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 0DAFBCCA488 for ; Mon, 13 Jun 2022 14:51:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1385908AbiFMOuU (ORCPT ); Mon, 13 Jun 2022 10:50:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1386508AbiFMOpX (ORCPT ); Mon, 13 Jun 2022 10:45:23 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4D02BC6ED; Mon, 13 Jun 2022 04:52:11 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3B7C8B80EA7; Mon, 13 Jun 2022 11:52:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A22BEC34114; Mon, 13 Jun 2022 11:52:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655121127; bh=1UixyvoLN2QSYpYfK0BK4OCi/4U+aVgFQL0tX8f+yag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q6vBvU5Va20qriFZCJ+0o8/AwIvJ27V544IFFFdfZ0qrtZ3cjRyU4EzSn55+zqtKB mMpfJsGX9IEjuKL++FRskNAhAd04YVWWmZsvGVWPxKnx5vYST4IWntaFp9yKWe21x0 OJY+LR/5HWGiGEJMAju7dWI+RoN7bbg8qYHTSxr0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+9e27a75a8c24f3fe75c1@syzkaller.appspotmail.com, "Matthew Wilcox (Oracle)" Subject: [PATCH 5.17 282/298] mm/huge_memory: Fix xarray node memory leak Date: Mon, 13 Jun 2022 12:12:56 +0200 Message-Id: <20220613094933.634623237@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094924.913340374@linuxfoundation.org> References: <20220613094924.913340374@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthew Wilcox (Oracle) commit 69a37a8ba1b408a1c7616494aa7018e4b3844cbe upstream. If xas_split_alloc() fails to allocate the necessary nodes to complete the xarray entry split, it sets the xa_state to -ENOMEM, which xas_nomem() then interprets as "Please allocate more memory", not as "Please free any unnecessary memory" (which was the intended outcome). It's confusing to use xas_nomem() to free memory in this context, so call xas_destroy() instead. Reported-by: syzbot+9e27a75a8c24f3fe75c1@syzkaller.appspotmail.com Fixes: 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache") Cc: stable@vger.kernel.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Greg Kroah-Hartman --- include/linux/xarray.h | 1 + lib/xarray.c | 5 +++-- mm/huge_memory.c | 3 +-- 3 files changed, 5 insertions(+), 4 deletions(-) --- a/include/linux/xarray.h +++ b/include/linux/xarray.h @@ -1506,6 +1506,7 @@ void *xas_find_marked(struct xa_state *, void xas_init_marks(const struct xa_state *); bool xas_nomem(struct xa_state *, gfp_t); +void xas_destroy(struct xa_state *); void xas_pause(struct xa_state *); void xas_create_range(struct xa_state *); --- a/lib/xarray.c +++ b/lib/xarray.c @@ -264,9 +264,10 @@ static void xa_node_free(struct xa_node * xas_destroy() - Free any resources allocated during the XArray operation. * @xas: XArray operation state. * - * This function is now internal-only. + * Most users will not need to call this function; it is called for you + * by xas_nomem(). */ -static void xas_destroy(struct xa_state *xas) +void xas_destroy(struct xa_state *xas) { struct xa_node *next, *node = xas->xa_alloc; --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2736,8 +2736,7 @@ out_unlock: if (mapping) i_mmap_unlock_read(mapping); out: - /* Free any memory we didn't use */ - xas_nomem(&xas, 0); + xas_destroy(&xas); count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); return ret; }