====================================================== WARNING: possible circular locking dependency detected 5.4.0-rc3-next-20191017 #0 Not tainted ------------------------------------------------------ syz-executor945/8855 is trying to acquire lock: ffff8880a5912e98 (&mm->mmap_sem#2){++++}, at: __might_fault+0xfb/0x1e0 mm/memory.c:4471 but task is already holding lock: ffff8880a772a500 (&rp->fetch_lock){+.+.}, at: mon_bin_read+0x60/0x640 drivers/usb/mon/mon_bin.c:813 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&rp->fetch_lock){+.+.}: __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 mon_bin_vma_fault+0x73/0x2d0 drivers/usb/mon/mon_bin.c:1237 __do_fault+0x111/0x540 mm/memory.c:3114 do_read_fault mm/memory.c:3511 [inline] do_fault mm/memory.c:3640 [inline] handle_pte_fault mm/memory.c:3871 [inline] __handle_mm_fault+0x2d49/0x3fd0 mm/memory.c:3995 handle_mm_fault+0x3b2/0xa90 mm/memory.c:4032 faultin_page mm/gup.c:640 [inline] __get_user_pages+0x7cf/0x1b20 mm/gup.c:845 populate_vma_page_range+0x20d/0x2a0 mm/gup.c:1223 __mm_populate+0x204/0x380 mm/gup.c:1271 mm_populate include/linux/mm.h:2370 [inline] vm_mmap_pgoff+0x213/0x230 mm/util.c:511 ksys_mmap_pgoff+0x4aa/0x630 mm/mmap.c:1604 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline] __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&mm->mmap_sem#2){++++}: check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487 __might_fault mm/memory.c:4472 [inline] __might_fault+0x15e/0x1e0 mm/memory.c:4457 _copy_to_user+0x30/0x160 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:152 [inline] mon_bin_read+0x329/0x640 drivers/usb/mon/mon_bin.c:825 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rp->fetch_lock); lock(&mm->mmap_sem#2); lock(&rp->fetch_lock); lock(&mm->mmap_sem#2); *** DEADLOCK *** 1 lock held by syz-executor945/8855: #0: ffff8880a772a500 (&rp->fetch_lock){+.+.}, at: mon_bin_read+0x60/0x640 drivers/usb/mon/mon_bin.c:813 stack backtrace: CPU: 0 PID: 8855 Comm: syz-executor945 Not tainted 5.4.0-rc3-next-20191017 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809 check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487 __might_fault mm/memory.c:4472 [inline] __might_fault+0x15e/0x1e0 mm/memory.c:4457 _copy_to_user+0x30/0x160 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:152 [inline] mon_bin_read+0x329/0x640 drivers/usb/mon/mon_bin.c:825 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x44a779 Code: e8 ec b6 02 00 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 cb cc fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f51a031cce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 000000000044a779 RDX: 0000000000000016 RSI: 0000000020000100 RDI: 0000000000000003 RBP: 00000000006dbc30 R08: 00007f51a031d700 R09: 0000000000000000 R10: 00007f51a031d700 R11: 0000000000000246 R12: 00000000006dbc3c R13: 00007ffdeca4e58f R14: 00007f51a031d9c0 R15: 0000000000000001