Messages in this thread | | | Date | Thu, 24 Nov 2022 01:13:41 -0800 | Subject | [syzbot] possible deadlock in btrfs_search_forward | From | syzbot <> |
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Hello,
syzbot found the following issue on:
HEAD commit: 4312098baf37 Merge tag 'spi-fix-v6.1-rc6' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17166e3d880000 kernel config: https://syzkaller.appspot.com/x/.config?x=8d01b6e3197974dd dashboard link: https://syzkaller.appspot.com/bug?extid=3cf137e672e75b602171 compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/4b7073d20a37/disk-4312098b.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/36a0367a5593/vmlinux-4312098b.xz kernel image: https://storage.googleapis.com/syzbot-assets/265bedb3086b/bzImage-4312098b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3cf137e672e75b602171@syzkaller.appspotmail.com
BTRFS info (device loop2): enabling ssd optimizations ====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00012-g4312098baf37 #0 Not tainted ------------------------------------------------------ syz-executor.2/11489 is trying to acquire lock: ffff88801927df98 (&mm->mmap_lock#2){++++}-{3:3}, at: __might_fault+0x8f/0x110 mm/memory.c:5645
but task is already holding lock: ffff888024223838 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] ffff888024223838 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] ffff888024223838 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (btrfs-root-00){++++}-{3:3}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 down_read_nested+0x3c/0x50 kernel/locking/rwsem.c:1634 __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279 btrfs_search_forward+0x10f/0xe70 fs/btrfs/ctree.c:4488 btrfs_uuid_scan_kthread+0x25e/0xbc0 fs/btrfs/volumes.c:4654 kthread+0x266/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 join_transaction+0x19f/0xe60 fs/btrfs/transaction.c:299 start_transaction+0x6fb/0x1180 fs/btrfs/transaction.c:658 btrfs_create_common+0x2c6/0x420 fs/btrfs/inode.c:6633 lookup_open fs/namei.c:3413 [inline] open_last_lookups fs/namei.c:3481 [inline] path_openat+0x12d0/0x2df0 fs/namei.c:3710 do_filp_open+0x264/0x4f0 fs/namei.c:3740 do_sys_openat2+0x124/0x4e0 fs/open.c:1310 do_sys_open fs/open.c:1326 [inline] __do_sys_open fs/open.c:1334 [inline] __se_sys_open fs/open.c:1330 [inline] __x64_sys_open+0x221/0x270 fs/open.c:1330 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #1 (btrfs_trans_num_writers){++++}-{0:0}: reacquire_held_locks+0x386/0x650 kernel/locking/lockdep.c:5193 __lock_release kernel/locking/lockdep.c:5382 [inline] lock_release+0x2e2/0x820 kernel/locking/lockdep.c:5688 percpu_up_read include/linux/percpu-rwsem.h:99 [inline] __sb_end_write include/linux/fs.h:1821 [inline] sb_end_intwrite+0x1e/0x1a0 include/linux/fs.h:1877 __btrfs_end_transaction+0x388/0x790 fs/btrfs/transaction.c:995 btrfs_dirty_inode+0x177/0x1c0 fs/btrfs/inode.c:6099 inode_update_time fs/inode.c:1871 [inline] touch_atime+0x315/0x630 fs/inode.c:1944 file_accessed include/linux/fs.h:2521 [inline] btrfs_file_mmap+0xbb/0x120 fs/btrfs/file.c:2333 call_mmap include/linux/fs.h:2196 [inline] mmap_region+0xfe6/0x1e20 mm/mmap.c:2625 do_mmap+0x8d9/0xf30 mm/mmap.c:1412 vm_mmap_pgoff+0x19e/0x2b0 mm/util.c:520 ksys_mmap_pgoff+0x48c/0x6d0 mm/mmap.c:1458 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
-> #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+0x1898/0x6ae0 kernel/locking/lockdep.c:3831 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055 lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 __might_fault+0xb2/0x110 mm/memory.c:5646 _copy_to_user+0x26/0x130 lib/usercopy.c:29 copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x8cf/0xa90 fs/btrfs/ioctl.c:3203 btrfs_ioctl+0xb7c/0xc10 fs/btrfs/ioctl.c:5556 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
other info that might help us debug this:
Chain exists of: &mm->mmap_lock#2 --> btrfs_trans_num_extwriters --> btrfs-root-00
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(btrfs-root-00); lock(btrfs_trans_num_extwriters); lock(btrfs-root-00); lock(&mm->mmap_lock#2);
*** DEADLOCK ***
1 lock held by syz-executor.2/11489: #0: ffff888024223838 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock fs/btrfs/locking.c:134 [inline] #0: ffff888024223838 (btrfs-root-00){++++}-{3:3}, at: btrfs_tree_read_lock fs/btrfs/locking.c:140 [inline] #0: ffff888024223838 (btrfs-root-00){++++}-{3:3}, at: btrfs_read_lock_root_node+0x2b4/0x400 fs/btrfs/locking.c:279
stack backtrace: CPU: 0 PID: 11489 Comm: syz-executor.2 Not tainted 6.1.0-rc6-syzkaller-00012-g4312098baf37 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 check_noncircular+0x2cc/0x390 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+0x1898/0x6ae0 kernel/locking/lockdep.c:3831 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055 lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 __might_fault+0xb2/0x110 mm/memory.c:5646 _copy_to_user+0x26/0x130 lib/usercopy.c:29 copy_to_user include/linux/uaccess.h:169 [inline] btrfs_ioctl_get_subvol_rootref+0x8cf/0xa90 fs/btrfs/ioctl.c:3203 btrfs_ioctl+0xb7c/0xc10 fs/btrfs/ioctl.c:5556 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f1731e8c0d9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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:00007f1732ba2168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f1731fabf80 RCX: 00007f1731e8c0d9 RDX: 0000000020049dc0 RSI: 00000000d000943d RDI: 0000000000000004 RBP: 00007f1731ee7ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd2e5e53af R14: 00007f1732ba2300 R15: 0000000000022000 </TASK>
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