From 7c81878b34dd1b75dec5c8b68951d1439854d358 Mon Sep 17 00:00:00 2001 From: Carsten Otte Date: Thu, 1 Dec 2011 13:32:16 +0100 Subject: [PATCH] [S390] fix page change underindication in pgste_update_all This patch makes sure we don't underindicate _PAGE_CHANGED in case we have a race between an operation that changes the page and this code path that hits us between page_get_storage_key and page_set_storage_key. Note that we still have a potential underindication on _PAGE_REFERENCED in the unlikely event that the page was changed but not referenced _and_ someone references the page in the race window. That's not considered to be a problem. Signed-off-by: Carsten Otte Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/pgtable.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 524d23b8610..4f289ff0b7f 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -599,10 +599,10 @@ static inline pgste_t pgste_update_all(pte_t *ptep, pgste_t pgste) skey = page_get_storage_key(address); bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED); /* Clear page changed & referenced bit in the storage key */ - if (bits) { - skey ^= bits; - page_set_storage_key(address, skey, 1); - } + if (bits & _PAGE_CHANGED) + page_set_storage_key(address, skey ^ bits, 1); + else if (bits) + page_reset_referenced(address); /* Transfer page changed & referenced bit to guest bits in pgste */ pgste_val(pgste) |= bits << 48; /* RCP_GR_BIT & RCP_GC_BIT */ /* Get host changed & referenced bits from pgste */ -- 2.41.0