On Wed, Apr 19, 2023 at 09:15:11AM +0200, Greg KH wrote: > On Tue, Apr 18, 2023 at 01:46:36PM -0700, Luis Chamberlain wrote: > You get 72 columns for changelog text, so you can use it :) Sure! I forget what the limit is, but now I won't forget, new vimrc settings: set textwidth=100 autocmd FileType gitcommit set textwidth=72 set colorcolumn=+1 > > +config MODULE_AUTOLOAD_SUPRESS_DUPS > > MODULE_DEBUG_DUPLICATE perhaps? It has nothing to do with autoloading > (other than that is what userspace is doing) I refer to module auto-loading as the kernel's use of the *request_module() APIs. This code is used by the module auto-loading request_module() API callers, prior to us even dealing with userspace. > and you aren't suppressing anything except throwing up warnings, right? Actually the code does converge duplicate auto-loading requests into one, but'll just rename to MODULE_DEBUG_AUTOLOAD_DUPS. > > + bool "Debug duplicate modules with auto-loading" > > + help > > + Module autoloading allows in-kernel code to request modules through > > + the *request_module*() API calls. This in turn just calls userspace > > + modprobe. Although modprobe checks to see if a module is already > > + loaded before trying to load a module there is a small time window in > > + which multiple duplicate requests can end up in userspace and multiple > > + modprobe calls race calling finit_module() around the same time for > > + duplicate modules. The finit_module() system call can consume in the > > + worst case more than twice the respective module size in virtual > > + memory for each duplicate module requests. Although duplicate module > > + requests are non-fatal virtual memory is a limited resource and each > > + duplicate module request ends up just wasting virtual memory. > > It's not "wasted", as it is returned when the module is determined to be > a duplicate. Otherwise everyone will want this enabled as they think it > will actually save memory. I'll change the language to be clear the issue is memory pressure early on boot. I'll also add a bit of language to help at least guide people to realize that the real value-add for this, ie, I'll have to mention we suspect issue is udev and not module auto-loading and that this however may still help find a few cases we can optimize for. Luis
