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Tue, 7 Mar 2023 09:22:33 +0800 Message-ID: <174e75a4-f03c-a542-5f6a-651abb5dec58@huawei.com> Date: Tue, 7 Mar 2023 09:22:33 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; 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: <20230306212727.303846-1-sj@kernel.org> From: Kefeng Wang In-Reply-To: <20230306212727.303846-1-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: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Queue-Id: B051516001E X-Rspamd-Server: rspam01 X-Stat-Signature: 4n6krjwpwn9k4qg91rcoo61h1hu71phx X-HE-Tag: 1678152193-236810 X-HE-Meta: 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 Fa5zXAmA wAYKjeAW+hOfrbHgHjwXr8xcFeZlNyGeIOSXE0lvtrZekB+Tpr4ZlVb34CDzmOIDL3Zjbh8rXELbom7GNpOYtGdPYxS1l2gbqhup62exj3i1RYn06+i3W6BeWjb4tmr1gr8v8xqLzXNZ4x08AX/pVJdpzRPaMLbaauvYrMTkqqX5UJ9BnlWIgi95n1rW9I/atFfvx6EyTcvx4ZCawe9A0L940YIPBlCOyPCkDlgjMU3DHT03xF4ixtfSekc64XbwdcvVB 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 2023/3/7 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.