From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 1D8D46B0389 for ; Sat, 25 Feb 2017 16:00:27 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id b2so103572885pgc.6 for ; Sat, 25 Feb 2017 13:00:27 -0800 (PST) Received: from mail-pg0-x234.google.com (mail-pg0-x234.google.com. [2607:f8b0:400e:c05::234]) by mx.google.com with ESMTPS id n59si10976776plb.191.2017.02.25.13.00.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 25 Feb 2017 13:00:26 -0800 (PST) Received: by mail-pg0-x234.google.com with SMTP id p5so2667943pga.1 for ; Sat, 25 Feb 2017 13:00:26 -0800 (PST) From: 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org