From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f42.google.com (mail-pa0-f42.google.com [209.85.220.42]) by kanga.kvack.org (Postfix) with ESMTP id 746286B00DC for ; Thu, 13 Nov 2014 04:12:52 -0500 (EST) Received: by mail-pa0-f42.google.com with SMTP id et14so148314pad.1 for ; Thu, 13 Nov 2014 01:12:52 -0800 (PST) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id zt3si11231652pbc.97.2014.11.13.01.12.50 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Nov 2014 01:12:51 -0800 (PST) From: Vladimir Davydov Subject: [PATCH -mm 1/2] memcg: only check memcg_kmem_skip_account in __memcg_kmem_get_cache Date: Thu, 13 Nov 2014 12:12:42 +0300 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org __memcg_kmem_get_cache can recurse if it calls kmalloc (which it does if the cgroup's kmem cache doesn't exist), because kmalloc may call __memcg_kmem_get_cache internally again. To avoid the recursion, we use the task_struct->memcg_kmem_skip_account flag. However, there's no need checking the flag in memcg_kmem_newpage_charge, because there's no way how this function could result in recursion, if called from memcg_kmem_get_cache. So let's remove the redundant code. Signed-off-by: Vladimir Davydov --- mm/memcontrol.c | 28 ---------------------------- 1 file changed, 28 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index bb8c237026cc..d9fab72da52e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2905,34 +2905,6 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order) *_memcg = NULL; - /* - * Disabling accounting is only relevant for some specific memcg - * internal allocations. Therefore we would initially not have such - * check here, since direct calls to the page allocator that are - * accounted to kmemcg (alloc_kmem_pages and friends) only happen - * outside memcg core. We are mostly concerned with cache allocations, - * and by having this test at memcg_kmem_get_cache, we are already able - * to relay the allocation to the root cache and bypass the memcg cache - * altogether. - * - * There is one exception, though: the SLUB allocator does not create - * large order caches, but rather service large kmallocs directly from - * the page allocator. Therefore, the following sequence when backed by - * the SLUB allocator: - * - * memcg_stop_kmem_account(); - * kmalloc() - * memcg_resume_kmem_account(); - * - * would effectively ignore the fact that we should skip accounting, - * since it will drive us directly to this function without passing - * through the cache selector memcg_kmem_get_cache. Such large - * allocations are extremely rare but can happen, for instance, for the - * cache arrays. We bring this test here. - */ - if (current->memcg_kmem_skip_account) - return true; - memcg = get_mem_cgroup_from_mm(current->mm); if (!memcg_kmem_is_active(memcg)) { -- 1.7.10.4 -- 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