syzbot

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BUG: KCSAN: data-race in fat_bmap / generic_file_direct_write

write to 0xffff888141284a00 of 8 bytes by task 6977 on cpu 1:
 i_size_write include/linux/fs.h:932 [inline]
 generic_file_direct_write+0x19d/0x1f0 mm/filemap.c:3894
 __generic_file_write_iter+0xae/0x120 mm/filemap.c:4023
 generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4063
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 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 0xffff888141284a00 of 8 bytes by task 6979 on cpu 0:
 i_size_read include/linux/fs.h:910 [inline]
 is_exceed_eof fs/fat/cache.c:340 [inline]
 fat_bmap+0x1d2/0x290 fs/fat/cache.c:375
 __fat_get_block fs/fat/inode.c:129 [inline]
 fat_get_block+0xd1/0x5e0 fs/fat/inode.c:190
 do_mpage_readpage+0x478/0xd90 fs/mpage.c:234
 mpage_readahead+0x1ad/0x2d0 fs/mpage.c:382
 fat_readahead+0x1c/0x20 fs/fat/inode.c:210
 read_pages+0x9f/0x530 mm/readahead.c:160
 page_cache_ra_unbounded+0x224/0x2e0
 do_page_cache_ra+0xa7/0xc0 mm/readahead.c:299
 ondemand_readahead+0x682/0x690 mm/readahead.c:641
 page_cache_sync_ra+0x27e/0x2a0 mm/readahead.c:695
 page_cache_sync_readahead include/linux/pagemap.h:1293 [inline]
 filemap_get_pages+0x251/0xe90 mm/filemap.c:2556
 filemap_splice_read+0x238/0x7f0 mm/filemap.c:2919
 vfs_splice_read fs/splice.c:993 [inline]
 splice_direct_to_actor+0x28c/0x690 fs/splice.c:1069
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 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: 0x0000000000022c00 -> 0x0000000000023000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6979 Comm: syz-executor.0 Not tainted 6.6.0-rc2-syzkaller-00048-g42dc814987c1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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