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[62.201.165.239]) by smtp.gmail.com with ESMTPSA id a1-v6sm8859580wrt.79.2018.10.15.08.30.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Oct 2018 08:30:54 -0700 (PDT) Received: from d104.suse.de (charybdis-ext.suse.de [195.135.221.2]) by techadventures.net (Postfix) with ESMTPA id 4B1191259A8; Mon, 15 Oct 2018 17:30:52 +0200 (CEST) From: Oscar Salvador To: akpm@linux-foundation.org Cc: mhocko@suse.com, dan.j.williams@intel.com, yasu.isimatu@gmail.com, rppt@linux.vnet.ibm.com, malat@debian.org, linux-kernel@vger.kernel.org, pavel.tatashin@microsoft.com, jglisse@redhat.com, Jonathan.Cameron@huawei.com, rafael@kernel.org, david@redhat.com, dave.jiang@intel.com, linux-mm@kvack.org, alexander.h.duyck@linux.intel.com, Oscar Salvador Subject: [PATCH 3/5] mm/memory_hotplug: Check for IORESOURCE_SYSRAM in release_mem_region_adjustable Date: Mon, 15 Oct 2018 17:30:32 +0200 Message-Id: <20181015153034.32203-4-osalvador@techadventures.net> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20181015153034.32203-1-osalvador@techadventures.net> References: <20181015153034.32203-1-osalvador@techadventures.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oscar Salvador This is a preparation for the next patch. Currently, we only call release_mem_region_adjustable() in __remove_pages if the zone is not ZONE_DEVICE, because resources that belong to HMM/devm are being released by themselves with devm_release_mem_region. Since we do not want to touch any zone/page stuff during the removing of the memory (but during the offlining), we do not want to check for the zone here. So we need another way to tell release_mem_region_adjustable() to not realease the resource in case it belongs to HMM/devm. HMM/devm acquires/releases a resource through devm_request_mem_region/devm_release_mem_region. These resources have the flag IORESOURCE_MEM, while resources acquired by hot-add memory path (register_memory_resource()) contain IORESOURCE_SYSTEM_RAM. So, we can check for this flag in release_mem_region_adjustable, and if the resource does not contain such flag, we know that we are dealing with a HMM/devm resource, so we can back off. Signed-off-by: Oscar Salvador --- kernel/resource.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kernel/resource.c b/kernel/resource.c index 81937830a42f..c45decd7d6af 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -1272,6 +1272,22 @@ int release_mem_region_adjustable(struct resource *parent, continue; } + /* + * All memory regions added from memory-hotplug path + * have the flag IORESOURCE_SYSTEM_RAM. + * If the resource does not have this flag, we know that + * we are dealing with a resource coming from HMM/devm. + * HMM/devm use another mechanism to add/release a resource. + * This goes via devm_request_mem_region and + * devm_release_mem_region. + * HMM/devm take care to release their resources when they want, + * so if we are dealing with them, let us just back off here. + */ + if (!(res->flags & IORESOURCE_SYSRAM)) { + ret = 0; + break; + } + if (!(res->flags & IORESOURCE_MEM)) break; -- 2.13.6