From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 060/155] mm, memcg: fix build error around the usage of kmem_caches Date: Wed, 01 Apr 2020 21:06:30 -0700 Message-ID: <20200402040630.5wtvrtiGI%akpm@linux-foundation.org> References: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:56448 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725789AbgDBEGb (ORCPT ); Thu, 2 Apr 2020 00:06:31 -0400 In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, hannes@cmpxchg.org, laoar.shao@gmail.com, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, tj@kernel.org, torvalds@linux-foundation.org, vdavydov.dev@gmail.com From: Yafang Shao Subject: mm, memcg: fix build error around the usage of kmem_caches When I manually set default n to MEMCG_KMEM in init/Kconfig, bellow error occurs, mm/slab_common.c: In function 'memcg_slab_start': mm/slab_common.c:1530:30: error: 'struct mem_cgroup' has no member named 'kmem_caches' return seq_list_start(&memcg->kmem_caches, *pos); ^ mm/slab_common.c: In function 'memcg_slab_next': mm/slab_common.c:1537:32: error: 'struct mem_cgroup' has no member named 'kmem_caches' return seq_list_next(p, &memcg->kmem_caches, pos); ^ mm/slab_common.c: In function 'memcg_slab_show': mm/slab_common.c:1551:16: error: 'struct mem_cgroup' has no member named 'kmem_caches' if (p == memcg->kmem_caches.next) ^ CC arch/x86/xen/smp.o mm/slab_common.c: In function 'memcg_slab_start': mm/slab_common.c:1531:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ mm/slab_common.c: In function 'memcg_slab_next': mm/slab_common.c:1538:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ That's because kmem_caches is defined only when CONFIG_MEMCG_KMEM is set, while memcg_slab_start() will use it no matter CONFIG_MEMCG_KMEM is defined or not. By the way, the reason I mannuly undefined CONFIG_MEMCG_KMEM is to verify whether my some other code change is still stable when CONFIG_MEMCG_KMEM is not set. Unfortunately, the existing code has been already unstable since v4.11. Link: http://lkml.kernel.org/r/1580970260-2045-1-git-send-email-laoar.shao@gmail.com Fixes: bc2791f857e1 ("slab: link memcg kmem_caches on their associated memory cgroup") Signed-off-by: Yafang Shao Acked-by: Andrew Morton Cc: Tejun Heo Cc: Vladimir Davydov Cc: Johannes Weiner Cc: Michal Hocko Signed-off-by: Andrew Morton --- mm/memcontrol.c | 3 ++- mm/slab_common.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) --- a/mm/memcontrol.c~mm-memcg-fix-build-error-around-the-usage-of-kmem_caches +++ a/mm/memcontrol.c @@ -4792,7 +4792,8 @@ static struct cftype mem_cgroup_legacy_f .write = mem_cgroup_reset, .read_u64 = mem_cgroup_read_u64, }, -#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG) +#if defined(CONFIG_MEMCG_KMEM) && \ + (defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)) { .name = "kmem.slabinfo", .seq_start = memcg_slab_start, --- a/mm/slab_common.c~mm-memcg-fix-build-error-around-the-usage-of-kmem_caches +++ a/mm/slab_common.c @@ -1521,7 +1521,7 @@ void dump_unreclaimable_slab(void) mutex_unlock(&slab_mutex); } -#if defined(CONFIG_MEMCG) +#if defined(CONFIG_MEMCG_KMEM) void *memcg_slab_start(struct seq_file *m, loff_t *pos) { struct mem_cgroup *memcg = mem_cgroup_from_seq(m); _