From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id B84466B0032 for ; Thu, 22 Jan 2015 19:20:24 -0500 (EST) Received: by mail-pd0-f173.google.com with SMTP id fp1so4849616pdb.4 for ; Thu, 22 Jan 2015 16:20:24 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id yb6si13817329pbc.219.2015.01.22.16.20.22 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Jan 2015 16:20:23 -0800 (PST) Date: Thu, 22 Jan 2015 16:20:21 -0800 From: Andrew Morton Subject: Re: [PATCHv2] mm: Don't offset memmap for flatmem Message-Id: <20150122162021.aa861aeb53c22206a19ebbcb@linux-foundation.org> In-Reply-To: <1421888500-24364-1-git-send-email-lauraa@codeaurora.org> References: <1421804273-29947-1-git-send-email-lauraa@codeaurora.org> <1421888500-24364-1-git-send-email-lauraa@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Laura Abbott Cc: Vlastimil Babka , Srinivas Kandagatla , linux-arm-kernel@lists.infradead.org, Russell King - ARM Linux , ssantosh@kernel.org, Kevin Hilman , Arnd Bergman , Stephen Boyd , linux-mm@kvack.org, Kumar Gala On Wed, 21 Jan 2015 17:01:40 -0800 Laura Abbott wrote: > Srinivas Kandagatla reported bad page messages when trying to > remove the bottom 2MB on an ARM based IFC6410 board > > BUG: Bad page state in process swapper pfn:fffa8 > page:ef7fb500 count:0 mapcount:0 mapping: (null) index:0x0 > flags: 0x96640253(locked|error|dirty|active|arch_1|reclaim|mlocked) > page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set > bad because of flags: > flags: 0x200041(locked|active|mlocked) > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 3.19.0-rc3-00007-g412f9ba-dirty #816 > Hardware name: Qualcomm (Flattened Device Tree) > [] (unwind_backtrace) from [] (show_stack+0x20/0x24) > [] (show_stack) from [] (dump_stack+0x80/0x9c) > [] (dump_stack) from [] (bad_page+0xc8/0x128) > [] (bad_page) from [] (free_pages_prepare+0x168/0x1e0) > [] (free_pages_prepare) from [] (free_hot_cold_page+0x3c/0x174) > [] (free_hot_cold_page) from [] (__free_pages+0x54/0x58) > [] (__free_pages) from [] (free_highmem_page+0x38/0x88) > [] (free_highmem_page) from [] (mem_init+0x240/0x430) > [] (mem_init) from [] (start_kernel+0x1e4/0x3c8) > [] (start_kernel) from [<80208074>] (0x80208074) > Disabling lock debugging due to kernel taint > > Removing the lower 2MB made the start of the lowmem zone to no longer > be page block aligned. IFC6410 uses CONFIG_FLATMEM where > alloc_node_mem_map allocates memory for the mem_map. alloc_node_mem_map > will offset for unaligned nodes with the assumption the pfn/page > translation functions will account for the offset. The functions for > CONFIG_FLATMEM do not offset however, resulting in overrunning > the memmap array. Just use the allocated memmap without any offset > when running with CONFIG_FLATMEM to avoid the overrun. > I don't think v2 addressed Vlastimil's review comment? -- 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