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Thu, 23 Apr 2020 12:16:03 +0900 (KST) Received: from [10.253.104.82] (unknown [10.253.104.82]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20200423031602epsmtip2f454c065270303101c7eedab570922a6~IVHyfO7At1819118191epsmtip29; Thu, 23 Apr 2020 03:16:02 +0000 (GMT) Subject: Re: [PATCH v2] mm/vmscan: count layzfree pages and fix nr_isolated_* mismatch To: Johannes Weiner Cc: minchan@kernel.org, mgorman@suse.de, m.szyprowski@samsung.com, mina86@mina86.com, shli@fb.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com, ytk.lee@samsung.com From: Jaewon Kim Message-ID: <5EA10872.3010500@samsung.com> Date: Thu, 23 Apr 2020 12:16:02 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <20200422130751.GD358439@cmpxchg.org> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrBJsWRmVeSWpSXmKPExsWy7bCmgW4Jx8I4g2uneC3mrF/DZrF6k69F 9+aZjBaXd81hs7i35j+rxdojd9ktJr97xmix4HgLq8Wyr+/ZLZbt7GexeLye24Hb4/Cb98we E5vfsXvsnHWX3WPTqk42j02fJrF7nJjxm8Vj3Z9XTB59W1Yxemw+Xe3xeZNcAFdUjk1GamJK apFCal5yfkpmXrqtkndwvHO8qZmBoa6hpYW5kkJeYm6qrZKLT4CuW2YO0MFKCmWJOaVAoYDE 4mIlfTubovzSklSFjPziElul1IKUnAJDgwK94sTc4tK8dL3k/FwrQwMDI1OgyoScjIaT39kK tvJX3Jl4nr2BcTFPFyMnh4SAicTFn7OZuhi5OIQEdjBKvL6xiQXC+cQoMfPKcijnG6NE6583 rDAta55uYoRI7GWUmLW+E8p5yyix4sMWZpAqYYEIiW8de8FsEQENiUuLOthAipgFHjJKHHxy gQUkwSagLfF+wSSwsbwCWhIrNq4Fa2ARUJVYs+kCmC0KNGjH3I+MEDWCEidnPgHr5RQwktjz by5YnFlAXqJ562xmkAUSAtPZJW5O+Q51q4vEvqm/mSBsYYlXx7ewQ9hSEp/f7WWDaGhmlHg7 czMjhNPCKHF3Uy8jRJWxRG8PyBkcQCs0Jdbv0ocIK0rs/A2zmU/i3dceVpASCQFeiY42IYgS NYmWZ1+hbpCR+PvvGZTtIfHu+kFWSHDtZJR4M/8e+wRGhVlInpuF5KFZCJsXMDKvYhRLLSjO TU8tNiwwRI7lTYzgVKxluoNxyjmfQ4wCHIxKPLwRigvihFgTy4orcw8xSnAwK4nwbng4L06I NyWxsiq1KD++qDQntfgQoykwvCcyS4km5wPzRF5JvKGpkbGxsYWJmbmZqbGSOO/U6zlxQgLp iSWp2ampBalFMH1MHJxSDYzsknk3NwdrJR1S2u933/pepOHk54bb8qLzbtVJWaw+K8GzUp57 6v5lujwSZdk5pgb7jiYkCxybfCuqT1iyj+ftxFUGE5hq1ruIbpkYMrFKn4lnlf2lL3JyesdO hSvF5z2Xi1h6lfNxrkD27Qr2jTwekRMNA7dNUuCZXijvNnvCnRSZPfU/dyixFGckGmoxFxUn AgAB08d12wMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprKIsWRmVeSWpSXmKPExsWy7bCSvG4xx8I4g/MbeSzmrF/DZrF6k69F 9+aZjBaXd81hs7i35j+rxdojd9ktJr97xmix4HgLq8Wyr+/ZLZbt7GexeLye24Hb4/Cb98we E5vfsXvsnHWX3WPTqk42j02fJrF7nJjxm8Vj3Z9XTB59W1Yxemw+Xe3xeZNcAFcUl01Kak5m WWqRvl0CV0bDye9sBVv5K+5MPM/ewLiYp4uRk0NCwERizdNNjF2MXBxCArsZJQ6tucgGkZCR eHP+KUsXIweQLSxx+HAxRM1rRol5K34ygdQIC0RI3Pp2kR3EFhHQkLi0qIMNomgno0Tz1t1g U5kFHjJKrP0xlQWkik1AW+L9gkmsIDavgJbEio1rmUFsFgFViTWbLoDZokBTV6+7xgxRIyhx cuYTsF5OASOJPf/mMoJcxCygLrF+nhBImFlAHmjXbOYJjIKzkHTMQqiahaRqASPzKkbJ1ILi 3PTcYsMCo7zUcr3ixNzi0rx0veT83E2M4MjS0trBeOJE/CFGAQ5GJR7eCMUFcUKsiWXFlbmH