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BUG: KCSAN: data-race in __filemap_add_folio / generic_file_direct_write

read-write to 0xffff88811f8d0910 of 8 bytes by task 19378 on cpu 1:
 __filemap_add_folio+0x385/0x730 mm/filemap.c:904
 filemap_add_folio+0x6f/0x150 mm/filemap.c:939
 page_cache_ra_unbounded+0x15e/0x2e0 mm/readahead.c:251
 do_page_cache_ra mm/readahead.c:300 [inline]
 page_cache_ra_order mm/readahead.c:560 [inline]
 ondemand_readahead+0x550/0x6c0 mm/readahead.c:682
 page_cache_sync_ra+0x284/0x2a0 mm/readahead.c:709
 page_cache_sync_readahead include/linux/pagemap.h:1211 [inline]
 filemap_get_pages+0x257/0xea0 mm/filemap.c:2595
 filemap_read+0x223/0x680 mm/filemap.c:2690
 generic_file_read_iter+0x76/0x320 mm/filemap.c:2837
 call_read_iter include/linux/fs.h:1862 [inline]
 generic_file_splice_read+0xe3/0x290 fs/splice.c:403
 do_splice_to fs/splice.c:886 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:957
 do_splice_direct+0x104/0x180 fs/splice.c:1066
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 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

read to 0xffff88811f8d0910 of 8 bytes by task 19365 on cpu 0:
 generic_file_direct_write+0x289/0x400 mm/filemap.c:3866
 __generic_file_write_iter+0x122/0x290 mm/filemap.c:4007
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4083
 do_iter_write+0x4ae/0x770 fs/read_write.c:860
 vfs_iter_write+0x50/0x70 fs/read_write.c:901
 iter_file_splice_write+0x456/0x7d0 fs/splice.c:779
 do_splice_from fs/splice.c:857 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:1023
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:978
 do_splice_direct+0x104/0x180 fs/splice.c:1066
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 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: 0x000000000000000b -> 0x000000000000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19365 Comm: syz-executor.1 Not tainted 6.3.0-syzkaller-13164-g78b421b6a7c6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
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syz-executor.1: attempt to access beyond end of device
loop1: rw=2049, sector=2048, nr_sectors = 4 limit=2048