Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751208AbWCCF0n (ORCPT ); Fri, 3 Mar 2006 00:26:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750858AbWCCF0n (ORCPT ); Fri, 3 Mar 2006 00:26:43 -0500 Received: from ozlabs.org ([203.10.76.45]:55985 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S1751274AbWCCF0m (ORCPT ); Fri, 3 Mar 2006 00:26:42 -0500 Date: Fri, 3 Mar 2006 16:26:02 +1100 From: "'David Gibson'" To: Hugh Dickins Cc: Andrew Morton , "Chen, Kenneth W" , William Irwin , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: hugepage: Fix hugepage logic in free_pgtables() harder Message-ID: <20060303052602.GL23766@localhost.localdomain> Mail-Followup-To: 'David Gibson' , Hugh Dickins , Andrew Morton , "Chen, Kenneth W" , William Irwin , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org References: <20060303010408.GG23766@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1712 Lines: 35 On Fri, Mar 03, 2006 at 05:18:51AM +0000, Hugh Dickins wrote: > On Fri, 3 Mar 2006, 'David Gibson' wrote: > > > Sigh. Turns out the hugepage logic in free_pgtables() was doubly > > broken. The loop coalescing multiple normal page VMAs into one call > > to free_pgd_range() had an off by one error, which could mean it would > > coalesce one hugepage VMA into the same bundle (checking 'vma' not > > 'next' in the loop). I transferred this bug into the new > > is_vm_hugetlb_page() based version. Here's the fix. > > > > This one didn't bite on powerpc previously for the same reason the > > is_hugepage_only_range() problem didn't: powerpc's > > hugetlb_free_pgd_range() is identical to free_pgd_range(). It didn't > > bite on ia64 because the hugepage region is distant enough from any > > other region that the separated PMD_SIZE distance test would always > > prevent coalescing the two together. > > I agree with your patch, but not with your comment: it's just a fix > to your earlier patch, there's no such off-by-one in the mainline > free_pgtables. Probably you were misled by my use of "vma->vm_mm" > rather than "next->vm_mm", equal but admittedly confusing, when > looking at the "next" vma. Ah, yes, indeed. The bug's all my fault, but it's still a bug. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson - 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/