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[142.162.113.129]) by smtp.gmail.com with ESMTPSA id e7-20020ac85987000000b002e1b7fa2201sm390829qte.56.2022.03.23.10.04.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Mar 2022 10:04:05 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1nX4Oy-004y0H-9Z; Wed, 23 Mar 2022 14:04:04 -0300 Date: Wed, 23 Mar 2022 14:04:04 -0300 From: Jason Gunthorpe To: Michal Hocko Cc: Juergen Gross , linux-mm@kvack.org, lkml , Andrew Morton , "xen-devel@lists.xenproject.org" , Jerome Glisse Subject: Re: blocking vs. non-blocking mmu notifiers Message-ID: <20220323170404.GK64706@ziepe.ca> References: <8e8ec786-74db-157b-a290-b1537941e91d@suse.com> <20220323163146.GI64706@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: qphmoikcncnq8yem7f85o691yoobpb6z Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=kNJF0xfm; spf=pass (imf12.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.160.172 as permitted sender) smtp.mailfrom=jgg@ziepe.ca; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B13BF40061 X-HE-Tag: 1648055046-723174 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 Wed, Mar 23, 2022 at 05:49:43PM +0100, Michal Hocko wrote: > > The bug here is that prior to commit a81461b0546c ("xen/gntdev: update > > to new mmu_notifier semantic") wired the mn_invl_range_start() which > > takes a mutex to invalidate_page, which is defined to run in an atomic > > context. > > Yeah, we have already identified that but quickly realized that the > whole mmu notifier overhaul which this fix depends on would be no no for > backporting to our older code base. So we are trying to find our way > around that. IMHO you don't need everything, just commit 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic v2") which adds the missing start/end outside the lock for the page callbacks. Then you can take safely a8146 into gntdev. Jason