binder: 20076:20080 ioctl 541b 20000000 returned -22
binder: 20076:20080 unknown command 8
binder: 20076:20080 ioctl c0306201 20012000 returned -22
binder: 20076:20080 BC_REQUEST_DEATH_NOTIFICATION invalid ref 0
======================================================
[ INFO: possible circular locking dependency detected ]
4.4.169+ #2 Not tainted
-------------------------------------------------------
syz-executor2/20085 is trying to acquire lock:
binder: 20076:20080 ioctl c0306201 20000040 returned -14
binder: 20076:20080 Acquire 1 refcount change on invalid ref 0 ret -22
binder: 20076:20091 ioctl 541b 20000000 returned -22
binder: 20076:20080 unknown command 8
binder: 20076:20080 ioctl c0306201 20012000 returned -22
binder: 20076:20080 unknown command 0
binder: 20076:20080 ioctl c0306201 20000040 returned -22
binder: 20076:20091 Acquire 1 refcount change on invalid ref 0 ret -22
 (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814af223>] pipe_lock_nested fs/pipe.c:65 [inline]
 (&pipe->mutex/1){+.+.+.}, at: [<ffffffff814af223>] pipe_lock+0x63/0x80 fs/pipe.c:73

but task is already holding lock:
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] file_start_write include/linux/fs.h:2543 [inline]
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] do_splice fs/splice.c:1403 [inline]
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] SYSC_splice fs/splice.c:1707 [inline]
 (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] SyS_splice+0xf2d/0x13a0 fs/splice.c:1690

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

       [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff8149e39f>] percpu_down_read include/linux/percpu-rwsem.h:26 [inline]
       [<ffffffff8149e39f>] __sb_start_write+0x1af/0x310 fs/super.c:1221
       [<ffffffff816c27d4>] sb_start_write include/linux/fs.h:1517 [inline]
       [<ffffffff816c27d4>] ext4_run_li_request fs/ext4/super.c:2674 [inline]
       [<ffffffff816c27d4>] ext4_lazyinit_thread fs/ext4/super.c:2773 [inline]
       [<ffffffff816c27d4>] ext4_lazyinit_thread+0x1e4/0x7b0 fs/ext4/super.c:2749
       [<ffffffff811340d3>] kthread+0x273/0x310 kernel/kthread.c:211
       [<ffffffff827157c5>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:537

       [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82708c01>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff82708c01>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
       [<ffffffff816cc7dd>] ext4_register_li_request+0x2fd/0x7d0 fs/ext4/super.c:2961
       [<ffffffff816ce016>] ext4_remount+0x1366/0x1b90 fs/ext4/super.c:4911
       [<ffffffff814a163b>] do_remount_sb2+0x41b/0x7a0 fs/super.c:771
       [<ffffffff8150221b>] do_remount fs/namespace.c:2347 [inline]
       [<ffffffff8150221b>] do_mount+0xfdb/0x2a40 fs/namespace.c:2860
       [<ffffffff81504670>] SYSC_mount fs/namespace.c:3063 [inline]
       [<ffffffff81504670>] SyS_mount+0x130/0x1d0 fs/namespace.c:3041
       [<ffffffff827153a1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82708c01>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff82708c01>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
       [<ffffffff816cc569>] ext4_register_li_request+0x89/0x7d0 fs/ext4/super.c:2934
       [<ffffffff816ce016>] ext4_remount+0x1366/0x1b90 fs/ext4/super.c:4911
       [<ffffffff814a163b>] do_remount_sb2+0x41b/0x7a0 fs/super.c:771
       [<ffffffff8150221b>] do_remount fs/namespace.c:2347 [inline]
       [<ffffffff8150221b>] do_mount+0xfdb/0x2a40 fs/namespace.c:2860
       [<ffffffff81504670>] SYSC_mount fs/namespace.c:3063 [inline]
       [<ffffffff81504670>] SyS_mount+0x130/0x1d0 fs/namespace.c:3041
       [<ffffffff827153a1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82710412>] down_read+0x42/0x60 kernel/locking/rwsem.c:22
       [<ffffffff814a0d81>] iterate_supers+0xe1/0x250 fs/super.c:537
       [<ffffffff819b0297>] selinux_complete_init+0x2f/0x31 security/selinux/hooks.c:6154
       [<ffffffff819a1ddd>] security_load_policy+0x69d/0x9c0 security/selinux/ss/services.c:2060
       [<ffffffff81978705>] sel_write_load+0x175/0xf90 security/selinux/selinuxfs.c:535
       [<ffffffff814962e6>] __vfs_write+0x116/0x3d0 fs/read_write.c:489
       [<ffffffff81497fe2>] vfs_write+0x182/0x4e0 fs/read_write.c:538
       [<ffffffff8149a61c>] SYSC_write fs/read_write.c:585 [inline]
       [<ffffffff8149a61c>] SyS_write+0xdc/0x1c0 fs/read_write.c:577
       [<ffffffff827153a1>] entry_SYSCALL_64_fastpath+0x1e/0x9a

