue_rq+0xbd/0x12d0 drivers/block/nbd.c:1196 > blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2120 > __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+0xcb7/0x15f0 block/blk-mq-sched.c:307 > blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329 > blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2358 > blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2919 > blk_mq_flush_plug_list block/blk-mq.c:2967 [inline] > blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2939 > __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1220 > blk_finish_plug block/blk-core.c:1247 [inline] > blk_finish_plug block/blk-core.c:1244 [inline] > __submit_bio+0x545/0x690 block/blk-core.c:649 > __submit_bio_noacct_mq block/blk-core.c:722 [inline] > submit_bio_noacct_nocheck+0x660/0xd30 block/blk-core.c:751 > submit_bio_noacct+0xc20/0x1ed0 block/blk-core.c:874 > submit_bh fs/buffer.c:2829 [inline] > block_read_full_folio+0x4db/0x850 fs/buffer.c:2461 > filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2413 > do_read_cache_folio+0x263/0x5c0 mm/filemap.c:3957 > read_mapping_folio include/linux/pagemap.h:991 [inline] > read_part_sector+0xd4/0x370 block/partitions/core.c:722 > adfspart_check_ICS+0x93/0x940 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+0x720/0x1520 block/partitions/core.c:693 > blkdev_get_whole+0x187/0x290 block/bdev.c:748 > bdev_open+0x2c7/0xe40 block/bdev.c:957 > blkdev_open+0x34e/0x4f0 block/fops.c:694 > do_dentry_open+0x982/0x1530 fs/open.c:965 > vfs_open+0x82/0x3f0 fs/open.c:1095 > do_open fs/namei.c:3887 [inline] > path_openat+0x1de4/0x2cb0 fs/namei.c:4046 > do_filp_open+0x20b/0x470 fs/namei.c:4073 > do_sys_openat2+0x11b/0x1d0 fs/open.c:1435 > do_sys_open fs/open.c:1450 [inline] > __do_sys_openat fs/open.c:1466 [inline] > __se_sys_openat fs/open.c:1461 [inline] > __x64_sys_openat+0x174/0x210 fs/open.c:1461 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #4 (set->srcu){.+.+}-{0:0}: > srcu_lock_sync include/linux/srcu.h:173 [inline] > __synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1429 > blk_mq_wait_quiesce_done block/blk-mq.c:283 [inline] > blk_mq_wait_quiesce_done block/blk-mq.c:280 [inline] > blk_mq_quiesce_queue block/blk-mq.c:303 [inline] > blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:298 > elevator_switch+0x17d/0x810 block/elevator.c:588 > elevator_change+0x391/0x580 block/elevator.c:690 > elevator_set_default+0x2e9/0x380 block/elevator.c:766 > blk_register_queue+0x384/0x4e0 block/blk-sysfs.c:904 > __add_disk+0x74a/0xf00 block/genhd.c:528 > add_disk_fwnode+0x13f/0x5d0 block/genhd.c:597 > add_disk include/linux/blkdev.h:774 [inline] > nbd_dev_add+0x783/0xbb0 drivers/block/nbd.c:1973 > nbd_init+0x181/0x320 drivers/block/nbd.c:2680 > do_one_initcall+0x120/0x6e0 init/main.c:1269 > do_initcall_level init/main.c:1331 [inline] > do_initcalls init/main.c:1347 [inline] > do_basic_setup init/main.c:1366 [inline] > kernel_init_freeable+0x5c2/0x910 init/main.c:1579 > kernel_init+0x1c/0x2b0 init/main.c:1469 > ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > -> #3 (&q->elevator_lock){+.+.}-{4:4}: > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 > queue_requests_store+0x1c7/0x310 block/blk-sysfs.c:80 > queue_attr_store+0x26b/0x310 block/blk-sysfs.c:831 > sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 > kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352 > new_sync_write fs/read_write.c:593 [inline] > vfs_write+0x7d0/0x11d0 fs/read_write.c:686 > ksys_write+0x12a/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #2 (&q->q_usage_counter(io)#61){++++}-{0:0}: > blk_alloc_queue+0x619/0x760 block/blk-core.c:461 > blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4400 > __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4447 > nbd_dev_add+0x492/0xbb0 drivers/block/nbd.c:1943 > nbd_init+0x181/0x320 drivers/block/nbd.c:2680 > do_one_initcall+0x120/0x6e0 init/main.c:1269 > do_initcall_level init/main.c:1331 [inline] > do_initcalls init/main.c:1347 [inline] > do_basic_setup init/main.c:1366 [inline] > kernel_init_freeable+0x5c2/0x910 init/main.c:1579 > kernel_init+0x1c/0x2b0 init/main.c:1469 > ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > -> #1 (fs_reclaim){+.+.