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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 5E7E2C433E1 for ; Mon, 17 Aug 2020 18:36:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 410F82063A for ; Mon, 17 Aug 2020 18:36:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597689381; bh=/cuD2ZRHke61dcElaO4+21/PDcRJpbABFxPbMOpsJZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TDNSiwKQUCAogMctpb3a8vxqrExY20NC81ukCTx7rauivd4X/R2b74nCTog77vB9p 3XOSG5VsUPVOCvyHnEVdnHOf5GwIKcf0cW28BnXOpiBDSwl8dv0+VZmRcC2YalX3sH AQ1nBLZ9ZrIBv8KsQ7kUSSBHBFuRZ/laRJBV3e3g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391345AbgHQSgS (ORCPT ); Mon, 17 Aug 2020 14:36:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:46686 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730966AbgHQP7Y (ORCPT ); Mon, 17 Aug 2020 11:59:24 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9ACDD207DA; Mon, 17 Aug 2020 15:59:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597679964; bh=/cuD2ZRHke61dcElaO4+21/PDcRJpbABFxPbMOpsJZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TIdxsHEZQA/x/Qdejlr9VcRrSgVfRnyJNUmOICa3oY2I1/znmnVkNx9Ou55wUUzOu mjXGiIU0Sk0pAWA4E2fzB4sDu0boQ/OEL46xNSpa3xP18QRV5d3Yc5qDUH2kmzCgdu xOdqN5AyygH7sWYae5QauW29yEW2Baj4RiG92pTw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ilya Leoshkevich , Christian Borntraeger , Gerald Schaefer , Heiko Carstens Subject: [PATCH 5.7 387/393] s390/gmap: improve THP splitting Date: Mon, 17 Aug 2020 17:17:17 +0200 Message-Id: <20200817143838.373242333@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143819.579311991@linuxfoundation.org> References: <20200817143819.579311991@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Gerald Schaefer commit ba925fa35057a062ac98c3e8138b013ce4ce351c upstream. During s390_enable_sie(), we need to take care of splitting all qemu user process THP mappings. This is currently done with follow_page(FOLL_SPLIT), by simply iterating over all vma ranges, with PAGE_SIZE increment. This logic is sub-optimal and can result in a lot of unnecessary overhead, especially when using qemu and ASAN with large shadow map. Ilya reported significant system slow-down with one CPU busy for a long time and overall unresponsiveness. Fix this by using walk_page_vma() and directly calling split_huge_pmd() only for present pmds, which greatly reduces overhead. Cc: # v5.4+ Reported-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich Acked-by: Christian Borntraeger Signed-off-by: Gerald Schaefer Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman --- arch/s390/mm/gmap.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -2485,23 +2485,36 @@ void gmap_sync_dirty_log_pmd(struct gmap } EXPORT_SYMBOL_GPL(gmap_sync_dirty_log_pmd); +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static int thp_split_walk_pmd_entry(pmd_t *pmd, unsigned long addr, + unsigned long end, struct mm_walk *walk) +{ + struct vm_area_struct *vma = walk->vma; + + split_huge_pmd(vma, pmd, addr); + return 0; +} + +static const struct mm_walk_ops thp_split_walk_ops = { + .pmd_entry = thp_split_walk_pmd_entry, +}; + static inline void thp_split_mm(struct mm_struct *mm) { -#ifdef CONFIG_TRANSPARENT_HUGEPAGE struct vm_area_struct *vma; - unsigned long addr; for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) { - for (addr = vma->vm_start; - addr < vma->vm_end; - addr += PAGE_SIZE) - follow_page(vma, addr, FOLL_SPLIT); vma->vm_flags &= ~VM_HUGEPAGE; vma->vm_flags |= VM_NOHUGEPAGE; + walk_page_vma(vma, &thp_split_walk_ops, NULL); } mm->def_flags |= VM_NOHUGEPAGE; -#endif } +#else +static inline void thp_split_mm(struct mm_struct *mm) +{ +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ /* * Remove all empty zero pages from the mapping for lazy refaulting