       [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82708c01>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff82708c01>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
       [<ffffffff819762e9>] sel_commit_bools_write+0x89/0x260 security/selinux/selinuxfs.c:1142
       [<ffffffff814962e6>] __vfs_write+0x116/0x3d0 fs/read_write.c:489
       [<ffffffff814966b2>] __kernel_write+0x112/0x370 fs/read_write.c:511
       [<ffffffff815327dd>] write_pipe_buf+0x15d/0x1f0 fs/splice.c:1074
       [<ffffffff815334de>] splice_from_pipe_feed fs/splice.c:776 [inline]
       [<ffffffff815334de>] __splice_from_pipe+0x37e/0x7a0 fs/splice.c:901
       [<ffffffff81536558>] splice_from_pipe+0x108/0x170 fs/splice.c:936
       [<ffffffff8153664c>] default_file_splice_write+0x3c/0x80 fs/splice.c:1086
       [<ffffffff815376a1>] do_splice_from fs/splice.c:1128 [inline]
       [<ffffffff815376a1>] do_splice fs/splice.c:1404 [inline]
       [<ffffffff815376a1>] SYSC_splice fs/splice.c:1707 [inline]
       [<ffffffff815376a1>] SyS_splice+0xd71/0x13a0 fs/splice.c:1690
       [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
       [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
       [<ffffffff82716b50>] sysenter_flags_fixed+0xd/0x1a

       [<ffffffff81202b96>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
       [<ffffffff81202b96>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
       [<ffffffff81202b96>] validate_chain kernel/locking/lockdep.c:2144 [inline]
       [<ffffffff81202b96>] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213
       [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
       [<ffffffff82708c01>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
       [<ffffffff82708c01>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
       [<ffffffff814af223>] pipe_lock_nested fs/pipe.c:65 [inline]
       [<ffffffff814af223>] pipe_lock+0x63/0x80 fs/pipe.c:73
       [<ffffffff81533c59>] iter_file_splice_write+0x179/0xb30 fs/splice.c:974
       [<ffffffff815376a1>] do_splice_from fs/splice.c:1128 [inline]
       [<ffffffff815376a1>] do_splice fs/splice.c:1404 [inline]
       [<ffffffff815376a1>] SYSC_splice fs/splice.c:1707 [inline]
       [<ffffffff815376a1>] SyS_splice+0xd71/0x13a0 fs/splice.c:1690
       [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
       [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
       [<ffffffff82716b50>] sysenter_flags_fixed+0xd/0x1a

other info that might help us debug this:

Chain exists of:
 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#4);
                               lock(&eli->li_list_mtx);
                               lock(sb_writers#4);
  lock(&pipe->mutex/1);

 *** DEADLOCK ***

1 lock held by syz-executor2/20085:
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] file_start_write include/linux/fs.h:2543 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] do_splice fs/splice.c:1403 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] SYSC_splice fs/splice.c:1707 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8153785d>] SyS_splice+0xf2d/0x13a0 fs/splice.c:1690

