====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 Tainted: G U ------------------------------------------------------ syz.6.6032/32631 is trying to acquire lock: ffff8880335c5be0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:193 [inline] ffff8880335c5be0 (&mm->mmap_lock){++++}-{4:4}, at: get_mmap_lock_carefully mm/memory.c:6355 [inline] ffff8880335c5be0 (&mm->mmap_lock){++++}-{4:4}, at: lock_mm_and_find_vma+0x3e7/0x6e0 mm/memory.c:6406 but task is already holding lock: ffff88801c2f7948 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x160/0x930 fs/kernfs/dir.c:1890 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&root->kernfs_rwsem){++++}-{4:4}: down_read+0x9b/0x480 kernel/locking/rwsem.c:1524 kernfs_find_and_get_ns+0x2f/0x70 fs/kernfs/dir.c:933 kernfs_find_and_get include/linux/kernfs.h:612 [inline] sysfs_remove_group+0x73/0x180 fs/sysfs/group.c:311 topology_remove_dev+0x22/0x30 drivers/base/topology.c:199 cpuhp_invoke_callback+0x3d2/0xa10 kernel/cpu.c:194 __cpuhp_invoke_callback_range+0x101/0x210 kernel/cpu.c:967 cpuhp_invoke_callback_range kernel/cpu.c:991 [inline] cpuhp_down_callbacks kernel/cpu.c:1384 [inline] _cpu_down+0x422/0xf20 kernel/cpu.c:1445 __cpu_down_maps_locked+0x6c/0x90 kernel/cpu.c:1470 work_for_cpu_fn+0x52/0xa0 kernel/workqueue.c:6733 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 process_scheduled_works kernel/workqueue.c:3319 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #3 (cpu_hotplug_lock){++++}-{0:0}: percpu_down_read include/linux/percpu-rwsem.h:52 [inline] cpus_read_lock+0x42/0x160 kernel/cpu.c:490 ring_buffer_resize+0x7ea/0x1560 kernel/trace/ring_buffer.c:2894 __tracing_resize_ring_buffer.part.0+0x52/0x1f0 kernel/trace/trace.c:5943 __tracing_resize_ring_buffer kernel/trace/trace.c:5937 [inline] tracing_update_buffers+0x102/0x130 kernel/trace/trace.c:6170 ftrace_event_write+0x14a/0x290 kernel/trace/trace_events.c:1494 vfs_write+0x25c/0x1180 fs/read_write.c:682 ksys_write+0x12a/0x240 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&buffer->mutex#2){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 ring_buffer_map+0x144/0xa40 kernel/trace/ring_buffer.c:7157 tracing_buffers_mmap+0x120/0x1c0 kernel/trace/trace.c:8519 call_mmap include/linux/fs.h:2243 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2353 [inline] __mmap_new_vma mm/vma.c:2417 [inline] __mmap_region+0x1485/0x27c0 mm/vma.c:2519 mmap_region+0x1ab/0x3f0 mm/vma.c:2597 do_mmap+0xd8e/0x11b0 mm/mmap.c:561 vm_mmap_pgoff+0x281/0x450 mm/util.c:579 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:607 __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/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&cpu_buffer->mapping_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:746 ring_buffer_map+0xdc/0xa40 kernel/trace/ring_buffer.c:7146 tracing_buffers_mmap+0x120/0x1c0 kernel/trace/trace.c:8519 call_mmap include/linux/fs.h:2243 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2353 [inline] __mmap_new_vma mm/vma.c:2417 [inline] __mmap_region+0x1485/0x27c0 mm/vma.c:2519 mmap_region+0x1ab/0x3f0 mm/vma.c:2597 do_mmap+0xd8e/0x11b0 mm/mmap.c:561 vm_mmap_pgoff+0x281/0x450 mm/util.c:579 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:607 __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/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&mm->mmap_lock){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 down_read_killable+0x9e/0x4b0 kernel/locking/rwsem.c:1547 mmap_read_lock_killable include/linux/mmap_lock.h:193 [inline] get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x3e7/0x6e0 mm/memory.c:6406 do_user_addr_fault+0x2ac/0x1370 arch/x86/mm/fault.c:1360 