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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 A540CC433B4 for ; Sat, 15 May 2021 00:27:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82BB261176 for ; Sat, 15 May 2021 00:27:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230185AbhEOA2e (ORCPT ); Fri, 14 May 2021 20:28:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:43780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230022AbhEOA2e (ORCPT ); Fri, 14 May 2021 20:28:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6491561444; Sat, 15 May 2021 00:27:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1621038442; bh=3/9Ox0agGVL/dQY6tNQC0j5SrRwoKhe5WPL15rf3sCs=; h=Date:From:To:Subject:In-Reply-To:From; b=pdX+dsQT8We1s7iNMIqjQAf5OKj8uG/ruuhqZxGI27LJG2uNNt8IZOuO106MIcG8P 4fMvmBUpuzFmbHza9OylSXcReF53dKATL60vpafK2IxkNgAV/9FccT1D47LnbOI87s RUPD0PrAUvA5cLMa2/uvqS4gFfcsm0/r/6UkELTk= Date: Fri, 14 May 2021 17:27:22 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hughd@google.com, linmiaohe@huawei.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 07/13] ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()" Message-ID: <20210515002722.gaOMpxsKF%akpm@linux-foundation.org> In-Reply-To: <20210514172634.9018621171d5334ceee97e95@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Hugh Dickins Subject: ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()" This reverts commit 3e96b6a2e9ad929a3230a22f4d64a74671a0720b. General Protection Fault in rmap_walk_ksm() under memory pressure: remove_rmap_item_from_tree() needs to take page lock, of course. Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2105092253500.1127@eggly.anvils Signed-off-by: Hugh Dickins Cc: Miaohe Lin Signed-off-by: Andrew Morton --- mm/ksm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/ksm.c~ksm-revert-use-get_ksm_page_nolock-to-get-ksm-page-in-remove_rmap_item_from_tree +++ a/mm/ksm.c @@ -776,11 +776,12 @@ static void remove_rmap_item_from_tree(s struct page *page; stable_node = rmap_item->head; - page = get_ksm_page(stable_node, GET_KSM_PAGE_NOLOCK); + page = get_ksm_page(stable_node, GET_KSM_PAGE_LOCK); if (!page) goto out; hlist_del(&rmap_item->hlist); + unlock_page(page); put_page(page); if (!hlist_empty(&stable_node->hlist)) _