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t=1663805759; a=rsa-sha256; cv=fail; b=4p65dW7MLctwUcVUbm17h/J5sWAcUsr9X/a5KFjCt4XL+a+HMQldS1QxPvLRyU4a1CVomj 0BbuiBVpAaVwJ6dRL/U0oDHKdxixAlGdl1FoSzOL+CBN/fSUQxoASgvZK67gX7yFbaG7kC VaSqfc+AnEPxIfj/QUhy0lFW6MQ4ihM= X-Stat-Signature: kfskh8sus1qp49jgbhanaikxo871ytbj X-Rspamd-Queue-Id: 65F0440015 X-Rspam-User: Authentication-Results: imf07.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=Mf3jVVg4; spf=pass (imf07.hostedemail.com: domain of dan.j.williams@intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; arc=reject ("signature check failed: fail, {[1] = sig:microsoft.com:reject}"); dmarc=pass (policy=none) header.from=intel.com X-Rspamd-Server: rspam09 X-HE-Tag: 1663805758-320959 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: Jason Gunthorpe wrote: > On Wed, Sep 21, 2022 at 08:48:22AM -0700, Dan Williams wrote: > > > The fsdax core now manages pgmap references when servicing faults that > > install new mappings, and elevates the page reference until it is > > zapped. It coordinates with the VFS to make sure that all page > > references are dropped before the hosting inode goes out of scope > > (iput_final()). > > > > In order to delete the unnecessary pgmap reference taking in mm/gup.c > > devdax needs to move to the same model. > > I think this patch is more about making devdax and fsdax use the same > set of functions and logic so that when it gets to patch 16/17 devdax > doesn't break. That understanding matches the first paragraph, at > least. > > I would delete the remark about gup since it is really patch 17 that > allows gup to be fixed by making it so that refcount == 0 means not to > look at the pgmap (instead of refcount == 1 as is now) ? Yeah, makes sense.