I think this has the same underlying cause as the other kernfs-overlayfs deadlocks. #syz dup: possible deadlock in kernfs_fop_llseek On Sun, 7 Apr 2024 at 18:43, syzbot <syzbot+fa60c773a1654e2eda40@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 3e92c1e6cd87 Merge tag 'selinux-pr-20240402' of git://git... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16ebae03180000 > kernel config: https://syzkaller.appspot.com/x/.config?x=411644804960f423 > dashboard link: https://syzkaller.appspot.com/bug?extid=fa60c773a1654e2eda40 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-3e92c1e6.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/34cc55fbbf72/vmlinux-3e92c1e6.xz > kernel image: https://storage.googleapis.com/syzbot-assets/09668ee3251b/bzImage-3e92c1e6.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+fa60c773a1654e2eda40@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 6.9.0-rc2-syzkaller-00042-g3e92c1e6cd87 #0 Not tainted > ------------------------------------------------------ > syz-executor.2/22789 is trying to acquire lock: > ffff888032f275b0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:803 [inline] > ffff888032f275b0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: lookup_slow fs/namei.c:1708 [inline] > ffff888032f275b0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}, at: walk_component+0x342/0x5b0 fs/namei.c:2004 > > but task is already holding lock: > ffff888040373488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x281/0x500 fs/kernfs/file.c:325 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #3 (&of->mutex){+.+.}-{3:3}: > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 > kernfs_fop_write_iter+0x281/0x500 fs/kernfs/file.c:325 > call_write_iter include/linux/fs.h:2108 [inline] > iter_file_splice_write+0x906/0x10b0 fs/splice.c:743 > do_splice_from fs/splice.c:941 [inline] > do_splice+0x12c7/0x1f10 fs/splice.c:1354 > __do_splice+0x327/0x360 fs/splice.c:1436 > __do_sys_splice fs/splice.c:1652 [inline] > __se_sys_splice fs/splice.c:1634 [inline] > __x64_sys_splice+0x1d2/0x260 fs/splice.c:1634 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x72/0x7a > > -> #2 (&pipe->mutex){+.+.}-{3:3}: > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 > pipe_lock fs/pipe.c:92 [inline] > pipe_lock+0x64/0x80 fs/pipe.c:89 > iter_file_splice_write+0x1f0/0x10b0 fs/splice.c:687 > do_splice_from fs/splice.c:941 [inline] > do_splice+0x12c7/0x1f10 fs/splice.c:1354 > __do_splice+0x327/0x360 fs/splice.c:1436 > __do_sys_splice fs/splice.c:1652 [inline] > __se_sys_splice fs/splice.c:1634 [inline] > __x64_sys_splice+0x1d2/0x260 fs/splice.c:1634 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x72/0x7a > > -> #1 (sb_writers#5){.+.+}-{0:0}: > percpu_down_read include/linux/percpu-rwsem.h:51 [inline] > __sb_start_write include/linux/fs.h:1662 [inline] > sb_start_write include/linux/fs.h:1798 [inline] > mnt_want_write+0x6f/0x450 fs/namespace.c:409 > ovl_xattr_set+0x136/0x530 fs/overlayfs/xattrs.c:63 > ovl_own_xattr_set+0x86/0xd0 fs/overlayfs/xattrs.c:213 > __vfs_setxattr+0x173/0x1e0 fs/xattr.c:200 > __vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:234 > __vfs_setxattr_locked+0x182/0x260 fs/xattr.c:295 > vfs_setxattr+0x146/0x350 fs/xattr.c:321 > do_setxattr+0x146/0x170 fs/xattr.c:629 > setxattr+0x15d/0x180 fs/xattr.c:652 > path_setxattr+0x179/0x1e0 fs/xattr.c:671 > __do_sys_setxattr fs/xattr.c:687 [inline] > __se_sys_setxattr fs/xattr.c:683 [inline] > __x64_sys_setxattr+0xc4/0x160 fs/xattr.c:683 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x72/0x7a > > -> #0 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}: > check_prev_add kernel/locking/lockdep.c:3134 [inline] > check_prevs_add kernel/locking/lockdep.c:3253 [inline] > validate_chain