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[2003:d8:2f2d:8e00:a20e:59bc:3c13:4806]) by smtp.gmail.com with ESMTPSA id y6-20020a05600c364600b003fe2a40d287sm2942118wmq.1.2023.08.04.10.56.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Aug 2023 10:56:29 -0700 (PDT) Message-ID: <859496c5-3971-0b65-c297-d29083719a75@redhat.com> Date: Fri, 4 Aug 2023 19:56:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 To: Peter Xu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Linus Torvalds , liubo , Matthew Wilcox , Hugh Dickins , Jason Gunthorpe , John Hubbard , Mel Gorman , Shuah Khan , Paolo Bonzini References: <20230803143208.383663-1-david@redhat.com> <20230803143208.383663-7-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v3 6/7] selftest/mm: ksm_functional_tests: test in mmap_and_merge_range() if anything got merged In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: CC753A0015 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: hrrh6xfrkggupdmhofiyjeg7yupzs45z X-HE-Tag: 1691171793-453602 X-HE-Meta: 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 5Uft3wSg kej+pQ/9EVzbPhyqfWMD6RF5CIEjlzfmpig1k5CSaXI2ebmxy/uvYZwe6Ub89+1tMkYer5aTEs6ZAp5UZD4GvqFW/EbfkspY25sJ4nO1XVEI4Wwq2HRs+is2bwcVPIKG1w4CtTeLDWfI7d67zqU1mbx5Qb+6lfien5QvtP8gefNRj3R+e9Xp1NczDkBX7kJZphxYJ1sz8isKjP4Z6J6CJBJrOfXzQbOcyKI+1ekdO/UX4y6V2f/iN+qzomVokLjc5dStoYkhvNxC2st03yOKcqhi5pLCsBvkpefu5VNCt7JOqzFBYWBd29+mMJJJ9V/u/zHxdkPOgxXn6fNJtBCqeT1YaMq4CPlbL26SmRF3yoDVc691g9JWnfinK9tEMf4eOXQ0tKnI8Lj3Yv5esAw7EVVgMixXvTAAUuqk4NlCQK7si12sCLPmZXoCK9nUhktzIpbd1O6xUKuUhLck= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 03.08.23 21:05, Peter Xu wrote: > On Thu, Aug 03, 2023 at 04:32:07PM +0200, David Hildenbrand wrote: >> Let's extend mmap_and_merge_range() to test if anything in the current >> process was merged. range_maps_duplicates() is too unreliable for that >> use case, so instead look at KSM stats. >> >> Trigger a complete unmerge first, to cleanup the stable tree and >> stabilize accounting of merged pages. >> >> Note that we're using /proc/self/ksm_merging_pages instead of >> /proc/self/ksm_stat, because that one is available in more existing >> kernels. >> >> If /proc/self/ksm_merging_pages can't be opened, we can't perform any >> checks and simply skip them. >> >> We have to special-case the shared zeropage for now. But the only user >> -- test_unmerge_zero_pages() -- performs its own merge checks. >> >> Signed-off-by: David Hildenbrand > Hi Peter, thanks for the review! > Acked-by: Peter Xu > > One nitpick: > >> --- >> .../selftests/mm/ksm_functional_tests.c | 47 +++++++++++++++++++ >> 1 file changed, 47 insertions(+) >> >> diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c >> index 0de9d33cd565..cb63b600cb4f 100644 >> --- a/tools/testing/selftests/mm/ksm_functional_tests.c >> +++ b/tools/testing/selftests/mm/ksm_functional_tests.c >> @@ -30,6 +30,7 @@ >> static int ksm_fd; >> static int ksm_full_scans_fd; >> static int proc_self_ksm_stat_fd; >> +static int proc_self_ksm_merging_pages_fd; >> static int ksm_use_zero_pages_fd; >> static int pagemap_fd; >> static size_t pagesize; >> @@ -88,6 +89,22 @@ static long get_my_ksm_zero_pages(void) >> return my_ksm_zero_pages; >> } >> >> +static long get_my_merging_pages(void) >> +{ >> + char buf[10]; >> + ssize_t ret; >> + >> + if (proc_self_ksm_merging_pages_fd < 0) >> + return proc_self_ksm_merging_pages_fd; > > Better do the fds check all in main(), e.g. not all callers below considers > negative values, so -1 can pass "if (get_my_merging_pages())" etc. The two existing callers should be handling it correctly: if (get_my_merging_pages() > 0) -> fail if (val && !get_my_merging_pages() -> fail Both will pass on negative values, unless I am missing something. I tried to keep the test working also on older kernels where ksm_merging_pages does not exist yet (it's ~1 year old). Anyhow, if you think it's better to make the test fail on these setups, I can change it. -- Cheers, David / dhildenb