Re: [PATCH v3 2/5] alloc_tag: load module tags into separate contiguous memory

[Suren Baghdasaryan <surenb@google.com>]

On Tue, Oct 15, 2024 at 2:08 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> On Mon, Oct 14, 2024 at 07:10:56PM GMT, Suren Baghdasaryan wrote:
> > On Mon, Oct 14, 2024 at 4:51 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> > >
> > > On Mon, 14 Oct 2024 13:36:43 -0700 Suren Baghdasaryan <surenb@google.com> wrote:
> > >
> > > > When a module gets unloaded there is a possibility that some of the
> > > > allocations it made are still used and therefore the allocation tags
> > > > corresponding to these allocations are still referenced. As such, the
> > > > memory for these tags can't be freed. This is currently handled as an
> > > > abnormal situation and module's data section is not being unloaded.
> > > > To handle this situation without keeping module's data in memory,
> > > > allow codetags with longer lifespan than the module to be loaded into
> > > > their own separate memory. The in-use memory areas and gaps after
> > > > module unloading in this separate memory are tracked using maple trees.
> > > > Allocation tags arrange their separate memory so that it is virtually
> > > > contiguous and that will allow simple allocation tag indexing later on
> > > > in this patchset. The size of this virtually contiguous memory is set
> > > > to store up to 100000 allocation tags.
> > > >
> > > > ...
> > > >
> > > > --- a/kernel/module/main.c
> > > > +++ b/kernel/module/main.c
> > > > @@ -1254,22 +1254,17 @@ static int module_memory_alloc(struct module *mod, enum mod_mem_type type)
> > > >       return 0;
> > > >  }
> > > >
> > > > -static void module_memory_free(struct module *mod, enum mod_mem_type type,
> > > > -                            bool unload_codetags)
> > > > +static void module_memory_free(struct module *mod, enum mod_mem_type type)
> > > >  {
> > > >       struct module_memory *mem = &mod->mem[type];
> > > > -     void *ptr = mem->base;
> > > >
> > > >       if (mem->is_rox)
> > > >               vfree(mem->rw_copy);
> > > >
> > > > -     if (!unload_codetags && mod_mem_type_is_core_data(type))
> > > > -             return;
> > > > -
> > > > -     execmem_free(ptr);
> > > > +     execmem_free(mem->base);
> > > >  }
> > >
> > > The changes around here are dependent upon Mike's "module: make
> > > module_memory_{alloc,free} more self-contained", which is no longer in
> > > mm-unstable.  I assume Mike is working on a v2 so I'll park this series
> > > for now.
> >
> > Looks like the last update on Mike's patchset was back in May. Let me
> > check with Mike if he is planning to get it out soon. I would like my
> > patchset to get into 6.12 if possible.
>
> 6.12 or 6.13?

Right, it's 6.13 at this point.