On 6/4/2018 5:44 PM, Will Deacon wrote:

On Fri, Jun 01, 2018 at 06:09:18PM +0530, Chintan Pandya wrote:

quoted

Huge mappings have had stability issues due to stale
TLB entry and memory leak issues. Since, those are
addressed in this series of patches, it is now safe
to allow huge mappings.

Signed-off-by: Chintan Pandya <redacted>
---
  arch/arm64/mm/mmu.c | 18 ++----------------
  1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6e7e16c..c65abc4 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c

@@ -934,15 +934,8 @@ int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
  {
  	pgprot_t sect_prot = __pgprot(PUD_TYPE_SECT |
  					pgprot_val(mk_sect_prot(prot)));
-	pud_t new_pud = pfn_pud(__phys_to_pfn(phys), sect_prot);
-
-	/* Only allow permission changes for now */
-	if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)),
-				   pud_val(new_pud)))
-		return 0;

Do you actually need to remove these checks? If we're doing
break-before-make properly, then the check won't fire but it would be
good to keep it there so we can catch misuse of these in future.

In other words, can we drop this patch?

Yes, we don't need this patch as BBM is happening before this. I missed
that. I'll remove this patch in v13.

Will

Chintan
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