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BUG: KCSAN: data-race in ondemand_readahead / ondemand_readahead

write to 0xffff8881088a2b78 of 8 bytes by task 6816 on cpu 1:
 ondemand_readahead+0x223/0x6b0 mm/readahead.c:646
 page_cache_sync_ra+0xe0/0xf0 mm/readahead.c:696
 page_cache_sync_readahead include/linux/pagemap.h:1306 [inline]
 filemap_get_pages+0x252/0xfb0 mm/filemap.c:2529
 filemap_splice_read+0x360/0x920 mm/filemap.c:2894
 ext4_file_splice_read+0x95/0xc0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x26c/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3ab/0x960 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881088a2b78 of 8 bytes by task 6809 on cpu 0:
 ondemand_readahead+0x133/0x6b0 mm/readahead.c:581
 page_cache_sync_ra+0xe0/0xf0 mm/readahead.c:696
 page_cache_sync_readahead include/linux/pagemap.h:1306 [inline]
 filemap_get_pages+0x252/0xfb0 mm/filemap.c:2529
 filemap_splice_read+0x360/0x920 mm/filemap.c:2894
 ext4_file_splice_read+0x95/0xc0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x26c/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3ab/0x960 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000009 -> 0x000000000000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6809 Comm: syz.3.1117 Not tainted 6.10.0-rc5-syzkaller-00155-g66e55ff12e73 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
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