Messages in this thread Patch in this message | | | Date | Fri, 12 Jul 2019 16:34:23 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] arm: Extend the check for RAM in /dev/mem |
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On Fri, Jul 12, 2019 at 03:13:38PM +0000, Raslan, KarimAllah wrote: > On Fri, 2019-07-12 at 15:57 +0100, Will Deacon wrote: > > On Fri, Jul 12, 2019 at 12:21:21AM +0200, KarimAllah Ahmed wrote: > > > > > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > > > index 3645f29..cdc3e8e 100644 > > > --- a/arch/arm64/mm/mmu.c > > > +++ b/arch/arm64/mm/mmu.c > > > @@ -78,7 +78,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd) > > > pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > > > unsigned long size, pgprot_t vma_prot) > > > { > > > - if (!pfn_valid(pfn)) > > > + if (!memblock_is_memory(__pfn_to_phys(pfn))) > > > > This looks broken to me, since it will end up returning 'true' for nomap > > memory and we really don't want to map that using writeback attributes. > > True, I will fix this by using memblock_is_map_memory instead. That said, do > you have any concerns about this approach in general?
If you do that, I don't understand why you need the patch at all given our implementation of pfn_valid() in arch/arm64/mm/init.c.
Will
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