From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 11 Mar 2013 16:09:55 +0000 (+0100)
Subject: x86/highmem: add a "already used pte" check
X-Git-Url: https://rtime.felk.cvut.cz/gitweb/zynq/linux.git/commitdiff_plain/ceed7e0a30b0b9de08fb1f9ae8d7bd79ceb48466

x86/highmem: add a "already used pte" check

This is a copy from kmap_atomic_prot().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---

diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 63ced6149745..b2ffa5c7d3d3 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -66,6 +66,8 @@ void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+	WARN_ON(!pte_none(*(kmap_pte - idx)));
+
 #ifdef CONFIG_PREEMPT_RT_FULL
 	current->kmap_pte[type] = pte;
 #endif