From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:37368 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932403AbeD3T27 (ORCPT ); Mon, 30 Apr 2018 15:28:59 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Balbir Singh , Reza Arbab , Rashmica Gupta , Michael Ellerman Subject: [PATCH 4.16 080/113] powerpc/mm: Flush cache on memory hot(un)plug Date: Mon, 30 Apr 2018 12:24:51 -0700 Message-Id: <20180430184018.566463069@linuxfoundation.org> In-Reply-To: <20180430184015.043892819@linuxfoundation.org> References: <20180430184015.043892819@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Balbir Singh commit fb5924fddf9ee31db04da7ad4e8c3434a387101b upstream. This patch adds support for flushing potentially dirty cache lines when memory is hot-plugged/hot-un-plugged. The support is currently limited to 64 bit systems. The bug was exposed when mappings for a device were actually hot-unplugged and plugged in back later. A similar issue was observed during the development of memtrace, but memtrace does it's own flushing of region via a custom routine. These patches do a flush both on hotplug/unplug to clear any stale data in the cache w.r.t mappings, there is a small race window where a clean cache line may be created again just prior to tearing down the mapping. The patches were tested by disabling the flush routines in memtrace and doing I/O on the trace file. The system immediately checkstops (quite reliablly if prior to the hot-unplug of the memtrace region, we memset the regions we are about to hot unplug). After these patches no custom flushing is needed in the memtrace code. Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Balbir Singh Acked-by: Reza Arbab Reviewed-by: Rashmica Gupta Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/mm/mem.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -143,6 +143,7 @@ int arch_add_memory(int nid, u64 start, start, start + size, rc); return -EFAULT; } + flush_inval_dcache_range(start, start + size); return __add_pages(nid, start_pfn, nr_pages, altmap, want_memblock); } @@ -169,6 +170,7 @@ int arch_remove_memory(u64 start, u64 si /* Remove htab bolted mappings for this section of memory */ start = (unsigned long)__va(start); + flush_inval_dcache_range(start, start + size); ret = remove_section_mapping(start, start + size); /* Ensure all vmalloc mappings are flushed in case they also