[PATCH] lib/test_hmm: Remove set but unused page variable

[PATCH] lib/test_hmm: Remove set but unused page variable

[Alistair Popple]

The HMM selftests use atomic_check_access() to check atomic access to a
page has been revoked. It doesn't matter if the page mapping has been
removed from the mirrored page tables as that also implies atomic access
has been revoked. Therefore remove the unused page variable to fix this
compiler warning:

  lib/test_hmm.c:631:16: warning: variable ‘page’ set but not used [-Wunused-but-set-variable]

Fixes: b659baea7546 ("mm: selftests for exclusive device memory")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
 lib/test_hmm.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index 8c55c4723692..c259842f6d44 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -628,10 +628,8 @@ static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
 
 	for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
 		void *entry;
-		struct page *page;
 
 		entry = xa_load(&dmirror->pt, pfn);
-		page = xa_untag_pointer(entry);
 		if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
 			return -EPERM;
 	}
-- 
2.20.1

Re: [PATCH] lib/test_hmm: Remove set but unused page variable

[Souptick Joarder]

On Tue, Jul 6, 2021 at 8:26 AM Alistair Popple <apopple@nvidia.com> wrote:
>
> The HMM selftests use atomic_check_access() to check atomic access to a
> page has been revoked. It doesn't matter if the page mapping has been
> removed from the mirrored page tables as that also implies atomic access
> has been revoked. Therefore remove the unused page variable to fix this
> compiler warning:
>
>   lib/test_hmm.c:631:16: warning: variable ‘page’ set but not used [-Wunused-but-set-variable]
>
> Fixes: b659baea7546 ("mm: selftests for exclusive device memory")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Reported-by: kernel test robot <oliver.sang@intel.com>
> Reported-by: Yang Yingliang <yangyingliang@huawei.com>
> Signed-off-by: Alistair Popple <apopple@nvidia.com>

Acked-by: Souptick Joarder <jrdr.linux@gmail.com>

> ---
>  lib/test_hmm.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/lib/test_hmm.c b/lib/test_hmm.c
> index 8c55c4723692..c259842f6d44 100644
> --- a/lib/test_hmm.c
> +++ b/lib/test_hmm.c
> @@ -628,10 +628,8 @@ static int dmirror_check_atomic(struct dmirror *dmirror, unsigned long start,
>
>         for (pfn = start >> PAGE_SHIFT; pfn < (end >> PAGE_SHIFT); pfn++) {
>                 void *entry;
> -               struct page *page;
>
>                 entry = xa_load(&dmirror->pt, pfn);
> -               page = xa_untag_pointer(entry);
>                 if (xa_pointer_tag(entry) == DPT_XA_TAG_ATOMIC)
>                         return -EPERM;
>         }
> --
> 2.20.1
>
>