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[213.151.95.130]) by smtp.gmail.com with ESMTPSA id m7sm18599014wma.39.2020.01.27.05.47.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jan 2020 05:47:03 -0800 (PST) Date: Mon, 27 Jan 2020 14:47:02 +0100 From: Michal Hocko To: Dan Williams Cc: David Hildenbrand , Andrew Morton , stable , Vishal Verma , Pavel Tatashin , Dave Hansen , Linux MM , Linux Kernel Mailing List Subject: Re: [PATCH] mm/memory_hotplug: Fix remove_memory() lockdep splat Message-ID: <20200127134702.GJ1183@dhcp22.suse.cz> References: <4d0334e2-c4e7-6d3f-99ba-2ca0495e1549@redhat.com> <64902066-51dd-9693-53fc-4a5975c58409@redhat.com> <516aa930-9b64-b377-557c-5413ed9fe336@redhat.com> <20200124124512.GT29276@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 24-01-20 10:04:52, Dan Williams wrote: > On Fri, Jan 24, 2020 at 4:56 AM Michal Hocko wrote: > > > > On Fri 10-01-20 13:27:24, Dan Williams wrote: > > > On Fri, Jan 10, 2020 at 9:42 AM David Hildenbrand wrote: > > [...] > > > > For your reference (roughly 5 months ago, so not that old) > > > > > > > > https://lkml.kernel.org/r/20190724143017.12841-1-david@redhat.com > > > > > > Oh, now I see the problem. You need to add that lock so far away from > > > the __add_memory() to avoid lock inversion problems with the > > > acpi_scan_lock. The organization I was envisioning would not work > > > without deeper refactoring. > > > > Sorry to come back to this late. Has this been resolved? > > The mem_hotplug_lock lockdep splat fix in this patch has not landed. > David and I have not quite come to consensus on how to resolve online > racing removal. IIUC David wants that invalidation to be > pages_correctly_probed(), I would prefer it to be directly tied to the > object, struct memory_block, that remove_memory_block_devices() has > modified, mem->section_count = 0. I was asking about this part and I can see you have already posted a patch[1] and I do not see any reason for not merging it. [1] http://lkml.kernel.org/r/157991441887.2763922.4770790047389427325.stgit@dwillia2-desk3.amr.corp.intel.com -- Michal Hocko SUSE Labs