On 9/9/21 10:56, David Hildenbrand wrote: > On 09.09.21 00:42, John Hubbard wrote: >> On 9/7/21 2:56 AM, David Hildenbrand wrote: >> ... >>>> If this can be handled gracefully, then I'd rather go with VM_WARN_ON. >>>> Maybe even WARN_ON_ONCE? >>>> >>> >>> I think either VM_BUG_ON() or VM_WARN_ON() -- compiling the runtime >>> checks out -- should be good >>> enough. >>> >>> I'd just go with VM_BUG_ON(), because anybody messing with >>> __isolate_free_page() should clearly spot >>> that we expect the current handling. But no strong opinion. >>> >> >> If in doubt, WARN*() should be preferred over BUG*(). There's a pretty long >> history of "don't kill the machine unless you have to" emails about this, let >> me dig up one...OK, maybe not the best example, but the tip of the iceberg: > > Please note the subtle difference between BUG_ON and VM_BUG_ON. We expect > VM_BUG_ON to be compiled out on any production system. So it's really only a > mean to identify things that really shouldn't be like that during > debugging/testing. IIRC Fedora used to have CONFIG_DEBUG_VM enabled, did it change? > Using WARN... instead of VM_BUG_ON is even worse for production systems. > There are distros that set panic_on_warn, essentially converting WARN... > into BUG... Uh, does any distro really do that?
