hi all, When one builds with CONFIG_DYNAMIC_DEBUG=y one consumes extra memory for kernel data Ive managed to coax dyndbg into "not needing" about 30KiB in a __dyndbg* section, how can I return it to the kernel ? https://lore.kernel.org/lkml/20210529200029.205306-1-jim.cromie@gmail.com/ b4: dyndbg: 284 modules, 3013 entries and 11360 bytes in ddebug tables, 168728 bytes in __dyndbg section after: dyndbg: 2900 prdebugs in 277 modules, 12 KiB in ddebug tables, 90 KiB in __dyndbg section, 67 KiB in __dyndbg_sites section about 30Kib of the 67 is recoverable patchset, the short version: A- split __dyndbg in 2, isolate repeating module,file,function data. reach by new .site ptr. B- be safe if !.site C- work towards replacing .site with indexing on vectors: __dyndbgs & __dyndbg_sites c1 add ._index c2 use .index to get to __dyndbgs[0] ( then -> sites[._index] ) c3 insert header record at __dyndbgs[0] c4 rework header to differentiate from struct _ddebug, keep .site c5 drop .site, use indirection to get sites[._index] D- split _index into 2 jobs; _back (to [0]) and _map (to [N]) E- find duplicate site recs e1 - use just 1st of duplicate blocks e2 - in modules, move new site recs into front of sites vector e3 - in builtins, pack the whole sites vector, not just within the module-blocks So that leaves about 40% of __dyndbg_sites unneeded. How to return this to free memory ? FWIW, I tried krealloc on a module's chunk of memory (as attached by module:load_info()) it might have worked if that chunk was kallocd separately by elf-loader code. It evidently was not. PS: questions welcome here, reviews probably best at lkml