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b=Fq45RAyfqPyZhSNjubD5Vk0QTJAji108yWWmRtTHXhBeBGa6SNTNhSQfa/8ImIA5t PBbwVa0LSavhZMqUNLMp6HxVMCoN3UPaxbLk6lZn0HwvyQ2KyC95N9kTxeTLAHthg+ wVfMR2v0jA4jXxMDSar8TIz74Q8xSFRAil/h3g523HQ/JC0PhJxRGKAp3/Th2ocn7V zpWDIsOR/NH4nJhehVMK1x2osOI+N4vj4skpuO0lVLF6XOdeYs08ieKPBBA0VrfWXt YGu/Ao9/N00IOwjfDwDSTGmJNn3ZB4M7VSO6153nvheEa7+3Irz6X55p3gAO/kxNb7 VKjwk9lyc3CUg== Message-ID: <5684cab6-d5a6-4de9-9545-f8cae775d825@kernel.org> Date: Wed, 1 Apr 2026 16:39:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 11/13] selftests/mm: fix double increment in linked list cleanup in compaction_test To: Sayali Patil , Andrew Morton , Shuah Khan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Ritesh Harjani Cc: Zi Yan , Michal Hocko , Oscar Salvador , Lorenzo Stoakes , Dev Jain , Liam.Howlett@oracle.com, linuxppc-dev@lists.ozlabs.org, Venkat Rao Bagalkote References: <4c47a2ebbc41f90c7a0cb3f8b34106b2b64296f6.1774591179.git.sayalip@linux.ibm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D540C80014 X-Stat-Signature: 68t78p8uh88dw5e683pxe5c3m7fb9nfk X-Rspam-User: X-HE-Tag: 1775054391-130259 X-HE-Meta: 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 etfrceK7 kOov4kBLIy+ajyWLJcP9EGXq6slai/eE1OCnvbQCnqSY4P0W3FK9knGvO/Xq6toItcqi06a9caDnV+qH+OFkwGf3MSatn/peQJDBgb+O0Pi5U0F5hzgVHEy5GLaQFyRlg4MU01KKzcNmhD2YuMges42yFvl2WQSXz8l+FtDD/EzjZJ/x0SI6pRqBlfBdCPJ9BgRmdCp7C5Kv9/ddBzKybOfsEhaM11vKvDedXGe7W/ThCuGXEHwHl7YoKS0nGgeaZvo1WQ/rSZ+z2/AdA1T0TPefCevYHbjZF7+cq3xOQKe+LlvUn9sKRoM/zLQ8qfTTmZUZhduBGufCFrrNjCW2tl3X4mR3rkWgmkgTrtTxtaY9AwukQflXTV5MlTh3CVGTxRK4n1uLlnDsejujgopp24AYuXDOVLTqjvPkCBxIV/EHdiebgsF74mbHcefMW+Qy5NB4+hp+eE8WSQBSFe+xYjmGFeV1X2P6O410K Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/1/26 16:32, Sayali Patil wrote: > > On 27/03/26 12:46, Sayali Patil wrote: >> The cleanup loop of allocated memory currently uses: >> >>      for (entry = list; entry != NULL; entry = entry->next) { >>          munmap(entry->map, MAP_SIZE); >>          if (!entry->next) >>              break; >>          entry = entry->next; >>      } >> >> The inner entry = entry->next causes the loop to skip every >> other node, resulting in only half of the mapped regions being >> unmapped. >> >> Remove the redundant increment to ensure every entry is visited >> and unmapped during cleanup. >> >> Fixes: bd67d5c15cc1 ("Test compaction of mlocked memory") >> Reviewed-by: Zi Yan >> Acked-by: David Hildenbrand (Arm) >> Tested-by: Venkat Rao Bagalkote >> Signed-off-by: Sayali Patil >> --- >>   tools/testing/selftests/mm/compaction_test.c | 3 --- >>   1 file changed, 3 deletions(-) >> >> diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/ >> testing/selftests/mm/compaction_test.c >> index 30209c40b697..f73930706bd0 100644 >> --- a/tools/testing/selftests/mm/compaction_test.c >> +++ b/tools/testing/selftests/mm/compaction_test.c >> @@ -263,9 +263,6 @@ int main(int argc, char **argv) >>         for (entry = list; entry != NULL; entry = entry->next) { >>           munmap(entry->map, MAP_SIZE); >> -        if (!entry->next) >> -            break; >> -        entry = entry->next; >>       } >>         if (check_compaction(mem_free, hugepage_size, > > Sorry, this change is not valid. > > The goal of this test is to verify the kernel’s ability to compact > unevictable (MAP_LOCKED) pages. The loop is intentionally written to > unmap every other chunk, thereby creating fragmentation with locked pages > before check_compaction() is invoked. > > With the proposed change (removing the double increment), the loop ends up > unmapping all allocated locked pages instead of leaving a fragmented > pattern. This results in memory being effectively unfragmented. Ahhh, we should really make that clearer in a comment. I missed it myself :( -- Cheers, David