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

write to 0xffff8880268e04d0 of 4 bytes by task 25525 on cpu 1:
 pipe_write+0x3a2/0xd50 fs/pipe.c:505
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6f0/0x7e0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880268e04d0 of 4 bytes by task 25520 on cpu 0:
 ipipe_prep fs/splice.c:1364 [inline]
 splice_pipe_to_pipe fs/splice.c:1443 [inline]
 do_splice+0x1c2/0x10f0 fs/splice.c:1034
 __do_splice fs/splice.c:1137 [inline]
 __do_sys_splice fs/splice.c:1343 [inline]
 __se_sys_splice+0x2a6/0x390 fs/splice.c:1325
 __x64_sys_splice+0x74/0x80 fs/splice.c:1325
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25520 Comm: syz-executor.4 Not tainted 5.11.0-rc6-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: 0 PID: 25520 Comm: syz-executor.4 Not tainted 5.11.0-rc6-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+0x116/0x15d lib/dump_stack.c:120
 panic+0x1e7/0x5fa kernel/panic.c:231
 kcsan_report+0x67b/0x680 kernel/kcsan/report.c:634
 kcsan_setup_watchpoint+0x472/0x4d0 kernel/kcsan/core.c:568
 ipipe_prep fs/splice.c:1364 [inline]
 splice_pipe_to_pipe fs/splice.c:1443 [inline]
 do_splice+0x1c2/0x10f0 fs/splice.c:1034
 __do_splice fs/splice.c:1137 [inline]
 __do_sys_splice fs/splice.c:1343 [inline]
 __se_sys_splice+0x2a6/0x390 fs/splice.c:1325
 __x64_sys_splice+0x74/0x80 fs/splice.c:1325
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x465b09
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:00007fe848bef188 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465b09
RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00000000004b069f R08: 000002000000001c R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffc9cb8c11f R14: 00007fe848bef300 R15: 0000000000022000
Kernel Offset: disabled
Rebooting in 86400 seconds..