kernel/locking/lockdep.c:3869 [inline] > __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 > lock_acquire kernel/locking/lockdep.c:5754 [inline] > lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 > down_read+0x9a/0x330 kernel/locking/rwsem.c:1526 > inode_lock_shared include/linux/fs.h:803 [inline] > lookup_slow fs/namei.c:1708 [inline] > walk_component+0x342/0x5b0 fs/namei.c:2004 > lookup_last fs/namei.c:2461 [inline] > path_lookupat+0x17f/0x770 fs/namei.c:2485 > filename_lookup+0x1e5/0x5b0 fs/namei.c:2514 > kern_path+0x35/0x50 fs/namei.c:2622 > lookup_bdev+0xd9/0x280 block/bdev.c:1079 > resume_store+0x1d8/0x460 kernel/power/hibernate.c:1235 > kobj_attr_store+0x55/0x80 lib/kobject.c:840 > sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:136 > kernfs_fop_write_iter+0x343/0x500 fs/kernfs/file.c:334 > call_write_iter include/linux/fs.h:2108 [inline] > new_sync_write fs/read_write.c:497 [inline] > vfs_write+0x6db/0x1100 fs/read_write.c:590 > ksys_write+0x12f/0x260 fs/read_write.c:643 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x72/0x7a > > other info that might help us debug this: > > Chain exists of: > &ovl_i_mutex_dir_key[depth] --> &pipe->mutex --> &of->mutex > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&of->mutex); > lock(&pipe->mutex); > lock(&of->mutex); > rlock(&ovl_i_mutex_dir_key[depth]); > > *** DEADLOCK *** > > 4 locks held by syz-executor.2/22789: > #0: ffff88802cc70ac8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xeb/0x180 fs/file.c:1191 > #1: ffff88802533e420 (sb_writers#9){.+.+}-{0:0}, at: ksys_write+0x12f/0x260 fs/read_write.c:643 > #2: ffff888040373488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x281/0x500 fs/kernfs/file.c:325 > #3: ffff8880196eb5a8 (kn->active#85){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x2a4/0x500 fs/kernfs/file.c:326 > > stack backtrace: > CPU: 0 PID: 22789 Comm: syz-executor.2 Not tainted 6.9.0-rc2-syzkaller-00042-g3e92c1e6cd87 #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 > check_noncircular+0x31a/0x400 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 kernel/locking/lockdep.c:3869 [inline] > __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 > lock_acquire kernel/locking/lockdep.c:5754 [inline] > lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 > down_read+0x9a/0x330 kernel/locking/rwsem.c:1526 > inode_lock_shared include/linux/fs.h:803 [inline] > lookup_slow fs/namei.c:1708 [inline] > walk_component+0x342/0x5b0 fs/namei.c:2004 > lookup_last fs/namei.c:2461 [inline] > path_lookupat+0x17f/0x770 fs/namei.c:2485 > filename_lookup+0x1e5/0x5b0 fs/namei.c:2514 > kern_path+0x35/0x50 fs/namei.c:2622 > lookup_bdev+0xd9/0x280 block/bdev.c:1079 > resume_store+0x1d8/0x460 kernel/power/hibernate.c:1235 > kobj_attr_store+0x55/0x80 lib/kobject.c:840 > sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:136 > kernfs_fop_write_iter+0x343/0x500 fs/kernfs/file.c:334 > call_write_iter include/linux/fs.h:2108 [inline] > new_sync_write fs/read_write.c:497 [inline] > vfs_write+0x6db/0x1100 fs/read_write.c:590 > ksys_write+0x12f/0x260 fs/read_write.c:643 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x72/0x7a > RIP: 0033:0x7fb6a4e7dde9 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fb6a5b2f0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 00007fb6a4fabf80 RCX: 00007fb6a4e7dde9 > RDX: 0000000000000012 RSI: 0000000020000000 RDI: 0000000000000007 > RBP: 00007fb6a4eca47a R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 000000000000004d R14: 00007fb6a4fabf80 R15: 00007ffdad03fdb8 > </TASK> > PM: Image not found (code -6) > > > --- > 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. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > 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 >
