From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752079AbdBYVA6 (ORCPT ); Sat, 25 Feb 2017 16:00:58 -0500 Received: from mail-pg0-f45.google.com ([74.125.83.45]:34652 "EHLO mail-pg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986AbdBYVAz (ORCPT ); Sat, 25 Feb 2017 16:00:55 -0500 From: Tahsin Erdogan To: Tejun Heo , Christoph Lameter , Andrew Morton , Chris Wilson , Andrey Ryabinin , Roman Pen , Joonas Lahtinen , Michal Hocko , zijun_hu , Joonsoo Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Tahsin Erdogan Subject: [PATCH 2/3] percpu: acquire pcpu_lock when updating pcpu_nr_empty_pop_pages Date: Sat, 25 Feb 2017 13:00:19 -0800 Message-Id: <20170225210019.23610-1-tahsin@google.com> X-Mailer: git-send-email 2.11.0.483.g087da7b7c-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Update to pcpu_nr_empty_pop_pages in pcpu_alloc() is currently done without holding pcpu_lock. This can lead to bad updates to the variable. Add missing lock calls. Fixes: b539b87fed37 ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated") Signed-off-by: Tahsin Erdogan --- mm/percpu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/percpu.c b/mm/percpu.c index 0686f566d347..232356a2d914 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -1011,8 +1011,11 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved, mutex_unlock(&pcpu_alloc_mutex); } - if (chunk != pcpu_reserved_chunk) + if (chunk != pcpu_reserved_chunk) { + spin_lock_irqsave(&pcpu_lock, flags); pcpu_nr_empty_pop_pages -= occ_pages; + spin_unlock_irqrestore(&pcpu_lock, flags); + } if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW) pcpu_schedule_balance_work(); -- 2.11.0.483.g087da7b7c-goog