On 11/04/22 09:00, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: f2f32f8af2b0 Merge tag 'for-6.1-rc3-tag' of git://git.kern.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=137d52ca880000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d080a4bd239918dd > dashboard link: https://syzkaller.appspot.com/bug?extid=ca56f14c500045350f93 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/b4f72e7a4c11/disk-f2f32f8a.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/3f88997ad7c9/vmlinux-f2f32f8a.xz > kernel image: https://storage.googleapis.com/syzbot-assets/b4b5b3963e2d/bzImage-f2f32f8a.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+ca56f14c500045350f93@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 6.1.0-rc3-syzkaller-00152-gf2f32f8af2b0 #0 Not tainted > ------------------------------------------------------ > syz-executor.2/5665 is trying to acquire lock: > ffff88801c74c298 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0xa1/0x170 mm/memory.c:5645 > > but task is already holding lock: > ffff88801c4f3078 (&vma_lock->rw_sema){++++}-{3:3}, at: hugetlb_vma_lock_read mm/hugetlb.c:6816 [inline] > ffff88801c4f3078 (&vma_lock->rw_sema){++++}-{3:3}, at: hugetlb_fault+0x40a/0x2060 mm/hugetlb.c:5859 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&vma_lock->rw_sema){++++}-{3:3}: > down_write+0x90/0x220 kernel/locking/rwsem.c:1562 > hugetlb_vma_lock_write mm/hugetlb.c:6834 [inline] > __unmap_hugepage_range_final+0x97/0x340 mm/hugetlb.c:5202 > unmap_single_vma+0x23d/0x2a0 mm/memory.c:1690 > unmap_vmas+0x21e/0x370 mm/memory.c:1733 > exit_mmap+0x189/0x7a0 mm/mmap.c:3090 > __mmput+0x128/0x4c0 kernel/fork.c:1185 > mmput+0x5c/0x70 kernel/fork.c:1207 > exit_mm kernel/exit.c:516 [inline] > do_exit+0xa39/0x2a20 kernel/exit.c:807 > do_group_exit+0xd0/0x2a0 kernel/exit.c:950 > get_signal+0x21a1/0x2430 kernel/signal.c:2858 > arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869 > exit_to_user_mode_loop kernel/entry/common.c:168 [inline] > exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 > __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] > syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:296 > __do_fast_syscall_32+0x72/0xf0 arch/x86/entry/common.c:181 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x70/0x82 > > -> #0 (&mm->mmap_lock#2){++++}-{3:3}: > check_prev_add kernel/locking/lockdep.c:3097 [inline] > check_prevs_add kernel/locking/lockdep.c:3216 [inline] > validate_chain kernel/locking/lockdep.c:3831 [inline] > __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 > lock_acquire kernel/locking/lockdep.c:5668 [inline] > lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 > __might_fault mm/memory.c:5646 [inline] > __might_fault+0x104/0x170 mm/memory.c:5639 > _copy_from_user+0x25/0x170 lib/usercopy.c:13 > copy_from_user include/linux/uaccess.h:161 [inline] > snd_rawmidi_kernel_write1+0x366/0x880 sound/core/rawmidi.c:1549 > snd_rawmidi_write+0x273/0xbb0 sound/core/rawmidi.c:1618 > vfs_write+0x2d7/0xdd0 fs/read_write.c:582 > ksys_write+0x1e8/0x250 fs/read_write.c:637 > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x70/0x82 > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&vma_lock->rw_sema); > lock(&mm->mmap_lock#2); > lock(&vma_lock->rw_sema); > lock(&mm->mmap_lock#2); I may not be reading the report correctly, but I can not see how we acquire the hugetlb vma_lock before trying to acquire mmap_lock in stack 0. We would not acquire the vma_lock until we enter hugetlb fault processing (not in the stack). Adding Miaohe Lin on Cc due to previous help with vma_lock potential deadlock situations. Miaohe, does this make sense to you? -- Mike Kravetz > > > 1 lock held by syz-executor.2/5665: > #0: ffff88801c4f3078 (&vma_lock->rw_sema){++++}-{3:3}, at: hugetlb_vma_lock_read mm/hugetlb.c:6816 [inline] > #0: ffff88801c4f3078 (&vma_lock->rw_sema){++++}-{3:3}, at: hugetlb_fault+0x40a/0x2060 mm/hugetlb.c:5859 > > stack backtrace: > CPU: 1 PID: 5665 Comm: syz-executor.2 Not tainted 6.1.0-rc3-syzkaller-00152-gf2f32f8af2b0 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177 > check_prev_add kernel/locking/lockdep.c:3097 [inline] > check_prevs_add kernel/locking/lockdep.c:3216 [inline] > validate_chain kernel/locking/lockdep.c:3831 [inline] > __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 > lock_acquire kernel/locking/lockdep.c:5668 [inline] > lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 > __might_fault mm/memory.c:5646 [inline] > __might_fault+0x104/0x170 mm/memory.c:5639 > _copy_from_user+0x25/0x170 lib/usercopy.c:13 > copy_from_user include/linux/uaccess.h:161 [inline] > snd_rawmidi_kernel_write1+0x366/0x880 sound/core/rawmidi.c:1549 > snd_rawmidi_write+0x273/0xbb0 sound/core/rawmidi.c:1618 > vfs_write+0x2d7/0xdd0 fs/read_write.c:582 > ksys_write+0x1e8/0x250 fs/read_write.c:637 > do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline] > __do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 > do_fast_syscall_32+0x2f/0x70 arch/x86/entry/common.c:203 > entry_SYSENTER_compat_after_hwframe+0x70/0x82 > RIP: 0023:0xf7fad549 > Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > RSP: 002b:00000000f7f875cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004 > RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000000 > RDX: 00000000c86ade39 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > ---------------- > Code disassembly (best guess): > 0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi > 4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d > a: 10 06 adc %al,(%rsi) > c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > 10: 10 07 adc %al,(%rdi) > 12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > 16: 10 08 adc %cl,(%rax) > 18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > 1c: 00 00 add %al,(%rax) > 1e: 00 00 add %al,(%rax) > 20: 00 51 52 add %dl,0x52(%rcx) > 23: 55 push %rbp > 24: 89 e5 mov %esp,%ebp > 26: 0f 34 sysenter > 28: cd 80 int $0x80 > * 2a: 5d pop %rbp <-- trapping instruction > 2b: 5a pop %rdx > 2c: 59 pop %rcx > 2d: c3 retq > 2e: 90 nop > 2f: 90 nop > 30: 90 nop > 31: 90 nop > 32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > 39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > --- > 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.
