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bh=qcEpi9Xsu+1gTxbES0/HeqU1vgappATrnUAd8kYmA4U=; b=N/9AsHYZ53IGP4ZWddEoG4q9HDfLFJuJdwnOmQUKZaeUO69YAhK8z7vQr//W3eq17y GLEA0S7Lc163eVr/eF7KzNs0dLlPB4ckO8XrBPadSmc/JpNGQwDSo9XuAaXd/8VnjDV9 yuSnwk+fn8KAupe/R27YhveShpueQQEnzxbyS+ap7bb23jxprf1k9aSXs5xOx0osLyq0 IVMq4acFdwTWbtNEoRGHclyAcEo0KUXzMEVFYqF5VswcB/B4Mb7YiKPbNXXffEg1Urlt lMQfcdgMt5WQLtMPJwRMnNRoz4yxmedN5dMcsInhXV74QwsCf+7/cbR3gYUUt8JE0Odl B1Qw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719371966; x=1719976766; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=qcEpi9Xsu+1gTxbES0/HeqU1vgappATrnUAd8kYmA4U=; b=FP86eC/IbtEzVdcZiFpfsD1z1MEyj4ssb0EawLNAFMZIJT9Ha/hXQmGbVtmZHIowb8 07lTmyi2wky+QqSSwvucjNnQwBwsfMPmUA01B878uZZeu0671d0oviPY4Xi2XR6ieo1x Qru+QwJr9iBLj6sFZZld/df5Zlc93+O2ce00LGkU41iClNLTj3xKY6C+UDNb8VaqBtjw XTCEb7H4iCCixsb7+GN5ryi6sKOSmNAvHxG7SsfuPX3St5Bde2D3abXuj2kgtq/Ebki6 nyCUwJi3mXPoz738AaatvEyRb8S8abcyK4hU+ZWPZlPhrBWXqIvStWvXKhph4U8UUDmK E7Cw== X-Forwarded-Encrypted: i=1; AJvYcCWfmca5XldldFRvnJnC3e/6J8KasQBf1Iyrg9Fz9IdRbkKXeXhwD/7TeEhb/M59i8jIluGTNSwGh8RmjfOOK7guqXg= X-Gm-Message-State: AOJu0YwO6K3Fgdg5Orvau7itCmcAK/RHX62UlRVLSdjHE/1JXIbIlr/c 5QWToNCwbJlfIJbqDY1tMzlwNWa9CApCKFq0A+6osQ+yYo4slYK0rWCIqUhWdww88jeL+HxqDP+ +3DbA0PWTY9yCHbdBghJgrDF3RtqPt7nBmDRL X-Google-Smtp-Source: AGHT+IFLY2qZ3ScXikR8P0OWMEtmq1PJfSmSw962tpdr7XOdzhTxVacIeRIFA9/1ZPYRAeIb5P9js56rVkdjLokuTK4= X-Received: by 2002:a17:906:af97:b0:a6f:5609:9552 with SMTP id a640c23a62f3a-a7245c85b6amr586678266b.10.1719371965815; Tue, 25 Jun 2024 20:19:25 -0700 (PDT) MIME-Version: 1.0 References: <20240619115135.GE2494510@nvidia.com> <4c8b81a0-3a76-4802-875f-f26ff1844955@redhat.com> <8e9436f2-6ebb-4ce1-a44f-2a941d354e2a@redhat.com> <20240621095319587-0700.eberman@hu-eberman-lv.qualcomm.com> <5e14ebf6-2a7f-3828-c3f6-5155026d59ae@google.com> In-Reply-To: <5e14ebf6-2a7f-3828-c3f6-5155026d59ae@google.com> From: Vishal Annapurve Date: Tue, 25 Jun 2024 20:19:12 -0700 Message-ID: Subject: Re: [PATCH RFC 0/5] mm/gup: Introduce exclusive GUP pinning To: David Rientjes Cc: Sean Christopherson , Elliot Berman , Fuad Tabba , David Hildenbrand , Jason Gunthorpe , John Hubbard , Andrew Morton , Shuah Khan , Matthew Wilcox , maz@kernel.org, kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, pbonzini@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: DD5A82000E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: aztdr5egcbjmyd3bqebz1kks9n3kw5za X-HE-Tag: 1719371967-274634 X-HE-Meta: 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 ERQlTDzH guR8thZql2Ek33lJmUrnmPSAT9Wou/C9pz4yKIMH/GMDo040iQiTwTvt34VAF4iXu8/ZjE/6QJ2o+oDmmOw98jyq5opwg0A7mUiVpy11JQXXJNIEA1tOLqsEw/3pNYi/p9br3H1BE5XnhxIhUpTopUB42THWJvUKOQI/4gDvuiWS2k3knG6V97bSKYuelHOvbDvugLaWwRh+jrPRWMwwAxXrpZd4sMacBFzT7+jDjadwDt5u9Dk2dc32ukv6+wc6qHvVMWsPaO6UUYsUwe6PokiKLBw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.002167, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 24, 2024 at 2:50=E2=80=AFPM David Rientjes wrote: > > On Mon, 24 Jun 2024, Sean Christopherson wrote: > > > On Fri, Jun 21, 2024, Elliot Berman wrote: > > > On Fri, Jun 21, 2024 at 11:16:31AM +0100, Fuad Tabba wrote: > > > > On Fri, Jun 21, 2024 at 10:10=E2=80=AFAM David Hildenbrand wrote: > > > > > On 21.06.24 10:54, Fuad Tabba wrote: > > > > > > On Fri, Jun 21, 2024 at 9:44=E2=80=AFAM David Hildenbrand wrote: > > > > > >> > > > > > >>>> Again from that thread, one of most important aspects guest_= memfd is that VMAs > > > > > >>>> are not