Hello, syzbot found the following issue on: HEAD commit: 9a9aa07a Add linux-next specific files for 20210504 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=12ec3fa9d00000 kernel config: https://syzkaller.appspot.com/x/.config?x=acf3aa1c9f3e62f8 dashboard link: https://syzkaller.appspot.com/bug?extid=86cae0697c35c6294c32 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+86cae0697c35c6294c32@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 5.12.0-next-20210504-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/12393 is trying to acquire lock: ffff88801f433068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock_nested fs/pipe.c:66 [inline] ffff88801f433068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_lock+0x5a/0x70 fs/pipe.c:74 but task is already holding lock: ffff8881448a8460 (sb_writers#5){.+.+}-{0:0}, at: __do_splice+0x134/0x250 fs/splice.c:1144 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (sb_writers#5){.+.+}-{0:0}: 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] mnt_want_write+0x6e/0x3e0 fs/namespace.c:375 ovl_setattr+0x63/0x860 fs/overlayfs/inode.c:31 notify_change+0xb28/0x10f0 fs/attr.c:398 do_truncate+0x13c/0x200 fs/open.c:64 handle_truncate fs/namei.c:3017 [inline] do_open fs/namei.c:3365 [inline] path_openat+0x20e4/0x27e0 fs/namei.c:3494 do_filp_open+0x190/0x3d0 fs/namei.c:3521 do_sys_openat2+0x16d/0x420 fs/open.c:1187 do_sys_open fs/open.c:1203 [inline] __do_sys_openat fs/open.c:1219 [inline] __se_sys_openat fs/open.c:1214 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1214 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #1 (&ovl_i_mutex_key[depth]){+.+.}-{3:3}: down_write+0x92/0x150 kernel/locking/rwsem.c:1406 inode_lock include/linux/fs.h:774 [inline] ovl_write_iter+0x17d/0x17f0 fs/overlayfs/file.c:341 call_write_iter include/linux/fs.h:2114 [inline] do_iter_readv_writev+0x46f/0x740 fs/read_write.c:740 do_iter_write+0x188/0x670 fs/read_write.c:866 vfs_iter_write+0x70/0xa0 fs/read_write.c:907 iter_file_splice_write+0x723/0xc70 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] do_splice+0xb7e/0x1940 fs/splice.c:1079 __do_splice+0x134/0x250 fs/splice.c:1144 __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice fs/splice.c:1332 [inline] __x64_sys_splice+0x198/0x250 fs/splice.c:1332 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae -> #0 (&pipe->mutex/1){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 pipe_lock_nested fs/pipe.c:66 [inline] pipe_lock+0x5a/0x70 fs/pipe.c:74 iter_file_splice_write+0x183/0xc70 fs/splice.c:635 do_splice_from fs/splice.c:767 [inline] do_splice+0xb7e/0x1940 fs/splice.c:1079 __do_splice+0x134/0x250 fs/splice.c:1144 __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice fs/splice.c:1332 [inline] __x64_sys_splice+0x198/0x250 fs/splice.c:1332 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 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.4/12393: #0: ffff8881448a8460 (sb_writers#5){.+.+}-{0:0}, at: __do_splice+0x134/0x250 fs/splice.c:1144 stack backtrace: CPU: 0 PID: 12393 Comm: syz-executor.4 Not tainted 5.12.0-next-20210504-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2129 check_prev_add kernel/locking/lockdep.c:2938 [inline] check_prevs_add kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3676 [inline] __lock_acquire+0x2a17/0x5230 kernel/locking/lockdep.c:4902 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477 __mutex_lock_common kernel/locking/mutex.c:949 [inline] __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096 pipe_lock_nested fs/pipe.c:66 [inline] pipe_lock+0x5a/0x70 fs/pipe.c:74 iter_file_splice_write+0x183/0xc70 fs/splice.c:635 do_splice_from fs/splice.c:767 [inline] do_splice+0xb7e/0x1940 fs/splice.c:1079 __do_splice+0x134/0x250 fs/splice.c:1144 __do_sys_splice fs/splice.c:1350 [inline] __se_sys_splice fs/splice.c:1332 [inline] __x64_sys_splice+0x198/0x250 fs/splice.c:1332 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 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:00007fd13741d188 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9 RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00000000004bfce1 R08: 00000000088000cc R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffcaf06e7ef R14: 00007fd13741d300 R15: 0000000000022000 --- This report is generated by a bot. 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