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir+0x29c/0x5f0 fs/readdir.c:290 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x3d5/0x930 fs/kernfs/dir.c:1907 iterate_dir+0x293/0xb40 fs/readdir.c:108 __do_sys_getdents fs/readdir.c:322 [inline] __se_sys_getdents fs/readdir.c:308 [inline] __x64_sys_getdents+0x14d/0x2c0 fs/readdir.c:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 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: &mm->mmap_lock --> cpu_hotplug_lock --> &root->kernfs_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&root->kernfs_rwsem); lock(cpu_hotplug_lock); lock(&root->kernfs_rwsem); rlock(&mm->mmap_lock); *** DEADLOCK *** 3 locks held by syz.6.6032/32631: #0: ffff88802fd69eb8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2a2/0x370 fs/file.c:1213 #1: ffff888076475060 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x18b/0xb40 fs/readdir.c:101 #2: ffff88801c2f7948 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x160/0x930 fs/kernfs/dir.c:1890 stack backtrace: CPU: 1 UID: 0 PID: 32631 Comm: syz.6.6032 Tainted: G U 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 PREEMPT(full) Tainted: [U]=USER Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025 Call Trace: __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:2079 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1173/0x1ba0 kernel/locking/lockdep.c:5235 lock_acquire kernel/locking/lockdep.c:5866 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823 down_read_killable+0x9e/0x4b0 kernel/locking/rwsem.c:1547 mmap_read_lock_killable include/linux/mmap_lock.h:193 [inline] get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x3e7/0x6e0 mm/memory.c:6406 do_user_addr_fault+0x2ac/0x1370 arch/x86/mm/fault.c:1360 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:filldir+0x29c/0x5f0 fs/readdir.c:290 Code: db e8 58 31 84 ff 89 d8 48 83 c4 50 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc e8 3e 31 84 ff 0f 01 cb 0f ae e8 48 8b 04 24 <49> 89 47 08 e8 2b 31 84 ff 4c 8b 7c 24 30 48 8b 44 24 10 49 89 07 RSP: 0018:ffffc9000b167cd8 EFLAGS: 00050293 RAX: 000000004127eee8 RBX: ffffc9000b167e80 RCX: ffffffff82367b3a RDX: ffff88802e525a00 RSI: ffffffff82367b92 RDI: 0000000000000006 RBP: 0000000000000268 R08: 0000000000000006 R09: 0000000000000218 R10: 0000000000000268 R11: 0000000000000000 R12: 000000000000000e R13: 0000000000000028 R14: ffff888078a86d00 R15: 0000000000000218 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x3d5/0x930 fs/kernfs/dir.c:1907 iterate_dir+0x293/0xb40 fs/readdir.c:108 __do_sys_getdents fs/readdir.c:322 [inline] __se_sys_getdents fs/readdir.c:308 [inline] __x64_sys_getdents+0x14d/0x2c0 fs/readdir.c:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb1cb38e969 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:00007fb1c91f6038 EFLAGS: 00000246 ORIG_RAX: 000000000000004e RAX: ffffffffffffffda RBX: 00007fb1cb5b6160 RCX: 00007fb1cb38e969 RDX: 0000000000400018 RSI: 0000000000000000 RDI: 000000000000006b RBP: 00007fb1cb410ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fb1cb5b6160 R15: 00007fff6d727d08 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: e8 58 31 84 ff call 0xff84315d 5: 89 d8 mov %ebx,%eax 7: 48 83 c4 50 add $0x50,%rsp b: 5b pop %rbx c: 5d pop %rbp d: 41 5c pop %r12 f: 41 5d pop %r13 11: 41 5e pop %r14 13: 41 5f pop %r15 15: c3 ret 16: cc int3 17: cc int3 18: cc int3 19: cc int3 1a: e8 3e 31 84 ff call 0xff84315d 1f: 0f 01 cb stac 22: 0f ae e8 lfence 25: 48 8b 04 24 mov (%rsp),%rax * 29: 49 89 47 08 mov %rax,0x8(%r15) <-- trapping instruction 2d: e8 2b 31 84 ff call 0xff84315d 32: 4c 8b 7c 24 30 mov 0x30(%rsp),%r15 37: 48 8b 44 24 10 mov 0x10(%rsp),%rax 3c: 49 89 07 mov %rax,(%r15)