syzbot

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BUG: KCSAN: data-race in filemap_read / filemap_splice_read

write to 0xffff88811a6f8228 of 8 bytes by task 10061 on cpu 0:
 filemap_splice_read+0x523/0x780 mm/filemap.c:3125
 do_splice_read fs/splice.c:980 [inline]
 splice_direct_to_actor+0x26e/0x670 fs/splice.c:1084
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88811a6f8228 of 8 bytes by task 10066 on cpu 1:
 filemap_read+0x98d/0xa10 mm/filemap.c:2873
 generic_file_read_iter+0x79/0x330 mm/filemap.c:2992
 io_iter_do_read io_uring/rw.c:835 [inline]
 __io_read+0x463/0xc50 io_uring/rw.c:951
 io_read+0x4a/0x190 io_uring/rw.c:1031
 __io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1384
 io_issue_sqe+0x206/0xc00 io_uring/io_uring.c:1407
 io_wq_submit_work+0x5bc/0x830 io_uring/io_uring.c:1519
 io_worker_handle_work+0x41e/0x950 io_uring/io-wq.c:652
 io_wq_worker+0x23d/0x970 io_uring/io-wq.c:706
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00000000000000d8 -> 0x00000000000014f0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10066 Comm: iou-wrk-10063 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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