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BUG: KCSAN: data-race in filemap_read / ondemand_readahead

read to 0xffff88813a24b9b0 of 8 bytes by task 24845 on cpu 0:
 ondemand_readahead+0x5c6/0x6c0 mm/readahead.c:639
 page_cache_sync_ra+0x284/0x2a0 mm/readahead.c:709
 page_cache_sync_readahead include/linux/pagemap.h:1214 [inline]
 filemap_get_pages+0x257/0xea0 mm/filemap.c:2598
 filemap_read+0x223/0x680 mm/filemap.c:2693
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2840
 call_read_iter include/linux/fs.h:1845 [inline]
 generic_file_splice_read+0xe3/0x290 fs/splice.c:402
 do_splice_to fs/splice.c:885 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:956
 do_splice_direct+0x104/0x180 fs/splice.c:1065
 do_sendfile+0x3b8/0x950 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1309
 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 0xffff88813a24b9b0 of 8 bytes by task 24848 on cpu 1:
 filemap_read+0x466/0x680 mm/filemap.c:2749
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2840
 call_read_iter include/linux/fs.h:1845 [inline]
 generic_file_splice_read+0xe3/0x290 fs/splice.c:402
 do_splice_to fs/splice.c:885 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:956
 do_splice_direct+0x104/0x180 fs/splice.c:1065
 do_sendfile+0x3b8/0x950 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1309
 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: 0x000000000000a600 -> 0x000000000000a800

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24848 Comm: syz-executor.1 Not tainted 6.3.0-rc6-syzkaller-00034-ge62252bc55b6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
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