syzbot

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BUG: KCSAN: data-race in page_cache_ra_order / page_cache_sync_ra

write to 0xffff8881048a0c9c of 4 bytes by task 13425 on cpu 1:
 page_cache_sync_ra+0x4fd/0x6a0 mm/readahead.c:-1
 filemap_get_pages+0x2d0/0x11c0 mm/filemap.c:2690
 filemap_splice_read+0x3a9/0x740 mm/filemap.c:3079
 ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1086
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 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+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881048a0c9c of 4 bytes by task 13430 on cpu 0:
 page_cache_ra_order+0xad/0x220 mm/readahead.c:536
 page_cache_sync_ra+0x52d/0x6a0 mm/readahead.c:626
 filemap_get_pages+0x2d0/0x11c0 mm/filemap.c:2690
 filemap_splice_read+0x3a9/0x740 mm/filemap.c:3079
 ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:158
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1086
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 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+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000009 -> 0x0000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 13430 Comm: syz.9.3369 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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