syzbot

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BUG: KCSAN: data-race in filemap_splice_read / page_cache_sync_ra

write to 0xffff888118807228 of 8 bytes by task 4724 on cpu 0:
 filemap_splice_read+0x47e/0x6b0 mm/filemap.c:3037
 ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26f/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+0x2bb0/0x2ff0 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

read to 0xffff888118807228 of 8 bytes by task 4729 on cpu 1:
 page_cache_sync_ra+0x326/0x6c0 mm/readahead.c:577
 filemap_get_pages+0x2d0/0x1150 mm/filemap.c:2603
 filemap_splice_read+0x333/0x6b0 mm/filemap.c:2991
 ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26f/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+0x2bb0/0x2ff0 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: 0x0000000000007bc0 -> 0x0000000000007bf0

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4729 Comm: syz.2.408 Not tainted 6.16.0-syzkaller-12063-g37816488247d #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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