From: Sebastian Andrzej Siewior Date: Mon, 11 Mar 2013 17:09:55 +0100 Subject: [PATCH 216/353] x86/highmem: Add a "already used pte" check Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=8d135b937084351cf2c7a207269c717c6430da47 This is a copy from kmap_atomic_prot(). Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/mm/iomap_32.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c index d5a48210d0f6..c0ec8d430c02 100644 --- a/arch/x86/mm/iomap_32.c +++ b/arch/x86/mm/iomap_32.c @@ -69,6 +69,8 @@ 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