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=-6.8 required=3.0 tests=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=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 115E4C33C9B for ; Tue, 7 Jan 2020 21:23:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8F4B2080A for ; Tue, 7 Jan 2020 21:23:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578432201; bh=AK1AVXO5ClegKvysWc2GyWGCDLaaS1BUynmfwuiEd7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LAbYTP5MIUws34trI7JW+YcrLa0qSQpL0KhzdWvaN3M7A1JaLCdXLdN83j85ADsjx gD2+JmTJ6gtv3nIRQ2Qr/LWPH2vYN/UztT58z4oxa8k8nP/dsevyEuxfE4iHoh38ok XY7Y+HEy6L0O8M4TAHdmAewm75FtWq++bblklNII= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727089AbgAGVXV (ORCPT ); Tue, 7 Jan 2020 16:23:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:38692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728568AbgAGVB1 (ORCPT ); Tue, 7 Jan 2020 16:01:27 -0500 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 6E2202087F; Tue, 7 Jan 2020 21:01:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578430886; bh=AK1AVXO5ClegKvysWc2GyWGCDLaaS1BUynmfwuiEd7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pePvFFxhWMhYHSHq6c85p29Mo2rMITnokw9KLIF0BgSYGXlKeotwpM5viHHsTBA4i pGPDwUlUixiPtobvLBnoQBciRpzSFRBiBIrRH14AyE/JF8bO20hJRDWO4hq7K6ERjg LrmItUUygOSuATUVxIegnULZPRV269PMlyAPIIOI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alastair DSilva , Michael Ellerman Subject: [PATCH 5.4 138/191] powerpc: Chunk calls to flush_dcache_range in arch_*_memory Date: Tue, 7 Jan 2020 21:54:18 +0100 Message-Id: <20200107205340.358424692@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107205332.984228665@linuxfoundation.org> References: <20200107205332.984228665@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Alastair D'Silva commit 076265907cf9633bbef861c7c2a1c26a8209f283 upstream. When presented with large amounts of memory being hotplugged (in my test case, ~890GB), the call to flush_dcache_range takes a while (~50 seconds), triggering RCU stalls. This patch breaks up the call into 1GB chunks, calling cond_resched() inbetween to allow the scheduler to run. Fixes: fb5924fddf9e ("powerpc/mm: Flush cache on memory hot(un)plug") Signed-off-by: Alastair D'Silva Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191104023305.9581-6-alastair@au1.ibm.com Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/mm/mem.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -104,6 +104,27 @@ int __weak remove_section_mapping(unsign return -ENODEV; } +#define FLUSH_CHUNK_SIZE SZ_1G +/** + * flush_dcache_range_chunked(): Write any modified data cache blocks out to + * memory and invalidate them, in chunks of up to FLUSH_CHUNK_SIZE + * Does not invalidate the corresponding instruction cache blocks. + * + * @start: the start address + * @stop: the stop address (exclusive) + * @chunk: the max size of the chunks + */ +static void flush_dcache_range_chunked(unsigned long start, unsigned long stop, + unsigned long chunk) +{ + unsigned long i; + + for (i = start; i < stop; i += chunk) { + flush_dcache_range(i, min(stop, start + chunk)); + cond_resched(); + } +} + int __ref arch_add_memory(int nid, u64 start, u64 size, struct mhp_restrictions *restrictions) { @@ -120,7 +141,8 @@ int __ref arch_add_memory(int nid, u64 s start, start + size, rc); return -EFAULT; } - flush_dcache_range(start, start + size); + + flush_dcache_range_chunked(start, start + size, FLUSH_CHUNK_SIZE); return __add_pages(nid, start_pfn, nr_pages, restrictions); } @@ -136,7 +158,8 @@ void __ref arch_remove_memory(int nid, u /* Remove htab bolted mappings for this section of memory */ start = (unsigned long)__va(start); - flush_dcache_range(start, start + size); + flush_dcache_range_chunked(start, start + size, FLUSH_CHUNK_SIZE); + ret = remove_section_mapping(start, start + size); WARN_ON_ONCE(ret);