linux-kernel - Re: [PATCH v2 1/8] selftests/mm: Add -Wunreachable-code and fix warnings

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Message-ID: <5e5998c6-1375-4a68-8291-9728eee4bb07@oracle.com>
Date: Thu, 31 Jul 2025 12:32:04 -0400
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka
 <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
        Jason Gunthorpe <jgg@...pe.ca>, John Hubbard <jhubbard@...dia.com>,
        Peter Xu <peterx@...hat.com>, Leon Romanovsky <leon@...nel.org>,
        Zi Yan <ziy@...dia.com>, Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
        Dev Jain <dev.jain@....com>, Barry Song <baohua@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt
 <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-riscv@...ts.infradead.org,
        Shuah Khan <shuah@...nel.org>
Cc: kernel@...labora.com
Subject: Re: [PATCH v2 1/8] selftests/mm: Add -Wunreachable-code and fix
 warnings

On 7/31/25 12:01 PM, Muhammad Usama Anjum wrote:
> Enable -Wunreachable-code flag to catch dead code and fix them.
> 
> 1. Remove the dead code and write a comment instead:
> hmm-tests.c:2033:3: warning: code will never be executed
> [-Wunreachable-code]
>                  perror("Should not reach this\n");
>                  ^~~~~~
> 
> 2. ksft_exit_fail_msg() calls exit(). Remove the dead code.
> split_huge_page_test.c:301:3: warning: code will never be executed
> [-Wunreachable-code]
>                  goto cleanup;
>                  ^~~~~~~~~~~~
> 
> 3. Remove duplicate inline.
> pkey_sighandler_tests.c:44:15: warning: duplicate 'inline' declaration
> specifier [-Wduplicate-decl-specifier]
> static inline __always_inline
> 
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@...labora.com>

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>

> ---
>   tools/testing/selftests/mm/Makefile                | 1 +
>   tools/testing/selftests/mm/hmm-tests.c             | 5 ++---
>   tools/testing/selftests/mm/pkey_sighandler_tests.c | 2 +-
>   tools/testing/selftests/mm/split_huge_page_test.c  | 4 +---
>   4 files changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
> index d13b3cef2a2b2..23d4bf6215465 100644
> --- a/tools/testing/selftests/mm/Makefile
> +++ b/tools/testing/selftests/mm/Makefile
> @@ -34,6 +34,7 @@ endif
>   MAKEFLAGS += --no-builtin-rules
>   
>   CFLAGS = -Wall -O2 -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES)
> +CFLAGS += -Wunreachable-code
>   LDLIBS = -lrt -lpthread -lm
>   
>   # Some distributions (such as Ubuntu) configure GCC so that _FORTIFY_SOURCE is
> diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
> index 141bf63cbe05e..15aadaf24a667 100644
> --- a/tools/testing/selftests/mm/hmm-tests.c
> +++ b/tools/testing/selftests/mm/hmm-tests.c
> @@ -2027,11 +2027,10 @@ TEST_F(hmm, hmm_cow_in_device)
>   	if (pid == -1)
>   		ASSERT_EQ(pid, 0);
>   	if (!pid) {
> -		/* Child process waitd for SIGTERM from the parent. */
> +		/* Child process waits for SIGTERM from the parent. */
>   		while (1) {
>   		}
> -		perror("Should not reach this\n");
> -		exit(0);
> +		/* Should not reach this */
>   	}
>   	/* Parent process writes to COW pages(s) and gets a
>   	 * new copy in system. In case of device private pages,
> diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c
> index b5e076a564c95..302fef54049c8 100644
> --- a/tools/testing/selftests/mm/pkey_sighandler_tests.c
> +++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c
> @@ -41,7 +41,7 @@ static siginfo_t siginfo = {0};
>    * syscall will attempt to access the PLT in order to call a library function
>    * which is protected by MPK 0 which we don't have access to.
>    */
> -static inline __always_inline
> +static __always_inline
>   long syscall_raw(long n, long a1, long a2, long a3, long a4, long a5, long a6)
>   {
>   	unsigned long ret;
> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
> index 05de1fc0005b7..a85b2e393e4e8 100644
> --- a/tools/testing/selftests/mm/split_huge_page_test.c
> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
> @@ -296,10 +296,8 @@ void split_file_backed_thp(int order)
>   		ksft_exit_fail_msg("Unable to create a tmpfs for testing\n");
>   
>   	status = snprintf(testfile, INPUT_MAX, "%s/thp_file", tmpfs_loc);
> -	if (status >= INPUT_MAX) {
> +	if (status >= INPUT_MAX)
>   		ksft_exit_fail_msg("Fail to create file-backed THP split testing file\n");
> -		goto cleanup;
> -	}
>   
>   	fd = open(testfile, O_CREAT|O_RDWR, 0664);
>   	if (fd == -1) {