syzbot

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BUG: KCSAN: data-race in ext4_setattr / ondemand_readahead

write to 0xffff88812b44db48 of 8 bytes by task 17523 on cpu 1:
 i_size_write include/linux/fs.h:916 [inline]
 ext4_setattr+0xd7f/0xef0 fs/ext4/inode.c:5440
 notify_change+0x8a3/0xac0 fs/attr.c:410
 do_truncate+0xf7/0x140 fs/open.c:64
 handle_truncate fs/namei.c:3084 [inline]
 do_open fs/namei.c:3432 [inline]
 path_openat+0x1925/0x1ec0 fs/namei.c:3561
 do_filp_open+0x105/0x220 fs/namei.c:3588
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1200
 do_sys_open fs/open.c:1216 [inline]
 __do_sys_creat fs/open.c:1290 [inline]
 __se_sys_creat fs/open.c:1284 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1284
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812b44db48 of 8 bytes by task 17465 on cpu 0:
 i_size_read include/linux/fs.h:894 [inline]
 do_page_cache_ra mm/readahead.c:256 [inline]
 ondemand_readahead+0x52e/0x7c0 mm/readahead.c:552
 page_cache_async_ra+0x17e/0x1a0 mm/readahead.c:609
 page_cache_async_readahead include/linux/pagemap.h:906 [inline]
 filemap_readahead mm/filemap.c:2520 [inline]
 filemap_get_pages mm/filemap.c:2561 [inline]
 filemap_read+0x4c0/0x1220 mm/filemap.c:2628
 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2779
 ext4_file_read_iter+0x1db/0x290
 call_read_iter include/linux/fs.h:2157 [inline]
 generic_file_splice_read+0x24f/0x330 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000ffffff0dd4e -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17465 Comm: syz-executor.0 Not tainted 5.15.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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