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| author |   Carsten Otte <cotte@de.ibm.com> | 2011-12-01 13:32:16 +0100 |
|---|---|---|
| committer |   Martin Schwidefsky <schwidefsky@de.ibm.com> | 2011-12-01 13:32:17 +0100 |
| commit | 7c81878b34dd1b75dec5c8b68951d1439854d358 (patch) | |
| tree | b8b9ad4c00279d8fc0f0402704fc580b1cbc092c /arch/s390 | |
| parent | [S390] ptrace inferior call interactions with TIF_SYSCALL (diff) | |
| download | linux-dev-7c81878b34dd1b75dec5c8b68951d1439854d358.tar.xz linux-dev-7c81878b34dd1b75dec5c8b68951d1439854d358.zip | |
[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 <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/pgtable.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 524d23b8610c..4f289ff0b7fe 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 */ |