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

2014-08-13 Thread Aneesh Kumar K.V
Alexey Kardashevskiy  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 ilog2().

Should we round it up ? ie, ilog2(kvm_rma_pages - 1) + 1 ?

>
> Suggested-by: Paul Mackerras 
> Cc: Alexander Graf 
> Cc: Aneesh Kumar K.V 
> Cc: Joonsoo Kim 
> Cc: Benjamin Herrenschmidt 
> Cc: 

Why stable ? We merged it this merge window.

> Signed-off-by: Alexey Kardashevskiy 
> ---
>  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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[PATCH] PC, KVM, CMA: Fix regression caused by wrong get_order() use

2014-08-12 Thread Alexey Kardashevskiy
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 
Cc: Alexander Graf 
Cc: Aneesh Kumar K.V 
Cc: Joonsoo Kim 
Cc: Benjamin Herrenschmidt 
Cc: 
Signed-off-by: Alexey Kardashevskiy 
---
 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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