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Thu, 18 Mar 2021 08:02:19 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:e46c]) by smtp.gmail.com with ESMTPSA id d10sm1947661qko.70.2021.03.18.08.02.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Mar 2021 08:02:18 -0700 (PDT) Date: Thu, 18 Mar 2021 11:02:17 -0400 From: Johannes Weiner To: Michal Hocko Cc: Shakeel Butt , Hugh Dickins , Roman Gushchin , Andrew Morton , Minchan Kim , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Heiko Carstens Subject: Re: [PATCH] memcg: set page->private before calling swap_readpage Message-ID: References: <20210318015959.2986837-1-shakeelb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: DDA896000105 X-Stat-Signature: ujpbfdrrgbhuqpj6p1nwonadm8w44w7b Received-SPF: none (cmpxchg.org>: No applicable sender policy available) receiver=imf25; identity=mailfrom; envelope-from=""; helo=mail-io1-f50.google.com; client-ip=209.85.166.50 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616080059-796770 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 Thu, Mar 18, 2021 at 03:01:25PM +0100, Michal Hocko wrote: > On Wed 17-03-21 18:59:59, Shakeel Butt wrote: > > The function swap_readpage() (and other functions it call) extracts swap > > entry from page->private. However for SWP_SYNCHRONOUS_IO, the kernel > > skips the swapcache and thus we need to manually set the page->private > > with the swap entry before calling swap_readpage(). > > One thing that is not really clear to me is whether/why this is only > needed with your patch. Can you expand a bit on that please? Maybe I am > just missing something obvious but I just do not see any connection. It was always needed, his original patch erroneously removed it.