syzbot

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BUG: KCSAN: data-race in filemap_read / filemap_read

read to 0xffff888104dba2b0 of 8 bytes by task 452 on cpu 1:
 filemap_read+0x2ae/0x680 mm/filemap.c:2718
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2837
 ext4_file_read_iter+0x1cc/0x290
 call_read_iter include/linux/fs.h:1862 [inline]
 generic_file_splice_read+0xe3/0x290 fs/splice.c:419
 do_splice_to fs/splice.c:902 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:973
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff888104dba2b0 of 8 bytes by task 451 on cpu 0:
 filemap_read+0x466/0x680 mm/filemap.c:2746
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2837
 ext4_file_read_iter+0x1cc/0x290
 call_read_iter include/linux/fs.h:1862 [inline]
 generic_file_splice_read+0xe3/0x290 fs/splice.c:419
 do_splice_to fs/splice.c:902 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:973
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000004000 -> 0x0000000000010000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 451 Comm: syz-executor.2 Not tainted 6.4.0-rc5-syzkaller-00133-g25041a4c02c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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