From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Pingfan Liu Subject: [PATCHv2 3/3] powerpc/numa: make all possible node be instanced against NULL reference in node_zonelist() Date: Thu, 20 Dec 2018 17:50:39 +0800 Message-Id: <1545299439-31370-4-git-send-email-kernelfans@gmail.com> In-Reply-To: <1545299439-31370-1-git-send-email-kernelfans@gmail.com> References: <1545299439-31370-1-git-send-email-kernelfans@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-mm@kvack.org Cc: Pingfan Liu , linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Michal Hocko , Vlastimil Babka , Mike Rapoport , Bjorn Helgaas , Jonathan Cameron , David Rientjes , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman List-ID: This patch tries to resolve a bug rooted at mm when using nr_cpus. It was reported at [1]. The root cause is: device->numa_node info is used as preferred_nid param for __alloc_pages_nodemask(), which causes NULL reference when ac->zonelist = node_zonelist(preferred_nid, gfp_mask), due to the preferred_nid is not online and not instanced. Hence the bug affects all archs if a machine having a memory less numa-node, but a device on the node is used and provide numa_node info to __alloc_pages_nodemask(). This patch makes all possible node online for ppc. [1]: https://lore.kernel.org/patchwork/patch/1020838/ Signed-off-by: Pingfan Liu Cc: linuxppc-dev@lists.ozlabs.org Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Cc: Andrew Morton Cc: Michal Hocko Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Bjorn Helgaas Cc: Jonathan Cameron Cc: David Rientjes Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman --- Note: [1-2/3] implements one way to fix the bug, while this patch tries another way. Hence using this patch when [1-2/3] is not acceptable. arch/powerpc/mm/numa.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index ce28ae5..31d81a4 100644 --- a/arch/powerpc/mm/numa.c +++ b/arch/powerpc/mm/numa.c @@ -864,10 +864,19 @@ void __init initmem_init(void) memblock_dump_all(); - for_each_online_node(nid) { + /* Instance all possible nodes to overcome potential NULL reference + * issue on node_zonelist() when using nr_cpus + */ + for_each_node(nid) { unsigned long start_pfn, end_pfn; - get_pfn_range_for_nid(nid, &start_pfn, &end_pfn); + if (node_online(nid)) + get_pfn_range_for_nid(nid, &start_pfn, &end_pfn); + else { + start_pfn = end_pfn = 0; + /* online it, so later zonelists[] will be built */ + node_set_online(nid); + } setup_node_data(nid, start_pfn, end_pfn); sparse_memory_present_with_active_regions(nid); } -- 2.7.4