}-{0:0}: > __fs_reclaim_acquire mm/page_alloc.c:4234 [inline] > fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4248 > might_alloc include/linux/sched/mm.h:318 [inline] > slab_pre_alloc_hook mm/slub.c:4142 [inline] > slab_alloc_node mm/slub.c:4220 [inline] > __do_kmalloc_node mm/slub.c:4375 [inline] > __kmalloc_node_noprof+0xbe/0x500 mm/slub.c:4382 > kmalloc_node_noprof include/linux/slab.h:932 [inline] > __rb_allocate_pages+0x4b8/0xeb0 kernel/trace/ring_buffer.c:2246 > ring_buffer_resize+0x71a/0x15c0 kernel/trace/ring_buffer.c:2986 > __tracing_resize_ring_buffer kernel/trace/trace.c:5987 [inline] > __tracing_resize_ring_buffer kernel/trace/trace.c:5968 [inline] > tracing_update_buffers+0x15e/0x1f0 kernel/trace/trace.c:6219 > ftrace_event_write+0x14a/0x2c0 kernel/trace/trace_events.c:1506 > vfs_write+0x2a0/0x11d0 fs/read_write.c:684 > ksys_write+0x12a/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #0 (&buffer->mutex#2){+.+.}-{4:4}: > 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 > lock_acquire kernel/locking/lockdep.c:5868 [inline] > lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 > class_mutex_constructor include/linux/mutex.h:228 [inline] > ring_buffer_map+0x145/0xcc0 kernel/trace/ring_buffer.c:7238 > tracing_buffers_mmap+0x120/0x1c0 kernel/trace/trace.c:8626 > vfs_mmap include/linux/fs.h:2290 [inline] > mmap_file mm/internal.h:167 [inline] > __mmap_new_file_vma mm/vma.c:2413 [inline] > __mmap_new_vma mm/vma.c:2476 [inline] > __mmap_region+0x1314/0x27b0 mm/vma.c:2669 > mmap_region+0x1ab/0x3f0 mm/vma.c:2739 > do_mmap+0xa3e/0x1210 mm/mmap.c:558 > vm_mmap_pgoff+0x29e/0x470 mm/util.c:580 > ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604 > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] > __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 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: > &buffer->mutex#2 --> &mm->mmap_lock --> &cpu_buffer->mapping_lock > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&cpu_buffer->mapping_lock); > lock(&mm->mmap_lock); > lock(&cpu_buffer->mapping_lock); > lock(&buffer->mutex#2); > > *** DEADLOCK *** > > 2 locks held by syz.0.2065/14355: > #0: ffff88802cc2c260 (&mm->mmap_lock){++++}-{4:4}, at: > mmap_write_lock_killable include/linux/mmap_lock.h:415 [inline] > #0: ffff88802cc2c260 (&mm->mmap_lock){++++}-{4:4}, at: > vm_mmap_pgoff+0x1f5/0x470 mm/util.c:578 > #1: ffff88801b8889f8 (&cpu_buffer->mapping_lock){+.+.}-{4:4}, at: > class_mutex_constructor include/linux/mutex.h:228 [inline] > #1: ffff88801b8889f8 (&cpu_buffer->mapping_lock){+.+.}-{4:4}, at: > ring_buffer_map+0xdf/0xcc0 kernel/trace/ring_buffer.c:7228 > > stack backtrace: > CPU: 0 UID: 0 PID: 14355 Comm: syz.0.2065 Tainted: G U > syzkaller #0 PREEMPT(full) > Tainted: [U]=USER > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 08/18/2025 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 > print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2043 > check_noncircular+0x14c/0x170 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+0x12a6/0x1ce0 kernel/locking/lockdep.c:5237 > lock_acquire kernel/locking/lockdep.c:5868 [inline] > lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 > class_mutex_constructor include/linux/mutex.h:228 [inline] > ring_buffer_map+0x145/0xcc0 kernel/trace/ring_buffer.c:7238 > tracing_buffers_mmap+0x120/0x1c0 kernel/trace/trace.c:8626 > vfs_mmap include/linux/fs.h:2290 [inline] > mmap_file mm/internal.h:167 [inline] > __mmap_new_file_vma mm/vma.c:2413 [inline] > __mmap_new_vma mm/vma.c:2476 [inline] > __mmap_region+0x1314/0x27b0 mm/vma.c:2669 > mmap_region+0x1ab/0x3f0 mm/vma.c:2739 > do_mmap+0xa3e/0x1210 mm/mmap.c:558 > vm_mmap_pgoff+0x29e/0x470 mm/util.c:580 > ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:604 > __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] > __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] > __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f2640f8eec9 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f2641d8d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 > RAX: ffffffffffffffda RBX: 00007f26411e5fa0 RCX: 00007f2640f8eec9 > RDX: 0000000000000001 RSI: 0000000000004000 RDI: 0000200000ffc000 > RBP: 00007f2641011f91 R08: 0000000000000003 R09: 0000000000000000 > R10: 000000000008e051 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f26411e6038 R14: 00007f26411e5fa0 R15: 00007ffd415f2788 > </TASK> > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at [email protected]. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup
