On Mon, 3 Aug 2020, Denis Efremov wrote:
>
>
> On 8/2/20 11:24 PM, Julia Lawall wrote:
> >> +@initialize:python@
> >> +@@
> >> +# low-level memory api
> >> +filter = frozenset(['__vmalloc_area_node'])
> >> +
> >> +def relevant(p):
> >> + return not (filter & {el.current_element for el in p})
> >
> > Is this used?
>
> I'll remove it in v8. Or do you want me to add iterate_dir_item() in the list?
What is that?
>
> >
> > Otherwise, I think it would be good to not warn about a use of kvfree
> > if that use is reachable from a kvmalloc. There seems to be such a false
> > positive in fs/btrfs/send.c, on line 1118.
>
> I don't know how to handle this case without position filter.
> It's too complex. In iterate_dir_item() there is:
> buf = kmalloc(buf_len, GFP_KERNEL);
> while(...) {
> if (...) {
> if (is_vmalloc_addr(buf)) {
> vfree(buf);
> ...
> } else {
> char *tmp = krealloc(buf, ...);
>
> if (!tmp)
> kfree(buf);
> ...
> }
> if (!buf) {
> buf = kvmalloc(buf_len, GFP_KERNEL);
> ...
> }
> }
> }
> kvfree(buf);
>
> Adding "when != kvfree(E)" is not enough:
> * E = \(kvmalloc\|kvzalloc\|kvcalloc\|kvzalloc_node\|kvmalloc_node\|
> * kvmalloc_array\)(...)@k
> ... when != is_vmalloc_addr(E)
> + when != kvfree(E)
> when any
> * \(kfree\|kzfree\|vfree\|vfree_atomic\)(E)@p
Why not just
@ok exists@
position p;
expression E;
@@
E = kvalloc(...)
...
kvfree@p(...)
Probably that is what you mean by a position filter, but why not add a
position filter?
julia
> >
> > It also seems that when there are both a kmalloc and a vmalloc, there is
> > no warning if kfree or vfree is used. Is that intentional?
> >
>
> No, I will try to address it in v8.
>
> Regards,
> Denis
>
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