Fixing email address for linux-mm.
On Thu, Jan 25, 2024 at 04:07:50PM +0000, Matthew Wilcox wrote:
> On Thu, Jan 25, 2024 at 10:33:17AM +0000, Eric Dumazet wrote:
> > +++ b/net/ipv4/tcp.c
> > @@ -1786,7 +1786,17 @@ static skb_frag_t *skb_advance_to_frag(struct sk_buff *skb, u32 offset_skb,
> >
> > static bool can_map_frag(const skb_frag_t *frag)
> > {
> > - return skb_frag_size(frag) == PAGE_SIZE && !skb_frag_off(frag);
> > + struct page *page;
> > +
> > + if (skb_frag_size(frag) != PAGE_SIZE || skb_frag_off(frag))
> > + return false;
> > +
> > + page = skb_frag_page(frag);
> > +
> > + if (PageCompound(page) || page->mapping)
> > + return false;
>
> I'm not entirely sure why you're testing PageCompound here. If a driver
> allocates a compound page, we'd still want to be able to insert it,
> right?
>
> I have a feeling that we want to fix this in the VM layer. There are
> some weird places calling vm_insert_page() and we should probably make
> them all fail.
>
> Something like this, perhaps?
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 1a60faad2e49..ae0abab56d38 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1871,6 +1871,10 @@ static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
>
> if (!pte_none(ptep_get(pte)))
> return -EBUSY;
> + if (folio->mapping &&
> + ((addr - vma->vm_start) / PAGE_SIZE + vma->vm_pgoff) !=
> + (folio->index + folio_page_idx(folio, page)))
> + return -EINVAL;
> /* Ok, finally just insert the thing.. */
> folio_get(folio);
> inc_mm_counter(vma->vm_mm, mm_counter_file(folio));
>
