From bb4b42ce0ca36af8c113587ab64b138b3cf5459c Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Wed, 8 May 2013 15:25:38 +0200 Subject: [PATCH] s390: fix gmap_ipte_notifier vs. software dirty pages On heavy paging load some guest cpus started to loop in gmap_ipte_notify. This was visible as stalled cpus inside the guest. The gmap_ipte_notifier tries to map a user page and then made sure that the pte is valid and writable. Turns out that with the software change bit tracking the pte can become read-only (and only software writable) if the page is clean. Since we loop in this code, the page would stay clean and, therefore, be never writable again. Let us just use fixup_user_fault, that guarantees to call handle_mm_fault. Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky --- arch/s390/mm/pgtable.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 7805ddc..18dc417 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -677,8 +677,7 @@ int gmap_ipte_notify(struct gmap *gmap, unsigned long start, unsigned long len) break; } /* Get the page mapped */ - if (get_user_pages(current, gmap->mm, addr, 1, 1, 0, - NULL, NULL) != 1) { + if (fixup_user_fault(current, gmap->mm, addr, FAULT_FLAG_WRITE)) { rc = -EFAULT; break; } -- 2.7.4