From nobody Tue Jun 30 00:48:13 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D21FC433F5 for ; Fri, 28 Jan 2022 19:57:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351042AbiA1T5i (ORCPT ); Fri, 28 Jan 2022 14:57:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:49875 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351020AbiA1T5a (ORCPT ); Fri, 28 Jan 2022 14:57:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643399849; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=z7PkS3p7o3c1KlQT9mE47JFulyDrby+E1xl/snWb8i0=; b=ZmdZqs0qj1/Nqe1eOgebpdN7IIG08owjDtRMU0p6RzzEj3zqsHl0ZJYgokLJLTUx5QLAHa djCL3agpOZ5JGXg5FfHgkFw9ZGR6sd1qEeanYtnvyTpnquVThnBu0ojENNWZwZohprABjY wVfaluFUYc00bq6QlAdud4l8nV+TG8g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-463-iCC205RvNbe_8lZYT7eujw-1; Fri, 28 Jan 2022 14:57:26 -0500 X-MC-Unique: iCC205RvNbe_8lZYT7eujw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C9FE31083F6D; Fri, 28 Jan 2022 19:57:24 +0000 (UTC) Received: from llong.com (unknown [10.22.33.1]) by smtp.corp.redhat.com (Postfix) with ESMTP id D155C5DB82; Fri, 28 Jan 2022 19:57:23 +0000 (UTC) From: Waiman Long To: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Rafael Aquini , Waiman Long Subject: [PATCH 1/2] mm/page_owner: Introduce SNPRINTF() macro that includes length error check Date: Fri, 28 Jan 2022 14:56:41 -0500 Message-Id: <20220128195642.416743-2-longman@redhat.com> In-Reply-To: <20220128195642.416743-1-longman@redhat.com> References: <20220128195642.416743-1-longman@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" In print_page_owner(), there is a repetitive check after each snprintf() to make sure that the final length is less than the buffer size. Simplify the code and make it easier to read by embedding the buffer length check and increment inside the macro. Signed-off-by: Waiman Long --- mm/page_owner.c | 50 +++++++++++++++++++++++-------------------------- 1 file changed, 23 insertions(+), 27 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 99e360df9465..c52ce9d6bc3b 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -325,12 +325,20 @@ void pagetypeinfo_showmixedcount_print(struct seq_fil= e *m, seq_putc(m, '\n'); } =20 +#define SNPRINTF(_buf, _size, _len, _err, _fmt, ...) \ + do { \ + _len +=3D snprintf(_buf + _len, _size - _len, _fmt, \ + ##__VA_ARGS__); \ + if (_len >=3D _size) \ + goto _err; \ + } while (0) + static ssize_t print_page_owner(char __user *buf, size_t count, unsigned long pfn, struct page *page, struct page_owner *page_owner, depot_stack_handle_t handle) { - int ret, pageblock_mt, page_mt; + int ret =3D 0, pageblock_mt, page_mt; char *kbuf; =20 count =3D min_t(size_t, count, PAGE_SIZE); @@ -338,44 +346,32 @@ print_page_owner(char __user *buf, size_t count, unsi= gned long pfn, if (!kbuf) return -ENOMEM; =20 - ret =3D snprintf(kbuf, count, - "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_= ts %llu ns\n", - page_owner->order, page_owner->gfp_mask, - &page_owner->gfp_mask, page_owner->pid, - page_owner->ts_nsec, page_owner->free_ts_nsec); - - if (ret >=3D count) - goto err; + SNPRINTF(kbuf, count, ret, err, + "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_t= s %llu ns\n", + page_owner->order, page_owner->gfp_mask, + &page_owner->gfp_mask, page_owner->pid, + page_owner->ts_nsec, page_owner->free_ts_nsec); =20 /* Print information relevant to grouping pages by mobility */ pageblock_mt =3D get_pageblock_migratetype(page); page_mt =3D gfp_migratetype(page_owner->gfp_mask); - ret +=3D snprintf(kbuf + ret, count - ret, - "PFN %lu type %s Block %lu type %s Flags %pGp\n", - pfn, - migratetype_names[page_mt], - pfn >> pageblock_order, - migratetype_names[pageblock_mt], - &page->flags); - - if (ret >=3D count) - goto err; + SNPRINTF(kbuf, count, ret, err, + "PFN %lu type %s Block %lu type %s Flags %pGp\n", + pfn, migratetype_names[page_mt], + pfn >> pageblock_order, + migratetype_names[pageblock_mt], + &page->flags); =20 ret +=3D stack_depot_snprint(handle, kbuf + ret, count - ret, 0); if (ret >=3D count) goto err; =20 - if (page_owner->last_migrate_reason !