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[195.135.220.15]) by mx.google.com with ESMTPS id u8si10586868edm.69.2019.07.25.02.18.57 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Jul 2019 02:18:57 -0700 (PDT) Received-SPF: pass (google.com: domain of osalvador@suse.de designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of osalvador@suse.de designates 195.135.220.15 as permitted sender) smtp.mailfrom=osalvador@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id D7FBBADC4; Thu, 25 Jul 2019 09:18:56 +0000 (UTC) Date: Thu, 25 Jul 2019 11:18:54 +0200 From: Oscar Salvador To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-acpi@vger.kernel.org, "Rafael J. Wysocki" , Andrew Morton , Michal Hocko Subject: Re: [PATCH v1] ACPI / scan: Acquire device_hotplug_lock in acpi_scan_init() Message-ID: <20190725091625.GA15848@linux> References: <20190724143017.12841-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190724143017.12841-1-david@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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, 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. Anyway, let us be consistent: Reviewed-by: Oscar Salvador > --- > drivers/acpi/scan.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index 0e28270b0fd8..cbc9d64b48dd 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -2204,7 +2204,9 @@ int __init acpi_scan_init(void) > acpi_gpe_apply_masked_gpes(); > acpi_update_all_gpes(); > > + lock_device_hotplug(); > mutex_lock(&acpi_scan_lock); > + > /* > * Enumerate devices in the ACPI namespace. > */ > @@ -2232,6 +2234,7 @@ int __init acpi_scan_init(void) > > out: > mutex_unlock(&acpi_scan_lock); > + unlock_device_hotplug(); > return result; > } > > -- > 2.21.0 > -- Oscar Salvador SUSE L3