Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756521Ab3J1MwN (ORCPT ); Mon, 28 Oct 2013 08:52:13 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:49447 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755037Ab3J1MwM (ORCPT ); Mon, 28 Oct 2013 08:52:12 -0400 Date: Mon, 28 Oct 2013 12:48:51 +0000 From: Catalin Marinas To: Simon Baatz Cc: Russell King - ARM Linux , Ming Lei , Aaro Koskinen , Will Deacon , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-arm-kernel@lists.infradead.org" , Andrew Morton , FUJITA Tomonori , Tejun Heo , "James E.J. Bottomley" , Jens Axboe Subject: Re: ARM/kirkwood: v3.12-rc6: kernel BUG at mm/util.c:390! Message-ID: <20131028124851.GD5354@mbp> References: <20131024200730.GB17447@blackmetal.musicnaut.iki.fi> <20131026143617.GA14034@mudshark.cambridge.arm.com> <20131027195115.208f40f3@tom-ThinkPad-T410> <20131027125036.GJ17447@blackmetal.musicnaut.iki.fi> <20131027135344.GD16735@n2100.arm.linux.org.uk> <20131027141817.GA13436@schnuecks.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131027141817.GA13436@schnuecks.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2269 Lines: 62 On Sun, Oct 27, 2013 at 02:18:17PM +0000, Simon Baatz wrote: > On Sun, Oct 27, 2013 at 01:53:44PM +0000, Russell King - ARM Linux wrote: > > On Sun, Oct 27, 2013 at 09:16:53PM +0800, Ming Lei wrote: > > > On Sun, Oct 27, 2013 at 8:50 PM, Aaro Koskinen wrote: > > > > > > So... > > > > flush_kernel_dcache_page() is expected to take a struct page pointer. > > This struct page pointer is part of the kernel's array of struct pages > > which identifies every single physical page under the control of the > > kernel. > > > > Arguably, it should not crash if passed a page which has been allocated > > to the slab cache; as this is not a page cache page, > > flush_kernel_dcache_page() should merely ignore the call to it and > > simply return on these. So this makes total sense: > > In this respect, flush_kernel_dcache_page() is following > flush_dcache_page(). For example in crypto/scatterwalk.c: > > static void scatterwalk_pagedone(struct scatter_walk *walk, int out, > unsigned int more) > { > if (out) { > struct page *page; > > page = sg_page(walk->sg) + ((walk->offset - 1) >> > PAGE_SHIFT); > if (!PageSlab(page)) > flush_dcache_page(page); > } > ... > > > or in drivers/ata/libata-sff.c: > > ... > if (!do_write && !PageSlab(page)) > flush_dcache_page(page); > ... > > > (Probably, both cases should have used > flush_kernel_dcache_page() in the first place). If we say that this > check belongs in flush_kernel_dcache_page() we should also put it > into flush_dcache_page(), no? According to cachetlb.txt, flush_dcache_page() is only called on page cache pages, so this excludes the PageSlab() check. For flush_kernel_dcache_page() it says "when the kernel modifies and user page" and my reading is that this applies to either page cache or anonymous pages but not slab pages, so I would add such check to the caller. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/