required. Stating the obvious, lack of VMAs makes i= t really hard to drive > > > > > >>>> swap, reclaim, migration, etc. from code that fundamentally = operates on VMAs. > > > > > >>>> > > > > > >>>> : More broadly, no VMAs are required. The lack of stage-= 1 page tables are nice to > > > > > >>>> : have; the lack of VMAs means that guest_memfd isn't pla= ying second fiddle, e.g. > > > > > >>>> : it's not subject to VMA protections, isn't restricted t= o host mapping size, etc. > > > > > >>>> > > > > > >>>> [1] https://lore.kernel.org/all/Zfmpby6i3PfBEcCV@google.com > > > > > >>>> [2] https://lore.kernel.org/all/Zg3xF7dTtx6hbmZj@google.com > > > > > >>> > > > > > >>> I wonder if it might be more productive to also discuss this = in one of > > > > > >>> the PUCKs, ahead of LPC, in addition to trying to go over thi= s in LPC. > > > > > >> > > > > > >> I don't know in which context you usually discuss that, but I= could > > > > > >> propose that as a topic in the bi-weekly MM meeting. > > > > > >> > > > > > >> This would, of course, be focused on the bigger MM picture: ho= w to mmap, > > > > > >> how how to support huge pages, interaction with page pinning, = ... So > > > > > >> obviously more MM focused once we are in agreement that we wan= t to > > > > > >> support shared memory in guest_memfd and how to make that work= with core-mm. > > > > > >> > > > > > >> Discussing if we want shared memory in guest_memfd might be be= tetr > > > > > >> suited for a different, more CC/KVM specific meeting (likely t= he "PUCKs" > > > > > >> mentioned here?). > > > > > > > > > > > > Sorry, I should have given more context on what a PUCK* is :) I= t's a > > > > > > periodic (almost weekly) upstream call for KVM. > > > > > > > > > > > > [*] https://lore.kernel.org/all/20230512231026.799267-1-seanjc@= google.com/ > > > > > > > > > > > > But yes, having a discussion in one of the mm meetings ahead of= LPC > > > > > > would also be great. When do these meetings usually take place,= to try > > > > > > to coordinate across timezones. > > > > Let's do the MM meeting. As evidenced by the responses, it'll be easie= r to get > > KVM folks to join the MM meeting as opposed to other way around. > > > > > > > It's Wednesday, 9:00 - 10:00am PDT (GMT-7) every second week. > > > > > > > > > > If we're in agreement, we could (assuming there are no other plan= ned > > > > > topics) either use the slot next week (June 26) or the following = one > > > > > (July 10). > > > > > > > > > > Selfish as I am, I would prefer July 10, because I'll be on vacat= ion > > > > > next week and there would be little time to prepare. > > > > > > > > > > @David R., heads up that this might become a topic ("shared and p= rivate > > > > > memory in guest_memfd: mmap, pinning and huge pages"), if people = here > > > > > agree that this is a direction worth heading. > > > > > > > > Thanks for the invite! Tentatively July 10th works for me, but I'd > > > > like to talk to the others who might be interested (pKVM, Gunyah, a= nd > > > > others) to see if that works for them. I'll get back to you shortly= . > > > > > > > > > > I'd like to join too, July 10th at that time works for me. > > > > July 10th works for me too. > > > > Thanks all, and David H for the topic suggestion. Let's tentatively > pencil this in for the Wednesday, July 10th instance at 9am PDT and I'll > follow-up offlist with those will be needed to lead the discussion to mak= e > sure we're on track. I would like to join the call too. Regards, Vishal