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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=gV7TN+Dbz5tzaOrAbCMWHlB+ykfhxbyPEdM4wcjGYq+0I1X2m8RQcA7h/EnzXTodh shob5b98AgeVYcZX7fZWcMf6PGfj7nb0xTIc/7Y+kJAluCLYK6muaymcTD0KUEIcvS /vTSpdtMRdxyAQJQtmQ1brWsFwyRQPX10X+gxOYc= Message-ID: Date: Tue, 12 May 2026 16:43:15 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/mm: Fix mmap() return value check in run_migration_benchmark To: Hongfu Li , 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 References: <20260512101305.139509-1-lihongfu@kylinos.cn> Content-Language: en-US From: Dev Jain In-Reply-To: <20260512101305.139509-1-lihongfu@kylinos.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: A95372000C X-Stat-Signature: t6jd4yq7tqxogcbjbyhffj7unr6wbmx4 X-Rspam-User: X-HE-Tag: 1778584404-314650 X-HE-Meta: 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 YJcMP31h 4Y0nML6y4W7YhFMmxy0iyaCWiDlewkXaFLMWH7UdRGWIC/9B5jtdQrYbA5UJ7id7UUjJLQiE+jfgbYFxqE248VO0yLyhDC7cMnfui2b5nZ5dgefeQ+MqgcF4fa+V+3ALe5q7jyY9IIk4S7ni+yXSUuXoo7wuOkTigfBEQCAlRmgzYRT3IElF4Q+4GmE6z/sSyIGh+6BoNTK+6OcBisZQuGd6AvLmRyrZG8FAgap3MYoWVCY699GEqJ4k2Ni8J6BE9xqxq/38enHN+vjNwG5GBmonr7Gta3OcD0LYffdvG4l0MvHKU1t1zaYc4PEKXuekEDIeZf4At5crurBh2TE3hcwBRPA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12/05/26 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 > --- Reviewed-by: Dev Jain > 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 */