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[209.85.220.65]) by mx.google.com with SMTPS id m8sor25684074otm.167.2019.07.25.02.22.58 for (Google Transport Security); Thu, 25 Jul 2019 02:22:58 -0700 (PDT) Received-SPF: pass (google.com: domain of rjwysocki@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; spf=pass (google.com: domain of rjwysocki@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=rjwysocki@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Google-Smtp-Source: APXvYqxJ49+1aZ6N4TDMyBMfQsD/Uphq9/3dCsGS122VqG+v2Ww7f6i5dT2dazWN0C3ylFEI+mrm0iTK0F636Zu0+Q8= X-Received: by 2002:a05:6830:1516:: with SMTP id k22mr59724305otp.189.1564046578263; Thu, 25 Jul 2019 02:22:58 -0700 (PDT) MIME-Version: 1.0 References: <20190724143017.12841-1-david@redhat.com> <20190725091625.GA15848@linux> In-Reply-To: <20190725091625.GA15848@linux> From: "Rafael J. Wysocki" Date: Thu, 25 Jul 2019 11:22:46 +0200 Message-ID: Subject: Re: [PATCH v1] ACPI / scan: Acquire device_hotplug_lock in acpi_scan_init() To: Oscar Salvador Cc: David Hildenbrand , Linux Kernel Mailing List , Linux Memory Management List , ACPI Devel Maling List , "Rafael J. Wysocki" , Andrew Morton , Michal Hocko Content-Type: text/plain; charset="UTF-8" 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 Thu, Jul 25, 2019 at 11:18 AM Oscar Salvador wrote: > > On Wed, Jul 24, 2019 at 04:30:17PM +0200, David Hildenbrand wrote: > > We end up calling __add_memory() without the device hotplug lock held. > > (I used a local patch to assert in __add_memory() that the > > device_hotplug_lock is held - I might upstream that as well soon) > > > > [ 26.771684] create_memory_block_devices+0xa4/0x140 > > [ 26.772952] add_memory_resource+0xde/0x200 > > [ 26.773987] __add_memory+0x6e/0xa0 > > [ 26.775161] acpi_memory_device_add+0x149/0x2b0 > > [ 26.776263] acpi_bus_attach+0xf1/0x1f0 > > [ 26.777247] acpi_bus_attach+0x66/0x1f0 > > [ 26.778268] acpi_bus_attach+0x66/0x1f0 > > [ 26.779073] acpi_bus_attach+0x66/0x1f0 > > [ 26.780143] acpi_bus_scan+0x3e/0x90 > > [ 26.780844] acpi_scan_init+0x109/0x257 > > [ 26.781638] acpi_init+0x2ab/0x30d > > [ 26.782248] do_one_initcall+0x58/0x2cf > > [ 26.783181] kernel_init_freeable+0x1bd/0x247 > > [ 26.784345] kernel_init+0x5/0xf1 > > [ 26.785314] ret_from_fork+0x3a/0x50 > > > > So perform the locking just like in acpi_device_hotplug(). > > > > Cc: "Rafael J. Wysocki" > > Cc: Len Brown > Cc: Andrew Morton > > Cc: Oscar Salvador > > Cc: Michal Hocko > > Signed-off-by: David Hildenbrand > > Given that that call comes from a __init function, so while booting, I wonder > how bad it is. Yes, it probably does not matter. > Anyway, let us be consistent: Right.