From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx178.postini.com [74.125.245.178]) by kanga.kvack.org (Postfix) with SMTP id D45226B0039 for ; Thu, 9 May 2013 10:40:48 -0400 (EDT) Message-ID: <518BB4F2.2040704@redhat.com> Date: Thu, 09 May 2013 10:38:42 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] COMPACTION: bugfix of improper cache flush in MIGRATION code. References: <20130509001821.15951.98705.stgit@linux-yegoshin> In-Reply-To: <20130509001821.15951.98705.stgit@linux-yegoshin> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Leonid Yegoshin Cc: mhocko@suse.cz, akpm@linux-foundation.org, mgorman@suse.de, kamezawa.hiroyu@jp.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On 05/08/2013 08:18 PM, Leonid Yegoshin wrote: > Page 'new' during MIGRATION can't be flushed by flush_cache_page(). > Using flush_cache_page(vma, addr, pfn) is justified only if > page is already placed in process page table, and that is done right > after flush_cache_page(). But without it the arch function has > no knowledge of process PTE and does nothing. > > Besides that, flush_cache_page() flushes an application cache, > kernel has a different page virtual address and dirtied it. > > Replace it with flush_dcache_page(new) which is a proper usage. > > Old page is flushed in try_to_unmap_one() before MIGRATION. > > This bug takes place in Sead3 board with M14Kc MIPS CPU without > cache aliasing (but Harvard arch - separate I and D cache) > in tight memory environment (128MB) each 1-3days on SOAK test. > It fails in cc1 during kernel build (SIGILL, SIGBUS, SIGSEG) if > CONFIG_COMPACTION is switched ON. Good catch! > Author: Leonid Yegoshin > Signed-off-by: Leonid Yegoshin Acked-by: Rik van Riel -- 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