On Sun, Sep 15, 2024 at 01:01:43PM +0100, Lorenzo Stoakes wrote:
> On Sun, Sep 15, 2024 at 01:08:27PM GMT, Dan Carpenter wrote:
> > Hi Linus,
> >
> > Commit 79a61cc3fc04 ("mm: avoid leaving partial pfn mappings around in
> > error case") from Sep 11, 2024 (linux-next), leads to the following
> > Smatch static checker warning:
> >
> > mm/memory.c:2709 remap_pfn_range_notrack()
> > warn: sleeping in atomic context
> >
> > mm/memory.c
> > 2696 int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
> > 2697 unsigned long pfn, unsigned long size, pgprot_t prot)
> > 2698 {
> > 2699 int error = remap_pfn_range_internal(vma, addr, pfn, size, prot);
> > 2700
> > 2701 if (!error)
> > 2702 return 0;
> > 2703
> > 2704 /*
> > 2705 * A partial pfn range mapping is dangerous: it does not
> > 2706 * maintain page reference counts, and callers may free
> > 2707 * pages due to the error. So zap it early.
> > 2708 */
> > --> 2709 zap_page_range_single(vma, addr, size, NULL);
> >
> > The lru_add_drain() function at the start of zap_page_range_single() takes a
> > mutext.
>
> Hm does it? I see a local lock, and some folio batch locking which are
> local locks too?
Ah... No it doesn't. It's the mmu_notifier_invalidate_range_start() which is
a might_sleep() function. Sorry for the confusion.
regards,
dan carpenter