stack backtrace:
CPU: 0 PID: 20085 Comm: syz-executor2 Not tainted 4.4.169+ #2
 0000000000000000 89cff4ee64b5428e ffff880095d97840 ffffffff81aab9c1
 ffffffff84055ac0 ffff8800b7e94740 ffffffff83abb610 ffffffff83aba380
 ffffffff83ac6080 ffff880095d97890 ffffffff813abaf4 ffffffff83e1d480
Call Trace:
 [<ffffffff81aab9c1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aab9c1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff813abaf4>] print_circular_bug.cold+0x2f7/0x44e kernel/locking/lockdep.c:1226
 [<ffffffff81202b96>] check_prev_add kernel/locking/lockdep.c:1853 [inline]
 [<ffffffff81202b96>] check_prevs_add kernel/locking/lockdep.c:1958 [inline]
 [<ffffffff81202b96>] validate_chain kernel/locking/lockdep.c:2144 [inline]
 [<ffffffff81202b96>] __lock_acquire+0x37d6/0x4f50 kernel/locking/lockdep.c:3213
 [<ffffffff81205d7e>] lock_acquire+0x15e/0x450 kernel/locking/lockdep.c:3592
 [<ffffffff82708c01>] __mutex_lock_common kernel/locking/mutex.c:521 [inline]
 [<ffffffff82708c01>] mutex_lock_nested+0xc1/0xb80 kernel/locking/mutex.c:621
 [<ffffffff814af223>] pipe_lock_nested fs/pipe.c:65 [inline]
 [<ffffffff814af223>] pipe_lock+0x63/0x80 fs/pipe.c:73
 [<ffffffff81533c59>] iter_file_splice_write+0x179/0xb30 fs/splice.c:974
 [<ffffffff815376a1>] do_splice_from fs/splice.c:1128 [inline]
 [<ffffffff815376a1>] do_splice fs/splice.c:1404 [inline]
 [<ffffffff815376a1>] SYSC_splice fs/splice.c:1707 [inline]
 [<ffffffff815376a1>] SyS_splice+0xd71/0x13a0 fs/splice.c:1690
 [<ffffffff8100603d>] do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
 [<ffffffff8100603d>] do_fast_syscall_32+0x32d/0xa90 arch/x86/entry/common.c:397
 [<ffffffff82716b50>] sysenter_flags_fixed+0xd/0x1a
blk_update_request: 250 callbacks suppressed
blk_update_request: I/O error, dev loop5, sector 0
buffer_io_error: 250 callbacks suppressed
Buffer I/O error on dev loop5, logical block 0, lost async page write
blk_update_request: I/O error, dev loop5, sector 8
Buffer I/O error on dev loop5, logical block 1, lost async page write
blk_update_request: I/O error, dev loop5, sector 16
Buffer I/O error on dev loop5, logical block 2, lost async page write
blk_update_request: I/O error, dev loop5, sector 24
Buffer I/O error on dev loop5, logical block 3, lost async page write
blk_update_request: I/O error, dev loop5, sector 32
Buffer I/O error on dev loop5, logical block 4, lost async page write
blk_update_request: I/O error, dev loop5, sector 40
Buffer I/O error on dev loop5, logical block 5, lost async page write
blk_update_request: I/O error, dev loop5, sector 48
Buffer I/O error on dev loop5, logical block 6, lost async page write
blk_update_request: I/O error, dev loop5, sector 56
Buffer I/O error on dev loop5, logical block 7, lost async page write
blk_update_request: I/O error, dev loop5, sector 64
Buffer I/O error on dev loop5, logical block 8, lost async page write
blk_update_request: I/O error, dev loop5, sector 72
Buffer I/O error on dev loop5, logical block 9, lost async page write
audit_printk_skb: 48 callbacks suppressed
audit: type=1400 audit(1546741747.563:1119): avc:  denied  { create } for  pid=20273 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741748.363:1120): avc:  denied  { create } for  pid=20320 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741749.013:1121): avc:  denied  { create } for  pid=20349 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741749.113:1122): avc:  denied  { create } for  pid=20377 comm="syz-executor1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741749.733:1123): avc:  denied  { create } for  pid=20392 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741749.773:1124): avc:  denied  { create } for  pid=20391 comm="syz-executor1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
blk_update_request: 510 callbacks suppressed
blk_update_request: I/O error, dev loop5, sector 0
buffer_io_error: 510 callbacks suppressed
Buffer I/O error on dev loop5, logical block 0, lost async page write
blk_update_request: I/O error, dev loop5, sector 8
Buffer I/O error on dev loop5, logical block 1, lost async page write
blk_update_request: I/O error, dev loop5, sector 16
Buffer I/O error on dev loop5, logical block 2, lost async page write
blk_update_request: I/O error, dev loop5, sector 24
Buffer I/O error on dev loop5, logical block 3, lost async page write
blk_update_request: I/O error, dev loop5, sector 32
Buffer I/O error on dev loop5, logical block 4, lost async page write
blk_update_request: I/O error, dev loop5, sector 40
Buffer I/O error on dev loop5, logical block 5, lost async page write
blk_update_request: I/O error, dev loop5, sector 48
Buffer I/O error on dev loop5, logical block 6, lost async page write
blk_update_request: I/O error, dev loop5, sector 56
Buffer I/O error on dev loop5, logical block 7, lost async page write
blk_update_request: I/O error, dev loop5, sector 64
Buffer I/O error on dev loop5, logical block 8, lost async page write
blk_update_request: I/O error, dev loop5, sector 72
Buffer I/O error on dev loop5, logical block 9, lost async page write
audit: type=1400 audit(1546741750.103:1125): avc:  denied  { create } for  pid=20442 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741750.413:1126): avc:  denied  { create } for  pid=20464 comm="syz-executor1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741750.773:1127): avc:  denied  { create } for  pid=20507 comm="syz-executor3" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0
audit: type=1400 audit(1546741750.803:1128): avc:  denied  { create } for  pid=20508 comm="syz-executor1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=0