Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752596AbdGXXD3 (ORCPT ); Mon, 24 Jul 2017 19:03:29 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:51164 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756461AbdGXXCs (ORCPT ); Mon, 24 Jul 2017 19:02:48 -0400 From: Dennis Zhou To: Tejun Heo , Christoph Lameter , Josef Bacik CC: , , , Dennis Zhou Subject: [PATCH v2 10/23] percpu: change the number of pages marked in the first_chunk pop bitmap Date: Mon, 24 Jul 2017 19:02:07 -0400 Message-ID: <20170724230220.21774-11-dennisz@fb.com> X-Mailer: git-send-email 2.13.3 In-Reply-To: <20170724230220.21774-1-dennisz@fb.com> References: <20170724230220.21774-1-dennisz@fb.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [192.168.52.123] X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-24_14:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3450 Lines: 87 From: "Dennis Zhou (Facebook)" The populated bitmap represents the state of the pages the chunk serves. Prior, the bitmap was marked completely used as the first chunk was allocated and immutable. This is misleading because the first chunk may not be completely filled. Additionally, with moving the base_addr up in the previous patch, the population check no longer corresponds to what was being checked. This patch modifies the population map to be only the number of pages the region serves and to make what it was checking correspond correctly again. The change is to remove any misunderstanding between the size of the populated bitmap and the actual size of it. The work function page iterators now use nr_pages for the check rather than pcpu_unit_pages because nr_populated is now chunk specific. Without this, the work function would try to populate the remainder of these chunks despite it not serving any more than nr_pages when nr_pages is set less than pcpu_unit_pages. Signed-off-by: Dennis Zhou --- mm/percpu.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/mm/percpu.c b/mm/percpu.c index 5b1fcef..773dafe 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -737,7 +737,9 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr, region_size = PFN_ALIGN(start_offset + map_size); /* allocate chunk */ - chunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0); + chunk = memblock_virt_alloc(sizeof(struct pcpu_chunk) + + BITS_TO_LONGS(region_size >> PAGE_SHIFT), + 0); INIT_LIST_HEAD(&chunk->list); INIT_LIST_HEAD(&chunk->map_extend_list); @@ -746,15 +748,15 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr, chunk->start_offset = start_offset; chunk->end_offset = region_size - chunk->start_offset - map_size; - chunk->nr_pages = pcpu_unit_pages; + chunk->nr_pages = region_size >> PAGE_SHIFT; chunk->map = map; chunk->map_alloc = init_map_size; /* manage populated page bitmap */ chunk->immutable = true; - bitmap_fill(chunk->populated, pcpu_unit_pages); - chunk->nr_populated = pcpu_unit_pages; + bitmap_fill(chunk->populated, chunk->nr_pages); + chunk->nr_populated = chunk->nr_pages; chunk->contig_hint = chunk->free_size = map_size; @@ -1212,7 +1214,7 @@ static void pcpu_balance_workfn(struct work_struct *work) list_for_each_entry_safe(chunk, next, &to_free, list) { int rs, re; - pcpu_for_each_pop_region(chunk, rs, re, 0, pcpu_unit_pages) { + pcpu_for_each_pop_region(chunk, rs, re, 0, chunk->nr_pages) { pcpu_depopulate_chunk(chunk, rs, re); spin_lock_irq(&pcpu_lock); pcpu_chunk_depopulated(chunk, rs, re); @@ -1269,7 +1271,7 @@ static void pcpu_balance_workfn(struct work_struct *work) spin_lock_irq(&pcpu_lock); list_for_each_entry(chunk, &pcpu_slot[slot], list) { - nr_unpop = pcpu_unit_pages - chunk->nr_populated; + nr_unpop = chunk->nr_pages - chunk->nr_populated; if (nr_unpop) break; } @@ -1279,7 +1281,7 @@ static void pcpu_balance_workfn(struct work_struct *work) continue; /* @chunk can't go away while pcpu_alloc_mutex is held */ - pcpu_for_each_unpop_region(chunk, rs, re, 0, pcpu_unit_pages) { + pcpu_for_each_unpop_region(chunk, rs, re, 0, chunk->nr_pages) { int nr = min(re - rs, nr_to_pop); ret = pcpu_populate_chunk(chunk, rs, rs + nr); -- 2.9.3