From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF2FBC433E3 for ; Fri, 10 Jul 2020 19:44:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A756620748 for ; Fri, 10 Jul 2020 19:44:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PM3B9HXG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728494AbgGJToQ (ORCPT ); Fri, 10 Jul 2020 15:44:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726908AbgGJToP (ORCPT ); Fri, 10 Jul 2020 15:44:15 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36B1FC08C5DD for ; Fri, 10 Jul 2020 12:44:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=1VmzFcnP3/YHRUmS2rHUD2i9AUE3TqsbsQgcN7fI++c=; b=PM3B9HXGyD27uvwZ30Ek7dMPFA 5CV7hg4LgGNw2eihia5l3D8My2/QsOar16IfP9pas9NO/wYLRWnys5QalMMuTo7/K4OPQihIL5sVH 7bs7BglerBuOv/xMGOrMYZhRWJxz26+77TZe/Xc8ogjTY8ZP3SRdOLSJWsYEjLAMoSWO/v5ck7WTR C5V13cE7dd29OF94UPrcuZ4DF22bNSGklyxw3SeI6IrfkSVtctby668q8sQPRDNbkBTu4H15kZN7Z D4dU6awKKOryTe1y8k4QsiSsh5D2jquztQzJQo59RQe3vgB+QLHXWWyiwc9UlO5le6HFtepFiMkDt 7ZZlG2xg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jtywI-0003Qt-5f; Fri, 10 Jul 2020 19:44:06 +0000 Date: Fri, 10 Jul 2020 20:44:06 +0100 From: Matthew Wilcox To: "Uladzislau Rezki (Sony)" Cc: Andrew Morton , linux-mm@kvack.org, LKML , Hillf Danton , Michal Hocko , Oleksiy Avramchenko , Steven Rostedt Subject: Re: [PATCH 1/1] mm/vmalloc.c: Add an error message if two areas overlap Message-ID: <20200710194406.GP12769@casper.infradead.org> References: <20200710194042.2510-1-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200710194042.2510-1-urezki@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 10, 2020 at 09:40:42PM +0200, Uladzislau Rezki (Sony) wrote: > Before triggering a BUG() it would be useful to understand > how two areas overlap between each other. Print information > about start/end addresses of both VAs and their addresses. > > For example if both are identical it could mean double free. > > Signed-off-by: Uladzislau Rezki (Sony) > --- > mm/vmalloc.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 5a2b55c8dd9a..1679b01febcd 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -549,8 +549,13 @@ find_va_links(struct vmap_area *va, > else if (va->va_end > tmp_va->va_start && > va->va_start >= tmp_va->va_end) > link = &(*link)->rb_right; > - else > + else { > + pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n", > + va, va->va_start, va->va_end, tmp_va, > + tmp_va->va_start, tmp_va->va_end); It might be helpful to have a "vmalloc:" prefix to that string to indicate where to start searching. And I don't think we're supposed to use %px without a really good justification these days. Can we do without the BUG()? Maybe just break out and decline to insert the conflicting range? > BUG(); > + } > } while (*link); > > *parent = &tmp_va->rb_node; > @@ -1993,6 +1998,9 @@ static void vmap_init_free_space(void) > insert_vmap_area_augment(free, NULL, > &free_vmap_area_root, > &free_vmap_area_list); > + insert_vmap_area_augment(free, NULL, > + &free_vmap_area_root, > + &free_vmap_area_list); This is surely testing code that you forgot to delete?