Re: [next] x86: fs/hugetlbfs/inode.c:673:16: error: variable 'm_index' is uninitialized when used here [-Werror,-Wuninitialized]

From: Nathan Chancellor <nathan@kernel.org>
To: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
	linux-mm <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	open list <linux-kernel@vger.kernel.org>,
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	Muchun Song <songmuchun@bytedance.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	David Hildenbrand <david@redhat.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	James Houghton <jthoughton@google.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Miaohe Lin <linmiaohe@huawei.com>, Michal Hocko <mhocko@suse.com>,
	Mina Almasry <almasrymina@google.com>,
	Naoya Horiguchi <naoya.horiguchi@linux.dev>,
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	llvm@lists.linux.dev
Subject: Re: [next] x86: fs/hugetlbfs/inode.c:673:16: error: variable 'm_index' is uninitialized when used here [-Werror,-Wuninitialized]
Date: Thu, 25 Aug 2022 09:10:07 -0700	[thread overview]
Message-ID: <Ywee393cssPJ07Gr@dev-arch.thelio-3990X> (raw)
In-Reply-To: <CA+G9fYsHVdu0toduQqk6vsR8Z8mOVzZ9-_p3O5fjQ5mOpSxsDA@mail.gmail.com>

Hi Naresh,

On Thu, Aug 25, 2022 at 04:13:30PM +0530, Naresh Kamboju wrote:
> The x86_64 and i386 clang builds failed due to these warnings / errors
> on Linux next-20220825.
> 
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> 
> fs/hugetlbfs/inode.c:673:16: error: variable 'm_index' is
> uninitialized when used here [-Werror,-Wuninitialized]
>                                                 m_start, m_index, truncate_op);
>                                                          ^~~~~~~
> fs/hugetlbfs/inode.c:651:26: note: initialize the variable 'm_index'
> to silence this warning
>         pgoff_t m_start, m_index;
>                                 ^
>                                  = 0
> 1 error generated.

Thank you for the report! Commit fcc0d3d00d74 ("hugetlb: handle truncate
racing with page faults") introduced this warning; the Intel folks
caught this as well:

https://lore.kernel.org/202208251012.g1mOhhxy-lkp@intel.com/

As an aside, can you please update your contact for our mailing list to
llvm@lists.linux.dev? We do not use the Google Groups list anymore.

Cheers,
Nathan