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Fri, 16 Jun 2023 06:40:27 +0000 Date: Fri, 16 Jun 2023 08:40:26 +0200 From: Michal Hocko To: =?utf-8?B?6LS65Lit5Z2k?= Cc: minchan@kernel.org, senozhatsky@chromium.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [External] Re: [RFC PATCH 1/3] zram: charge the compressed RAM to the page's memcgroup Message-ID: References: <20230615034830.1361853-1-hezhongkun.hzk@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E9461C0022 X-Stat-Signature: eiepthkj89yjpopknjim8khgu394s7nw X-Rspam-User: X-HE-Tag: 1686897628-94097 X-HE-Meta: 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 pSNS3HyL m8a6GBcx+LrMCZx3qt4MwOdzCH1FmjyI5usZwQe2n49AYrc/+OO1DGnbLS/WHVPkBAOlcnHM87D1V0OAjqUUVtEzFCVFK3h9z2K7OGy/6AlMsLjOySuiQVTWmO/CzfnB2UADwIK2N/VIJOfcoyMspZzQyFiEHCGefPHA3ATbHxa6lhZLlCqeNSDs02WgxDks5cRWuvnwqREDZDY4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri 16-06-23 11:31:18, 贺中坤 wrote: > On Thu, Jun 15, 2023 at 10:21 PM Michal Hocko wrote: > > > > On Thu 15-06-23 22:13:09, 贺中坤 wrote: > > > > This is not really answering my question though. memcg under hard limit > > > > is not really my concern. This is a simpler case. I am not saying it > > > > doesn't need to get addresses but it is the memcg hard limited case that > > > > is much more interested. Because your charges are going to fail very > > > > likely and that would mean that swapout would fail AFAIU. If my > > > > understanding is wrong then it would really help to describe that case > > > > much more in the changelog. > > > > > > > > > > OK, Got it. In many cases I have tested, it will not fail because we did > > > not charge the page directly，but the objects(like slab,compressed page), > > > for the zspage may be shared by any memcg. > > > > That sounds like a broken design to me. > > -- > > Michal Hocko > > SUSE Labs > > I will try more cases in different compression ratios and make sure > that swapout will not fail. I do not think different compression methods will cut it. You essentially need some form of memory reserves - in memcg world pre-charged pool of memory readily available for the swapout. Another way would be to allow the charge to bypass the limit with a guarantee that this will be a temporal breach. -- Michal Hocko SUSE Labs