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[184.147.118.108]) by smtp.gmail.com with ESMTPSA id x9sm3701082qtf.76.2021.06.04.08.20.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jun 2021 08:20:50 -0700 (PDT) Date: Fri, 4 Jun 2021 11:20:49 -0400 From: Peter Xu To: Alistair Popple Cc: Balbir Singh , John Hubbard , Andrew Morton , linux-mm@kvack.org, nouveau@lists.freedesktop.org, bskeggs@redhat.com, rcampbell@nvidia.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, hch@infradead.org, jglisse@redhat.com, willy@infradead.org, jgg@nvidia.com, hughd@google.com, Christoph Hellwig Subject: Re: [PATCH v9 07/10] mm: Device exclusive memory access Message-ID: References: <20210524132725.12697-1-apopple@nvidia.com> <3853054.AI2YdRgKcH@nvdebian> <10231977.pWpf7cJbZl@nvdebian> MIME-Version: 1.0 In-Reply-To: <10231977.pWpf7cJbZl@nvdebian> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Stat-Signature: me3wifse1c6x7x8udag458e9m4s69e83 X-Rspamd-Queue-Id: AFC875001704 X-Rspamd-Server: rspam02 Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=UPv924yY; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf01.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=peterx@redhat.com X-HE-Tag: 1622820053-36909 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 Fri, Jun 04, 2021 at 11:07:42AM +1000, Alistair Popple wrote: > On Friday, 4 June 2021 12:47:40 AM AEST Peter Xu wrote: > > External email: Use caution opening links or attachments > > > > On Thu, Jun 03, 2021 at 09:39:32PM +1000, Alistair Popple wrote: > > > Reclaim won't run on the page due to the extra references from the special > > > swap entries. > > > > That sounds reasonable, but I didn't find the point that stops it, probably > > due to my limited knowledge on the reclaim code. Could you elaborate? > > Sure, it isn't immediately obvious but it ends up being detected at the start > of is_page_cache_freeable() in the pageout code: > > > static pageout_t pageout(struct page *page, struct address_space *mapping) > { > > [...] > > if (!is_page_cache_freeable(page)) > return PAGE_KEEP; I did look at pageout() but still missed this small helper indeed (while it's so important to know..), thanks! -- Peter Xu