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SubjectRe: [PATCH] lib/scatterlist: Fix to calculate the last_pg properly
On Tue, Jan 10, 2023 at 10:01:53AM +0200, Yishai Hadas wrote:
> On 10/01/2023 7:08, Matthew Wilcox wrote:
> > On Mon, Jan 09, 2023 at 04:47:01PM +0200, Yishai Hadas wrote:
> > > if (sgt_append->prv) {
> > > + unsigned long paddr =
> > > + (page_to_pfn(sg_page(sgt_append->prv)) * PAGE_SIZE +
> > 1. page_to_pfn() * PAGE_SIZE is spelled page_to_phys()
> >
> > 2. physical addresses have type phys_addr_t. Oh, wait, paddr isn't a
> > physical address, it's a pfn because you divide by PAGE_SIZE at the end.
> > But you will get truncation on 32-bit, because page_to_pfn() has type
> > unsigned long. Anyway, this shouldn't be called paddr. Maybe last_pfn
> > or something?
> >
> > > + sgt_append->prv->offset + sgt_append->prv->length) /
> > > + PAGE_SIZE;
>
> In this area of the patch I just reverted to what we had in 6.1 [1] where we
> were good.
>
> I can send V1 and replace the 'paddr' to be called 'last_pfn' if it's really
> needed.

Please change it as Matthew describes so it is clearer

Jason

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