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BUG: KCSAN: data-race in read_pages / read_pages

read-write to 0xffff8881358e4980 of 4 bytes by task 26405 on cpu 0:
 read_pages+0x23c/0x530 mm/readahead.c:170
 page_cache_ra_unbounded+0x224/0x2e0
 do_page_cache_ra mm/readahead.c:299 [inline]
 page_cache_ra_order mm/readahead.c:544 [inline]
 ondemand_readahead+0x524/0x690 mm/readahead.c:666
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:715
 filemap_readahead mm/filemap.c:2473 [inline]
 filemap_get_pages+0x397/0xf90 mm/filemap.c:2514
 filemap_read+0x214/0x680 mm/filemap.c:2594
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2784
 ext4_file_read_iter+0x1d8/0x2a0
 call_read_iter include/linux/fs.h:2079 [inline]
 copy_splice_read+0x39f/0x5d0 fs/splice.c:365
 do_splice_read fs/splice.c:984 [inline]
 splice_direct_to_actor+0x288/0x650 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x960 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
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read-write to 0xffff8881358e4980 of 4 bytes by task 26406 on cpu 1:
 read_pages+0x23c/0x530 mm/readahead.c:170
 page_cache_ra_unbounded+0x224/0x2e0
 do_page_cache_ra mm/readahead.c:299 [inline]
 page_cache_ra_order mm/readahead.c:544 [inline]
 ondemand_readahead+0x524/0x690 mm/readahead.c:666
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:715
 filemap_readahead mm/filemap.c:2473 [inline]
 filemap_get_pages+0x397/0xf90 mm/filemap.c:2514
 filemap_read+0x214/0x680 mm/filemap.c:2594
 generic_file_read_iter+0x78/0x330 mm/filemap.c:2784
 ext4_file_read_iter+0x1d8/0x2a0
 call_read_iter include/linux/fs.h:2079 [inline]
 copy_splice_read+0x39f/0x5d0 fs/splice.c:365
 do_splice_read fs/splice.c:984 [inline]
 splice_direct_to_actor+0x288/0x650 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x960 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
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000001a -> 0x00000020

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26406 Comm: syz-executor.3 Not tainted 6.8.0-rc1-syzkaller-00169-gecb1b8288dc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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