Question

# cachestat
Counting cache functions... Output every 1 seconds.
/bin/cachestat: line 111: printf: write error: Invalid argument
ERROR: tracing these four kernel functions: mark_page_accessed, mark_buffer_dirty, add_to_page_cache_lru and account_page_dirtied (unknown kernel version?). Exiting.

Answer

# echo "account_page_dirtied" >> set_ftrace_filter
sh: write error: Invalid argument

git log -p mm/page-writeback.c

Downgrade to linux-4.19.302 works