Re: [PATCH v1 08/16] kmsan: convert kmsan_handle_dma to use physical addresses

[Jason Gunthorpe <jgg@xxxxxxxxxx>]

On Wed, Aug 13, 2025 at 06:07:18PM +0300, Leon Romanovsky wrote:
> > >  /* Helper function to handle DMA data transfers. */
> > > -void kmsan_handle_dma(struct page *page, size_t offset, size_t size,
> > > +void kmsan_handle_dma(phys_addr_t phys, size_t size,
> > >                 enum dma_data_direction dir)
> > >  {
> > >   u64 page_offset, to_go, addr;
> > > + struct page *page;
> > > + void *kaddr;
> > >  
> > > - if (PageHighMem(page))
> > > + if (!pfn_valid(PHYS_PFN(phys)))
> > >           return;
> > 
> > Not needed, the caller must pass in a phys that is kmap
> > compatible. Maybe just leave a comment. FWIW today this is also not
> > checking for P2P or DEVICE non-kmap struct pages either, so it should
> > be fine without checks.
> 
> It is not true as we will call to kmsan_handle_dma() unconditionally in
> dma_map_phys(). The reason to it is that kmsan_handle_dma() is guarded
> with debug kconfig options and cost of pfn_valid() can be accommodated
> in that case. It gives more clean DMA code.

Then check attrs here, not pfn_valid.

> So let's keep this patch as is.

Still need to fix the remarks you clipped, do not check PageHighMem
just call kmap_local_pfn(). All thie PageHighMem stuff is new to this
patch and should not be here, it is the wrong way to use highmem.

Jason