From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by kanga.kvack.org (Postfix) with ESMTP id 26F956B0037 for ; Mon, 28 Oct 2013 08:49:41 -0400 (EDT) Received: by mail-pa0-f49.google.com with SMTP id lj1so7119222pab.22 for ; Mon, 28 Oct 2013 05:49:40 -0700 (PDT) Received: from psmtp.com ([74.125.245.178]) by mx.google.com with SMTP id ar5si11923763pbd.302.2013.10.28.05.49.38 for ; Mon, 28 Oct 2013 05:49:39 -0700 (PDT) Date: Mon, 28 Oct 2013 12:48:51 +0000 From: Catalin Marinas 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org