From: Donet Tom <donettom@linux.ibm.com>
To: Hongfu Li <lihongfu@kylinos.cn>,
jgg@ziepe.ca, leon@kernel.org, akpm@linux-foundation.org,
david@kernel.org, ljs@kernel.org, vbabka@kernel.org,
rppt@kernel.org, surenb@google.com, mhocko@suse.com,
shuah@kernel.org
Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] selftests/mm: Fix mmap() return value check in run_migration_benchmark
Date: Tue, 12 May 2026 18:27:53 +0530 [thread overview]
Message-ID: <6963c69e-5bb3-4ac5-96e4-38bc6085d29e@linux.ibm.com> (raw)
In-Reply-To: <20260512101305.139509-1-lihongfu@kylinos.cn>
On 5/12/26 3:43 PM, Hongfu Li wrote:
> mmap() returns MAP_FAILED on error, not NULL. The current check uses
> !buffer->ptr, which evaluates to false when mmap() fails (since
> MAP_FAILED is (void *)-1, not 0), so the error path is never taken.
>
> Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
LGTM
Reviewed-by: Donet Tom <donettom@linux.ibm.com>
> ---
> tools/testing/selftests/mm/hmm-tests.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
> index 788689497e92..d72adba5c74e 100644
> --- a/tools/testing/selftests/mm/hmm-tests.c
> +++ b/tools/testing/selftests/mm/hmm-tests.c
> @@ -2688,7 +2688,7 @@ static inline int run_migration_benchmark(int fd, int use_thp, size_t buffer_siz
> buffer->ptr = mmap(NULL, buffer_size, PROT_READ | PROT_WRITE,
> MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>
> - if (!buffer->ptr)
> + if (buffer->ptr == MAP_FAILED)
> return -1;
>
> /* Apply THP hint if requested */
next prev parent reply other threads:[~2026-05-12 12:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-12 10:13 [PATCH] selftests/mm: Fix mmap() return value check in run_migration_benchmark Hongfu Li
2026-05-12 10:33 ` David Hildenbrand (Arm)
2026-05-12 11:13 ` Dev Jain
2026-05-12 12:21 ` Mike Rapoport
2026-05-12 12:57 ` Donet Tom [this message]
2026-05-12 14:06 ` Lorenzo Stoakes
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