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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5A07E784AE for ; Mon, 2 Oct 2023 07:09:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235656AbjJBHJ2 (ORCPT ); Mon, 2 Oct 2023 03:09:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235599AbjJBHJ0 (ORCPT ); Mon, 2 Oct 2023 03:09:26 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C5218E; Mon, 2 Oct 2023 00:09:24 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id BD2C121853; Mon, 2 Oct 2023 07:09:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1696230562; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8vcbNq67Xl3f2iKsCH4we0sJgW4X2ca2S7bOAsiex1Q=; b=sYBuE9DmG1frwKtVsSRTG3Ale2r5OTm85xqfZD4SMQgyARAWCQuqkgePAMH2qt5USeFSzU +3vTGLz702iOSggMMRZMufC+M6m+JAsB/esv//AAAKxAUUcVtuITmwd1siIpONwABSppuA O+ZYuCQ4dJgnDNq4hb0wZ7Qj8p6sC3Q= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1696230562; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8vcbNq67Xl3f2iKsCH4we0sJgW4X2ca2S7bOAsiex1Q=; b=Je9vocE06l6uaNRhWqNdvU+Sf0X8KCDs3p9+1pNsnpesOSRzY1tacE+DfjZuDBsZ5JmuP6 Mk1KJum7qrwXhKCg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 92F6613456; Mon, 2 Oct 2023 07:09:22 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xE9RI6JsGmWqeAAAMHmgww (envelope-from ); Mon, 02 Oct 2023 07:09:22 +0000 Message-ID: <8055dadf-a8ee-6706-79b3-6fc61d77c71e@suse.cz> Date: Mon, 2 Oct 2023 09:09:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v3 1/3] mmap: Fix vma_iterator in error path of vma_merge() Content-Language: en-US To: "Liam R. Howlett" , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jann Horn , Lorenzo Stoakes , Suren Baghdasaryan , Matthew Wilcox , stable@vger.kernel.org References: <20230929183041.2835469-1-Liam.Howlett@oracle.com> <20230929183041.2835469-2-Liam.Howlett@oracle.com> From: Vlastimil Babka In-Reply-To: <20230929183041.2835469-2-Liam.Howlett@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/29/23 20:30, Liam R. Howlett wrote: > During the error path, the vma iterator may not be correctly positioned > or set to the correct range. Undo the vma_prev() call by resetting to > the passed in address. Re-walking to the same range will fix the range > to the area previously passed in. > > Users would notice increased cycles as vma_merge() would be called an > extra time with vma == prev, and thus would fail to merge and return. > > Link: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/ > Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/ > Fixes: 18b098af2890 ("vma_merge: set vma iterator to correct position.") > Cc: stable@vger.kernel.org > Cc: Jann Horn > Signed-off-by: Liam R. Howlett Acked-by: Vlastimil Babka > --- > mm/mmap.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index b56a7f0c9f85..acb7dea49e23 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -975,7 +975,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > > /* Error in anon_vma clone. */ > if (err) > - return NULL; > + goto anon_vma_fail; > > if (vma_start < vma->vm_start || vma_end > vma->vm_end) > vma_expanded = true; > @@ -988,7 +988,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > } > > if (vma_iter_prealloc(vmi, vma)) > - return NULL; > + goto prealloc_fail; > > init_multi_vma_prep(&vp, vma, adjust, remove, remove2); > VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && > @@ -1016,6 +1016,12 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, > vma_complete(&vp, vmi, mm); > khugepaged_enter_vma(res, vm_flags); > return res; > + > +prealloc_fail: > +anon_vma_fail: > + vma_iter_set(vmi, addr); > + vma_iter_load(vmi); > + return NULL; > } > > /*