syzbot

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BUG: KCSAN: data-race in filemap_read / filemap_read

read to 0xffff888106aaad68 of 8 bytes by task 15456 on cpu 0:
 filemap_read+0x6f/0xa00 mm/filemap.c:2685
 generic_file_read_iter+0x79/0x330 mm/filemap.c:2903
 ext4_file_read_iter+0x1cc/0x290 fs/ext4/file.c:-1
 copy_splice_read+0x3c1/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:978 [inline]
 splice_direct_to_actor+0x290/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888106aaad68 of 8 bytes by task 15450 on cpu 1:
 filemap_read+0x974/0xa00 mm/filemap.c:2784
 generic_file_read_iter+0x79/0x330 mm/filemap.c:2903
 ext4_file_read_iter+0x1cc/0x290 fs/ext4/file.c:-1
 copy_splice_read+0x3c1/0x5f0 fs/splice.c:363
 do_splice_read fs/splice.c:978 [inline]
 splice_direct_to_actor+0x290/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000137 -> 0x0000000000000138

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15450 Comm: syz.6.3960 Not tainted 6.16.0-rc2-syzkaller-00045-g4663747812d1 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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