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BUG: KCSAN: data-race in ondemand_readahead / ondemand_readahead

write to 0xffff8881321188a4 of 4 bytes by task 25713 on cpu 0:
 ondemand_readahead+0x3d3/0x780 mm/readahead.c:651
 page_cache_sync_ra+0xdc/0xf0 mm/readahead.c:699
 page_cache_sync_readahead include/linux/pagemap.h:1215 [inline]
 filemap_get_pages mm/filemap.c:2566 [inline]
 filemap_read+0x3ef/0x1430 mm/filemap.c:2660
 generic_file_read_iter+0x72/0x320 mm/filemap.c:2806
 ext4_file_read_iter+0x1e9/0x2a0
 call_read_iter include/linux/fs.h:2181 [inline]
 generic_file_splice_read+0xde/0x2b0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x26c/0x620 fs/splice.c:865
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881321188a4 of 4 bytes by task 25693 on cpu 1:
 page_cache_ra_order mm/readahead.c:550 [inline]
 ondemand_readahead+0x572/0x780 mm/readahead.c:672
 page_cache_sync_ra+0xdc/0xf0 mm/readahead.c:699
 page_cache_sync_readahead include/linux/pagemap.h:1215 [inline]
 filemap_get_pages mm/filemap.c:2566 [inline]
 filemap_read+0x3ef/0x1430 mm/filemap.c:2660
 generic_file_read_iter+0x72/0x320 mm/filemap.c:2806
 ext4_file_read_iter+0x1e9/0x2a0
 call_read_iter include/linux/fs.h:2181 [inline]
 generic_file_splice_read+0xde/0x2b0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x26c/0x620 fs/splice.c:865
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000014 -> 0x00000013

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25693 Comm: syz-executor.3 Not tainted 6.0.0-rc2-syzkaller-00054-gc40e8341e3b3-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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