Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 13 Feb 2001 04:56:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 13 Feb 2001 04:56:20 -0500 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:64516 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Tue, 13 Feb 2001 04:56:01 -0500 From: Russell King Message-Id: <200102130950.f1D9ohq01768@flint.arm.linux.org.uk> Subject: Re: [PATCH] swapin flush cache bug To: marcelo@conectiva.com.br (Marcelo Tosatti) Date: Tue, 13 Feb 2001 09:50:42 +0000 (GMT) Cc: torvalds@transmeta.com (Linus Torvalds), alan@lxorguk.ukuu.org.uk (Alan Cox), gniibe@m17n.org (NIIBE Yutaka), linux-kernel@vger.kernel.org (lkml) In-Reply-To: from "Marcelo Tosatti" at Feb 12, 2001 09:21:55 PM X-Location: london.england.earth.mulky-way.universe X-Mailer: ELM [version 2.5 PL3] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Marcelo Tosatti writes: > If lookup_swap_cache() finds a page in the swap cache, and that page was > in memory because of the swapin readahead, the cache is not flushed. > > Here is a patch to fix the problem by always flushing the cache including > for pages in the swap cache: > - > - flush_page_to_ram(page); > - flush_icache_page(vma, page); > } > > mm->rss++; > + > + flush_page_to_ram(page); > + flush_icache_page(vma, page); Surely if the page is in the swap cache, we don't need the flush_page_to_ram() because the data is already written to the page. Yes, there may be some reminents of it in the cache due to it being written to disk via PIO. Thinking about it some more - we have a process. It used to contain page P at address V. We unmapped the page (and did the right thing with the caches). Now, something wants to access address V, so we pull the page from the swap cache, and place page P back at address V. We therefore shouldn't need any cache manipulation at this point. What was the problem? The old code seems to behave well on a virtual address indexed virtual address tagged cache. -- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html - 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/