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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [PATCH v2 2/3] mm/damon/paddr: minor refactor of damon_pa_young() Content-Language: en-US To: SeongJae Park CC: Andrew Morton , , , References: <20230307180023.152415-1-sj@kernel.org> From: Kefeng Wang In-Reply-To: <20230307180023.152415-1-sj@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 24555A000B X-Rspam-User: X-Stat-Signature: 48oyz6dx513fgpe1fbf6hhiusu1ee3m7 X-HE-Tag: 1678237393-149508 X-HE-Meta: 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 spdNObWJ nyCJYlyPPO9X5akPcJNAyk00GUV8FCYw5nuadntYV1Y+VZoqmATNo6ny6oN4Z38hFVOHWA+B2ZXVREkS35Qq0CxkwoT3gvOCb7BdXPpnNKBpEdCHeq5rGeDqFqWn69pU9zkxT1lNsS4TjdZRJWNVNEvWVsoF+0cvzTLsUQhxHcV4fM3m4J217/BnCXJ4LMaSEVDOf8+/0zdiRAAEYI66INrv8pydZgSu6KzCJcRnLJGdDsBi8asxFqfGQQQ== 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 2023/3/8 2:00, SeongJae Park wrote: > On Tue, 7 Mar 2023 09:22:33 +0800 Kefeng Wang wrote: > >> >> >> On 2023/3/7 5:27, SeongJae Park wrote: >>> Hi Kefeng, >>> >>> On Mon, 6 Mar 2023 09:56:49 +0800 Kefeng Wang wrote: >>> >>>> >>>> >>>> On 2023/3/6 9:10, Kefeng Wang wrote: >>>>> >>>>> >>>>> On 2023/3/4 2:39, SeongJae Park wrote: >>>>>> Hi Kefeng, >>>>>> >>>>>> On Fri, 3 Mar 2023 16:43:42 +0800 Kefeng Wang >>>>>> wrote: >>>>>> >>>>>>> Omit three lines by unified folio_put(), and make code more clear. >>>>>>> >>>>>>> Signed-off-by: Kefeng Wang >>>>>>> --- >>>>>>> mm/damon/paddr.c | 11 ++++------- >>>>>>> 1 file changed, 4 insertions(+), 7 deletions(-) >>>>>>> >>>>>>> diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c >>>>>>> index 3fda00a0f786..2ef9db0189ca 100644 >>>>>>> --- a/mm/damon/paddr.c >>>>>>> +++ b/mm/damon/paddr.c >>>>>>> @@ -130,24 +130,21 @@ static bool damon_pa_young(unsigned long paddr, >>>>>>> unsigned long *folio_sz) >>>>>>> accessed = false; >>>>>>> else >>>>>>> accessed = true; >>>>>>> - folio_put(folio); >>>>>>> goto out; >>>>>> >>>>>> Because you moved 'out' label to not include *folio_sz setting, >>>>>> folio_sz will >>>>>> not set in this case. It should be set. >>>>> oh, it should be fixed. >>>>>> >>>>>>> } >>>>>>> need_lock = !folio_test_anon(folio) || folio_test_ksm(folio); >>>>>>> - if (need_lock && !folio_trylock(folio)) { >>>>>>> - folio_put(folio); >>>>>>> - return false; >>>>>>> - } >>>> >>>> Hi SJ, apart from above issue, it looks that this branch need the >>>> folio_size() setting, right? >>> >>> folio_sz is effectively used by caller of damon_pa_young() only if this >>> function returns true, so this branch doesn't need to set folio_sz. >> >> __damon_pa_check_access() store last_addr, last_accessed and >> last_folio_sz, even damon_pa_young() return false, the following check >> still use last_folio_sz, >> >> ALIGN_DOWN(last_addr, last_folio_sz) == ALIGN_DOWN(r->sampling_addr, >> last_folio_sz) >> >> but last_folio_sz is not up to date, so I think it need to update, and >> update last_folio_sz is harmless, which could let's unify the return >> path, correct me if I am wrong. > > Ah, you're right. Thank you for kind explanation. I was out of my mind for > some reason. Maybe we could just do 'goto out' in the branch. Yes, will update this patchset with this change. > > > Thanks, > SJ