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[209.132.183.28]) by mx.google.com with ESMTPS id l1si2259738qkc.47.2019.04.05.06.53.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 05 Apr 2019 06:53:27 -0700 (PDT) Received-SPF: pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jglisse@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=jglisse@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2F5484902D; Fri, 5 Apr 2019 13:53:27 +0000 (UTC) Received: from redhat.com (unknown [10.20.6.236]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E13860C11; Fri, 5 Apr 2019 13:53:26 +0000 (UTC) Date: Fri, 5 Apr 2019 09:53:24 -0400 From: Jerome Glisse To: Anshuman Khandual Cc: "linux-mm@kvack.org" , Linux ARM , Dan Williams , Will Deacon , Catalin Marinas Subject: Re: struct dev_pagemap corruption Message-ID: <20190405135324.GA5627@redhat.com> References: <7885dce0-edbe-db04-b5ec-bd271c9a0612@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7885dce0-edbe-db04-b5ec-bd271c9a0612@arm.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 05 Apr 2019 13:53:27 +0000 (UTC) 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, Apr 05, 2019 at 10:10:22AM +0530, Anshuman Khandual wrote: > Hello, > > On arm64 platform "struct dev_pagemap" is getting corrupted during ZONE_DEVICE > unmapping path through device_destroy(). Its device memory range end address > (pgmap->res.end) which is getting corrupted in this particular case. AFAICS > pgmap which gets initialized by the driver and mapped with devm_memremap_pages() > should retain it's values during the unmapping path as well. Is this assumption > right ? > > [ 62.779412] Call trace: > [ 62.779808] dump_backtrace+0x0/0x118 > [ 62.780460] show_stack+0x14/0x20 > [ 62.781204] dump_stack+0xa8/0xcc > [ 62.781941] devm_memremap_pages_release+0x24/0x1d8 > [ 62.783021] devm_action_release+0x10/0x18 > [ 62.783911] release_nodes+0x1b0/0x220 > [ 62.784732] devres_release_all+0x34/0x50 > [ 62.785623] device_release+0x24/0x90 > [ 62.786454] kobject_put+0x74/0xe8 > [ 62.787214] device_destroy+0x48/0x58 > [ 62.788041] zone_device_public_altmap_init+0x404/0x42c [zone_device_public_altmap] > [ 62.789675] do_one_initcall+0x74/0x190 > [ 62.790528] do_init_module+0x50/0x1c0 > [ 62.791346] load_module+0x1be4/0x2140 > [ 62.792192] __se_sys_finit_module+0xb8/0xc8 > [ 62.793128] __arm64_sys_finit_module+0x18/0x20 > [ 62.794128] el0_svc_handler+0x88/0x100 > [ 62.794989] el0_svc+0x8/0xc > > The problem can be traced down here. > > diff --git a/drivers/base/devres.c b/drivers/base/devres.c > index e038e2b3b7ea..2a410c88c596 100644 > --- a/drivers/base/devres.c > +++ b/drivers/base/devres.c > @@ -33,7 +33,7 @@ struct devres { > * Thus we use ARCH_KMALLOC_MINALIGN here and get exactly the same > * buffer alignment as if it was allocated by plain kmalloc(). > */ > - u8 __aligned(ARCH_KMALLOC_MINALIGN) data[]; > + u8 __aligned(__alignof__(unsigned long long)) data[]; > }; I doubt that pgmap->res.end get corrupted during device_destroy() but given that the above changes fix the issue it kind of boggle the mind. If i where to debug this i would probably run a kernel with qemu -s to get a gdbserver and then attach gdb and set breakpoint on devm_memremap_pages() then when that trigger i would set memory watch on the pgmap->res.end (there use to be way to use memory as pmem through kernel boot option). A printk alternative solution is, assuming you only have one pgmap, add a global static struct pgmap *debug_pgmap = NULL; in memremap.c set that in devm_memremap_pages() and add an helper function: void debug_pgmap(const char *file, unsigned line) { printk(... file, line); printk(... debug_pmap->res.end); } In a header: #define DEBUG_PGMAP debug_pgmap(__FILE__, __LINE__); Then sprinkle DEBUG_PGMAP within device_destroy(), device_unregister(), device_release() and see when it get corrupted. gdb would be faster but sometime i got issue with memory watchpoint and virt. Cheers, Jérôme