loop3: detected capacity change from 0 to 1024
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
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BUG: KCSAN: data-race in filemap_splice_read / filemap_splice_read

write to 0xffff888109a06520 of 8 bytes by task 5692 on cpu 0:
 filemap_splice_read+0x504/0x750 mm/filemap.c:3178
 ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:160
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x25d/0x680 fs/splice.c:1077
 do_splice_direct_actor fs/splice.c:1230 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1256
 do_sendfile+0x37d/0x640 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64 fs/read_write.c:1418 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1418
 x64_sys_call+0x1015/0x2550 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888109a06520 of 8 bytes by task 5685 on cpu 1:
 filemap_splice_read+0x504/0x750 mm/filemap.c:3178
 ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:160
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x25d/0x680 fs/splice.c:1077
 do_splice_direct_actor fs/splice.c:1230 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1256
 do_sendfile+0x37d/0x640 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64 fs/read_write.c:1418 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1418
 x64_sys_call+0x1015/0x2550 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000000058f -> 0x0000000000000590

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5685 Comm: syz.3.698 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
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