[v2] PC, KVM, CMA: Fix regression caused by wrong get_order() use

Submitted by Alexey Kardashevskiy on Aug. 14, 2014, 5:03 a.m.

Details

Message ID 1407992587-9164-1-git-send-email-aik@ozlabs.ru
State New
Headers show

Commit Message

Alexey Kardashevskiy Aug. 14, 2014, 5:03 a.m.
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 order_base_2() (round-up version of ilog2).

Suggested-by: Paul Mackerras <paulus@samba.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

Changes:
v2:
* s/ilog2/order_base_2/
* removed cc: <stable@vger.kernel.org> as I got wrong impression that v3.16 is
broken

---
 arch/powerpc/kvm/book3s_hv_builtin.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Aneesh Kumar K.V Aug. 14, 2014, 5:13 a.m.
Alexey Kardashevskiy <aik@ozlabs.ru> writes:

> 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 order_base_2() (round-up version of ilog2).
>
> Suggested-by: Paul Mackerras <paulus@samba.org>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

> ---
>
> Changes:
> v2:
> * s/ilog2/order_base_2/
> * removed cc: <stable@vger.kernel.org> as I got wrong impression that v3.16 is
> broken
>
> ---
>  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..b9615ba 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, order_base_2(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(order_base_2(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, order_base_2(align_pages));
>  }
>  EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
>
> -- 
> 2.0.0

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Alexander Graf Aug. 14, 2014, 1:40 p.m.
On 14.08.14 07:13, Aneesh Kumar K.V wrote:
> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>
>> 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 order_base_2() (round-up version of ilog2).
>>
>> Suggested-by: Paul Mackerras <paulus@samba.org>
>> Cc: Alexander Graf <agraf@suse.de>
>> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

So this affects 3.17?


Alex

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Alexey Kardashevskiy Aug. 15, 2014, 3 a.m.
On 08/14/2014 11:40 PM, Alexander Graf wrote:
> 
> On 14.08.14 07:13, Aneesh Kumar K.V wrote:
>> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>>
>>> 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 order_base_2() (round-up version of ilog2).
>>>
>>> Suggested-by: Paul Mackerras <paulus@samba.org>
>>> Cc: Alexander Graf <agraf@suse.de>
>>> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> 
> So this affects 3.17?

Yes.
Joonsoo Kim Aug. 20, 2014, 2:44 a.m.
On Thu, Aug 14, 2014 at 03:03:07PM +1000, Alexey Kardashevskiy wrote:
> 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 order_base_2() (round-up version of ilog2).
> 
> Suggested-by: Paul Mackerras <paulus@samba.org>
> Cc: Alexander Graf <agraf@suse.de>
> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Sorry for my fault. :(

Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Thanks.
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Patch hide | download patch | download mbox

diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 329d7fd..b9615ba 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, order_base_2(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(order_base_2(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, order_base_2(align_pages));
 }
 EXPORT_SYMBOL_GPL(kvm_alloc_hpt);