On Fri, Jul 24, 2020 at 11:17:11AM +0200, Ingo Molnar wrote: > > * Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote: > > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -564,7 +564,7 @@ static void kprobe_optimizer(struct work_struct *work) > > cpus_read_lock(); > > mutex_lock(&text_mutex); > > /* Lock modules while optimizing kprobes */ > > - mutex_lock(&module_mutex); > > + lock_modules(); > > > > /* > > * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) > > @@ -589,7 +589,7 @@ static void kprobe_optimizer(struct work_struct *work) > > /* Step 4: Free cleaned kprobes after quiesence period */ > > do_free_cleaned_kprobes(); > > > > - mutex_unlock(&module_mutex); > > + unlock_modules(); > > mutex_unlock(&text_mutex); > > cpus_read_unlock(); > > BTW., it would be nice to expand on the comments above - exactly which > parts of the modules code is being serialized against and why? > > We already hold the text_mutex here, which should protect against most > kprobes related activities interfering - and it's unclear (to me) > which part of the modules code is being serialized with here, and the > 'lock modules while optimizing kprobes' comments is unhelpful. :-) > > Thanks, > > Ingo AFAIK, only if you need to call find_module(), you ever need to acquire this mutex. 99% of time it is internally taken care by kernel/module.c. I cannot make up any obvious reason to acquire it here. /Jarkko
