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

write to 0xffff88809792dc50 of 4 bytes by task 22259 on cpu 0:
 pipe_write+0x3a2/0xbc0 fs/pipe.c:524
 call_write_iter include/linux/fs.h:1882 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x665/0x6f0 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88809792dc50 of 4 bytes by task 22257 on cpu 1:
 ipipe_prep fs/splice.c:1440 [inline]
 splice_pipe_to_pipe fs/splice.c:1519 [inline]
 do_splice+0x1c8/0x10c0 fs/splice.c:1118
 __do_sys_splice fs/splice.c:1419 [inline]
 __se_sys_splice fs/splice.c:1401 [inline]
 __x64_sys_splice+0xf2/0x190 fs/splice.c:1401
 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: 1 PID: 22257 Comm: syz-executor.5 Not tainted 5.9.0-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: 22257 Comm: syz-executor.5 Not tainted 5.9.0-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+0x10f/0x19d lib/dump_stack.c:118
 panic+0x207/0x64a kernel/panic.c:231
 kcsan_report+0x684/0x690 kernel/kcsan/report.c:630
 kcsan_setup_watchpoint+0x41e/0x4a0 kernel/kcsan/core.c:540
 ipipe_prep fs/splice.c:1440 [inline]
 splice_pipe_to_pipe fs/splice.c:1519 [inline]
 do_splice+0x1c8/0x10c0 fs/splice.c:1118
 __do_sys_splice fs/splice.c:1419 [inline]
 __se_sys_splice fs/splice.c:1401 [inline]
 __x64_sys_splice+0xf2/0x190 fs/splice.c:1401
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d4d9
Code: 5d b4 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 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fea0c3e8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 0000000000033880 RCX: 000000000045d4d9
RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000118d0d8 R08: 0001000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118d08c
R13: 00007ffeb751ff6f R14: 00007fea0c3e99c0 R15: 000000000118d08c
Kernel Offset: disabled
Rebooting in 86400 seconds..