====================================================== WARNING: possible circular locking dependency detected 5.14.0-rc2-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/10138 is trying to acquire lock: ffff88802473c868 (&pipe->mutex/1){+.+.}-{3:3}, at: iter_file_splice_write+0x257/0xf30 fs/splice.c:635 but task is already holding lock: ffff888148024460 (sb_writers#5){.+.+}-{0:0}, at: __do_splice fs/splice.c:1144 [inline] ffff888148024460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_splice fs/splice.c:1350 [inline] ffff888148024460 (sb_writers#5){.+.+}-{0:0}, at: __se_sys_splice+0x32c/0x430 fs/splice.c:1332 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sb_writers#5){.+.+}-{0:0}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1763 [inline] sb_start_write include/linux/fs.h:1833 [inline] file_start_write+0xc7/0x230 include/linux/fs.h:3040 ovl_write_iter+0x81d/0xdb0 fs/overlayfs/file.c:357 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:2108 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 iter_file_splice_write+0x7c1/0xf30 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 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+0x44/0xae -> #1 (&ovl_i_mutex_key[depth]){+.+.}-{3:3}: lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 down_write+0x97/0x170 kernel/locking/rwsem.c:1406 inode_lock include/linux/fs.h:774 [inline] ovl_write_iter+0x132/0xdb0 fs/overlayfs/file.c:341 do_iter_readv_writev+0x566/0x770 include/linux/fs.h:2108 do_iter_write+0x16c/0x5f0 fs/read_write.c:866 iter_file_splice_write+0x7c1/0xf30 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 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+0x44/0xae -> #0 (&pipe->mutex/1){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 iter_file_splice_write+0x257/0xf30 fs/splice.c:635 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 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+0x44/0xae other info that might help us debug this: Chain exists of: &pipe->mutex/1 --> &ovl_i_mutex_key[depth] --> sb_writers#5 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_writers#5); lock(&ovl_i_mutex_key[depth]); lock(sb_writers#5); lock(&pipe->mutex/1); *** DEADLOCK *** 1 lock held by syz-executor.4/10138: #0: ffff888148024460 (sb_writers#5){.+.+}-{0:0}, at: __do_splice fs/splice.c:1144 [inline] #0: ffff888148024460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_splice fs/splice.c:1350 [inline] #0: ffff888148024460 (sb_writers#5){.+.+}-{0:0}, at: __se_sys_splice+0x32c/0x430 fs/splice.c:1332 stack backtrace: CPU: 1 PID: 10138 Comm: syz-executor.4 Not tainted 5.14.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131 check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174 validate_chain kernel/locking/lockdep.c:3789 [inline] __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625 __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959 __mutex_lock kernel/locking/mutex.c:1104 [inline] mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119 iter_file_splice_write+0x257/0xf30 fs/splice.c:635 do_splice_from fs/splice.c:767 [inline] do_splice+0xe8e/0x17e0 fs/splice.c:1079 __do_splice fs/splice.c:1144 [inline] __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice+0x32c/0x430 fs/splice.c:1332 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+0x44/0xae RIP: 0033:0x4665e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb03032b188 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00000000004bfcc4 R08: 000000000004ffdc R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffee5058def R14: 00007fb03032b300 R15: 0000000000022000