Hello, syzbot found the following issue on: HEAD commit: ae00c445390b Add linux-next specific files for 20240212 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=17478592180000 kernel config: https://syzkaller.appspot.com/x/.config?x=4eb3a27eddb32a14 dashboard link: https://syzkaller.appspot.com/bug?extid=27f783f9d240834c9d44 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17406e42180000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111cb500180000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/8b2a2d0b511f/disk-ae00c445.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/a668a09c9d03/vmlinux-ae00c445.xz kernel image: https://storage.googleapis.com/syzbot-assets/4ad623928692/bzImage-ae00c445.xz The issue was bisected to: commit 31d97016c80a83daa4c938014c81282810a14773 Author: Lokesh Gidra <lokeshgidra@xxxxxxxxxx> Date: Thu Feb 8 21:22:04 2024 +0000 userfaultfd: use per-vma locks in userfaultfd operations bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=129ff100180000 final oops: https://syzkaller.appspot.com/x/report.txt?x=119ff100180000 console output: https://syzkaller.appspot.com/x/log.txt?x=169ff100180000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+27f783f9d240834c9d44@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 31d97016c80a ("userfaultfd: use per-vma locks in userfaultfd operations") ====================================================== WARNING: possible circular locking dependency detected 6.8.0-rc4-next-20240212-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor800/5064 is trying to acquire lock: ffff888021d401a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock include/linux/mmap_lock.h:146 [inline] ffff888021d401a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_vma+0xc5/0x260 mm/userfaultfd.c:73 but task is already holding lock: ffff88802b989730 (&vma->vm_lock->lock){++++}-{3:3}, at: lock_vma+0x1a1/0x260 mm/userfaultfd.c:87 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&vma->vm_lock->lock){++++}-{3:3}: lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 down_write+0x3a/0x50 kernel/locking/rwsem.c:1579 vma_start_write include/linux/mm.h:716 [inline] vma_link+0x2c6/0x550 mm/mmap.c:416 insert_vm_struct+0x1a3/0x260 mm/mmap.c:3331 __bprm_mm_init fs/exec.c:282 [inline] bprm_mm_init fs/exec.c:384 [inline] alloc_bprm+0x543/0xa00 fs/exec.c:1579 kernel_execve+0x99/0xa10 fs/exec.c:2008 try_to_run_init_process init/main.c:1361 [inline] kernel_init+0xe8/0x2b0 init/main.c:1488 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:242 -> #0 (&mm->mmap_lock){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526 mmap_read_lock include/linux/mmap_lock.h:146 [inline] lock_vma+0xc5/0x260 mm/userfaultfd.c:73 find_and_lock_vmas mm/userfaultfd.c:1405 [inline] move_pages+0x18c/0xff0 mm/userfaultfd.c:1546 userfaultfd_move fs/userfaultfd.c:2008 [inline] userfaultfd_ioctl+0x5c10/0x72c0 fs/userfaultfd.c:2126 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:857 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&vma->vm_lock->lock); lock(&mm->mmap_lock); lock(&vma->vm_lock->lock); rlock(&mm->mmap_lock); *** DEADLOCK *** 1 lock held by syz-executor800/5064: #0: ffff88802b989730 (&vma->vm_lock->lock){++++}-{3:3}, at: lock_vma+0x1a1/0x260 mm/userfaultfd.c:87 stack backtrace: CPU: 1 PID: 5064 Comm: syz-executor800 Not tainted 6.8.0-rc4-next-20240212-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187 check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754 down_read+0xb1/0xa40 kernel/locking/rwsem.c:1526 mmap_read_lock include/linux/mmap_lock.h:146 [inline] lock_vma+0xc5/0x260 mm/userfaultfd.c:73 find_and_lock_vmas mm/userfaultfd.c:1405 [inline] move_pages+0x18c/0xff0 mm/userfaultfd.c:1546 userfaultfd_move fs/userfaultfd.c:2008 [inline] userfaultfd_ioctl+0x5c10/0x72c0 fs/userfaultfd.c:2126 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:857 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 RIP: 0033:0x7f86fc35f329 Code: 48 83 c4 28 c3 e8 37 17 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd53428e38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffd53429008 RCX: 00007f86fc35f329 RDX: 0000000020000040 RSI: 00000000c028aa05 RDI: --- 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 syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. 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