GCU4mJVEeDc8nBcnxJuSWFmVWpQfX1Sak1p8iFGag0VJnFc+/1ikkEB6YklqdmpqQWoRTJaJ g1OqgTHzxfnSzcefFN31uab1Scy2YVfKo8fz5Dje+KX8WHBwluFBvZaegIBNAiw7Gz8URu5K 69otd226z1Ip/e8WH7V3eIYfXt/fEmWjtW/OBav50RGM098XnsnQZFdX+cPzKrv6QBvDG5nC 5U2aLE1xuywenJ08u/PL802ZSqInb999VVqTWn+vr1WJpTgj0VCLuag4EQD8FuNKqAIAAA== X-CMS-MailID: 20200423031603epcas1p23b29e014c3b9182b495bdd368e3b340f X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20200422084832epcas1p333225f9b6a00c9ce36f5f5d63fe6e3bf References: <20200422084815.21913-1-jaewon31.kim@samsung.com> <20200422130751.GD358439@cmpxchg.org> Content-Transfer-Encoding: quoted-printable 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 2020=EB=85=84 04=EC=9B=94 22=EC=9D=BC 22:07, Johannes Weiner wrote: > On Wed, Apr 22, 2020 at 05:48:15PM +0900, Jaewon Kim wrote: >> @@ -1295,11 +1295,15 @@ static unsigned long shrink_page_list(struct l= ist_head *page_list, >> */ >> if (page_mapped(page)) { >> enum ttu_flags flags =3D ttu_flags | TTU_BATCH_FLUSH; >> + bool lazyfree =3D PageAnon(page) && !PageSwapBacked(page); >> =20 >> if (unlikely(PageTransHuge(page))) >> flags |=3D TTU_SPLIT_HUGE_PMD; >> + >> if (!try_to_unmap(page, flags)) { >> stat->nr_unmap_fail +=3D nr_pages; >> + if (lazyfree && PageSwapBacked(page)) > This looks pretty strange, until you remember that try_to_unmap() > could SetPageSwapbacked again. > > This might be more obvious? > > was_swapbacked =3D PageSwapBacked(page); > if (!try_to_unmap(page, flags)) { > stat->nr_unmap_fail +=3D nr_pages; > if (!was_swapbacked && PageSwapBacked(page)) Hello Johannes, thank you for your comment. The name can changed from layzyfree to was_swapbacked. By the way, did you mean removing PageAnon(page), too? It seems to be OK,= though. >> + stat->nr_lazyfree_fail +=3D nr_pages; >> goto activate_locked; > Or at least was_lazyfree. Sorry but I'm confused. I think you meant additional comment to previous your comment rather than you wanted to rename stat->nr_lazyfree_fail to stat->was_lazy= free. > >> @@ -1491,8 +1495,8 @@ unsigned long reclaim_clean_pages_from_list(stru= ct zone *zone, >> .priority =3D DEF_PRIORITY, >> .may_unmap =3D 1, >> }; >> - struct reclaim_stat dummy_stat; >> - unsigned long ret; >> + struct reclaim_stat stat; >> + unsigned long reclaimed; > nr_reclaimed would be better. I will add nr_ prefix on next patch. > > I also prefer keeping dummy_stat, since that's still what it is. This patch uses stat.nr_lazyfree_fail, I do not understand why it is stil= l dummy_stat. If you want, I will keep dummy_stat, though. Thank you Jaewon Kim > >