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Tue, 7 Jan 2020 12:29:18 +1100 (AEDT) Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 06 Jan 2020 17:28:25 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 06 Jan 2020 17:29:12 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 06 Jan 2020 17:29:12 -0800 Received: from [10.2.162.105] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 7 Jan 2020 01:29:10 +0000 Subject: Re: [PATCH v11 00/25] mm/gup: track dma-pinned pages: FOLL_PIN To: Jan Kara References: <20191219132607.GA410823@unreal> <20191219210743.GN17227@ziepe.ca> <20191220182939.GA10944@unreal> <1001a5fc-a71d-9c0f-1090-546c4913d8a2@nvidia.com> <20191222132357.GF13335@unreal> <49d57efe-85e1-6910-baf5-c18df1382206@nvidia.com> <20191225052612.GA212002@unreal> <612aa292-ec45-295c-b56c-c622876620fa@nvidia.com> <20200106090147.GA9176@quack2.suse.cz> From: John Hubbard X-Nvconfidentiality: public Message-ID: <9128d033-530f-468c-e076-05a9f845c72f@nvidia.com> Date: Mon, 6 Jan 2020 17:26:16 -0800 User-Agent: Mozilla/5.0 (X11; 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Miller" , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 1/6/20 1:01 AM, Jan Kara wrote: ... >> Also, looking ahead: >> >> a) if the problem disappears with the latest above test, then we likely have >> a huge page refcount overflow, and there are a couple of different ways to >> fix it. >> >> b) if it still reproduces with the above, then it's some other random mistake, >> and in that case I'd be inclined to do a sort of guided (or classic, unguided) >> git bisect of the series. Because it could be any of several patches. >> >> If that's too much trouble, then I'd have to fall back to submitting a few >> patches at a time and working my way up to the tracking patch... > > It could also be that an ordinary page reference is dropped with 'unpin' > thus underflowing the page refcount... > > Honza > Yes. And, I think I'm about out of time for this release cycle, so I'm probably going to submit the prerequisite patches (patches 1-10, or more boldly, 1-22), for candidates for 5.6. thanks, -- John Hubbard NVIDIA