linux-kernel - [PATCH] PC, KVM, CMA: Fix regression caused by wrong get

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Message-Id: <1407903739-7064-1-git-send-email-aik@ozlabs.ru>
Date:	Wed, 13 Aug 2014 14:22:19 +1000
From:	Alexey Kardashevskiy <aik@...abs.ru>
To:	linuxppc-dev@...ts.ozlabs.org
Cc:	Alexey Kardashevskiy <aik@...abs.ru>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Alexander Graf <agraf@...e.de>, Gleb Natapov <gleb@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Michael Ellerman <mpe@...erman.id.au>, kvm-ppc@...r.kernel.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>, <stable@...r.kernel.org>
Subject: [PATCH] PC, KVM, CMA: Fix regression caused by wrong get_order() use

fc95ca7284bc54953165cba76c3228bd2cdb9591 claims that there is no
functional change but this is not true as it calls get_order() (which
takes bytes) where it should have called ilog2() and the kernel stops
on VM_BUG_ON().

This replaces get_order() with ilog2().

Suggested-by: Paul Mackerras <paulus@...ba.org>
Cc: Alexander Graf <agraf@...e.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: <stable@...r.kernel.org>
Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
---
 arch/powerpc/kvm/book3s_hv_builtin.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 329d7fd..bfe9f01 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -101,7 +101,7 @@ struct kvm_rma_info *kvm_alloc_rma()
 	ri = kmalloc(sizeof(struct kvm_rma_info), GFP_KERNEL);
 	if (!ri)
 		return NULL;
-	page = cma_alloc(kvm_cma, kvm_rma_pages, get_order(kvm_rma_pages));
+	page = cma_alloc(kvm_cma, kvm_rma_pages, ilog2(kvm_rma_pages));
 	if (!page)
 		goto err_out;
 	atomic_set(&ri->use_count, 1);
@@ -135,12 +135,12 @@ struct page *kvm_alloc_hpt(unsigned long nr_pages)
 {
 	unsigned long align_pages = HPT_ALIGN_PAGES;
 
-	VM_BUG_ON(get_order(nr_pages) < KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
+	VM_BUG_ON(ilog2(nr_pages) < KVM_CMA_CHUNK_ORDER - PAGE_SHIFT);
 
 	/* Old CPUs require HPT aligned on a multiple of its size */
 	if (!cpu_has_feature(CPU_FTR_ARCH_206))
 		align_pages = nr_pages;
-	return cma_alloc(kvm_cma, nr_pages, get_order(align_pages));
+	return cma_alloc(kvm_cma, nr_pages, ilog2(align_pages));
 }
 EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
 
-- 
2.0.0

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