From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 8A1896B0010 for ; Fri, 6 Jul 2018 15:07:21 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id e1-v6so5146609pld.23 for ; Fri, 06 Jul 2018 12:07:21 -0700 (PDT) Received: from mga04.intel.com (mga04.intel.com. [192.55.52.120]) by mx.google.com with ESMTPS id n6-v6si5541394pla.398.2018.07.06.12.07.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Jul 2018 12:07:20 -0700 (PDT) From: Ross Zwisler Subject: [PATCH] mm/sparse.c: fix error path in sparse_add_one_section Date: Fri, 6 Jul 2018 13:06:58 -0600 Message-Id: <20180706190658.6873-1-ross.zwisler@linux.intel.com> in-reply-to: Sender: owner-linux-mm@kvack.org List-ID: To: pasha.tatashin@oracle.com, linux-nvdimm@lists.01.org Cc: Ross Zwisler , osalvador@techadventures.net, bhe@redhat.com, Dave Hansen , LKML , Linux MM , Michal Hocko , Vlastimil Babka , Andrew Morton , "Kirill A. Shutemov" , osalvador@suse.de The following commit in -next: commit 054620849110 ("mm/sparse.c: make sparse_init_one_section void and remove check") changed how the error handling in sparse_add_one_section() works. Previously sparse_index_init() could return -EEXIST, and the function would continue on happily. 'ret' would get unconditionally overwritten by the result from sparse_init_one_section() and the error code after the 'out:' label wouldn't be triggered. With the above referenced commit, though, an -EEXIST error return from sparse_index_init() now takes us through the function and into the error case after 'out:'. This eventually causes a kernel BUG, probably because we've just freed a memory section that we successfully set up and marked as present: BUG: unable to handle kernel paging request at ffffea0005000080 RIP: 0010:memmap_init_zone+0x154/0x1cf Call Trace: move_pfn_range_to_zone+0x168/0x180 devm_memremap_pages+0x29b/0x480 pmem_attach_disk+0x1ae/0x6c0 [nd_pmem] ? devm_memremap+0x79/0xb0 nd_pmem_probe+0x7e/0xa0 [nd_pmem] nvdimm_bus_probe+0x6e/0x160 [libnvdimm] driver_probe_device+0x310/0x480 __device_attach_driver+0x86/0x100 ? __driver_attach+0x110/0x110 bus_for_each_drv+0x6e/0xb0 __device_attach+0xe2/0x160 device_initial_probe+0x13/0x20 bus_probe_device+0xa6/0xc0 device_add+0x41b/0x660 ? lock_acquire+0xa3/0x210 nd_async_device_register+0x12/0x40 [libnvdimm] async_run_entry_fn+0x3e/0x170 process_one_work+0x230/0x680 worker_thread+0x3f/0x3b0 kthread+0x12f/0x150 ? process_one_work+0x680/0x680 ? kthread_create_worker_on_cpu+0x70/0x70 ret_from_fork+0x3a/0x50 Fix this by clearing 'ret' back to 0 if sparse_index_init() returns -EEXIST. This restores the previous behavior. Signed-off-by: Ross Zwisler --- mm/sparse.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/sparse.c b/mm/sparse.c index 9574113fc745..d254bd2d3289 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -753,8 +753,12 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat, * plus, it does a kmalloc */ ret = sparse_index_init(section_nr, pgdat->node_id); - if (ret < 0 && ret != -EEXIST) - return ret; + if (ret < 0) { + if (ret == -EEXIST) + ret = 0; + else + return ret; + } memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, altmap); if (!memmap) return -ENOMEM; -- 2.14.4