syzbot

==================================================================
BUG: KCSAN: data-race in __splice_from_pipe / do_splice

write to 0xffff888097ca5294 of 4 bytes by task 17252 on cpu 0:
 splice_from_pipe_feed fs/splice.c:527 [inline]
 __splice_from_pipe+0x3e2/0x4a0 fs/splice.c:636
 vmsplice_to_user fs/splice.c:1294 [inline]
 do_vmsplice.part.0+0x1c8/0x210 fs/splice.c:1372
 do_vmsplice fs/splice.c:1366 [inline]
 __do_sys_vmsplice+0x15f/0x1c0 fs/splice.c:1393
 __se_sys_vmsplice fs/splice.c:1375 [inline]
 __x64_sys_vmsplice+0x59/0x70 fs/splice.c:1375
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888097ca5294 of 4 bytes by task 17244 on cpu 1:
 opipe_prep fs/splice.c:1506 [inline]
 splice_pipe_to_pipe fs/splice.c:1553 [inline]
 do_splice+0x1b5/0xc30 fs/splice.c:1141
 __do_sys_splice fs/splice.c:1447 [inline]
 __se_sys_splice fs/splice.c:1427 [inline]
 __x64_sys_splice+0x1fd/0x210 fs/splice.c:1427
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17244 Comm: syz-executor.2 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 17244 Comm: syz-executor.2 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x11d/0x187 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0x1a kernel/kcsan/report.c:626
 kcsan_setup_watchpoint+0x3fb/0x440 kernel/kcsan/core.c:519
 opipe_prep fs/splice.c:1506 [inline]
 splice_pipe_to_pipe fs/splice.c:1553 [inline]
 do_splice+0x1b5/0xc30 fs/splice.c:1141
 __do_sys_splice fs/splice.c:1447 [inline]
 __se_sys_splice fs/splice.c:1427 [inline]
 __x64_sys_splice+0x1fd/0x210 fs/splice.c:1427
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ca59
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb17e4f9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00000000005084a0 RCX: 000000000045ca59
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000078bfa0 R08: 000000000000fffd R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000bcb R14: 00000000004cec7a R15: 00007fb17e4fa6d4
Kernel Offset: disabled
Rebooting in 86400 seconds..