From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id E05846B01E3 for ; Thu, 13 May 2010 22:28:54 -0400 (EDT) Message-ID: <4BECB562.2080200@cesarb.net> Date: Thu, 13 May 2010 23:28:50 -0300 From: Cesar Eduardo Barros MIME-Version: 1.0 Subject: Re: [PATCH] radix-tree: fix radix_tree_prev_hole underflow case References: <1273802724-3414-1-git-send-email-cesarb@cesarb.net> <20100514021508.GA7810@localhost> In-Reply-To: <20100514021508.GA7810@localhost> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Andrew Morton List-ID: Em 13-05-2010 23:15, Wu Fengguang escreveu: > On Fri, May 14, 2010 at 10:05:24AM +0800, Cesar Eduardo Barros wrote: >> radix_tree_prev_hole() used LONG_MAX to detect underflow; however, >> ULONG_MAX is clearly what was intended, both here and by its only user >> (count_history_pages at mm/readahead.c). > > Good catch, thanks! I actually have a more smart > radix_tree_prev_hole() that uses ULONG_MAX. I saw it already ([PATCH 14/16] radixtree: speed up the search for hole), but it misses the LONG_MAX in the documentation comment. > Andrew, fortunately this bug has little impact on readahead. I agree, if I read it correctly it should only have any impact either when very near LONG_MAX or in the unlikely case that there is no hole at ULONG_MAX. And even then, the impact should be limited. -- Cesar Eduardo Barros cesarb@cesarb.net cesar.barros@gmail.com -- 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