=3D -1) { - ret +=3D snprintf(kbuf + ret, count - ret, + if (page_owner->last_migrate_reason !=3D -1) + SNPRINTF(kbuf, count, ret, err, "Page has been migrated, last migrate reason: %s\n", migrate_reason_names[page_owner->last_migrate_reason]); - if (ret >=3D count) - goto err; - } =20 - ret +=3D snprintf(kbuf + ret, count - ret, "\n"); - if (ret >=3D count) - goto err; + SNPRINTF(kbuf, count, ret, err, "\n"); =20 if (copy_to_user(buf, kbuf, ret)) ret =3D -EFAULT; --=20 2.27.0 From nobody Tue Jun 30 00:48:13 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D980BC433EF for ; Fri, 28 Jan 2022 19:57:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351084AbiA1T5q (ORCPT ); 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Fri, 28 Jan 2022 14:57:27 -0500 X-MC-Unique: GCdYn6EWP_Oq0PMNqG-U-w-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1D37A1083F68; Fri, 28 Jan 2022 19:57:26 +0000 (UTC) Received: from llong.com (unknown [10.22.33.1]) by smtp.corp.redhat.com (Postfix) with ESMTP id EFAE45DB82; Fri, 28 Jan 2022 19:57:24 +0000 (UTC) From: Waiman Long To: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Rafael Aquini , Waiman Long Subject: [PATCH 2/2] mm/page_owner: Dump memcg information Date: Fri, 28 Jan 2022 14:56:42 -0500 Message-Id: <20220128195642.416743-3-longman@redhat.com> In-Reply-To: <20220128195642.416743-1-longman@redhat.com> References: <20220128195642.416743-1-longman@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It was found that a number of offlined memcgs were not freed because they were pinned by some charged pages that were present. Even "echo 1 > /proc/sys/vm/drop_caches" wasn't able to free those pages. These offlined but not freed memcgs tend to increase in number over time with the side effect that percpu memory consumption as shown in /proc/meminfo also increases over time. In order to find out more information about those pages that pin offlined memcgs, the page_owner feature is extended to dump memory cgroup information especially whether the cgroup is offlined or not. Signed-off-by: Waiman Long --- mm/page_owner.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/mm/page_owner.c b/mm/page_owner.c index c52ce9d6bc3b..e5d8c642296b 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -10,6 +10,7 @@ #include #include #include +#include #include =20 #include "internal.h" @@ -339,6 +340,7 @@ print_page_owner(char __user *buf, size_t count, unsign= ed long pfn, depot_stack_handle_t handle) { int ret =3D 0, pageblock_mt, page_mt; + unsigned long __maybe_unused memcg_data; char *kbuf; =20 count =3D min_t(size_t, count, PAGE_SIZE); @@ -371,6 +373,32 @@ print_page_owner(char __user *buf, size_t count, unsig= ned long pfn, "Page has been migrated, last migrate reason: %s\n", migrate_reason_names[page_owner->last_migrate_reason]); =20 +#ifdef CONFIG_MEMCG + /* + * Look for memcg information and print it out + */ + memcg_data =3D READ_ONCE(page->memcg_data); + if (memcg_data) { + struct mem_cgroup *memcg =3D page_memcg_check(page); + bool onlined; + char name[80]; + + if (memcg_data & MEMCG_DATA_OBJCGS) + SNPRINTF(kbuf, count, ret, err, "Slab cache page\n"); + + if (!memcg) + goto copy_out; + + onlined =3D (memcg->css.flags & CSS_ONLINE); + cgroup_name(memcg->css.cgroup, name, sizeof(name) - 1); + SNPRINTF(kbuf, count, ret, err, "Charged %sto %smemcg %s\n", + PageMemcgKmem(page) ? "(via objcg) " : "", + onlined ? "" : "offlined ", name); + } + +copy_out: +#endif + SNPRINTF(kbuf, count, ret, err, "\n"); =20 if (copy_to_user(buf, kbuf, ret)) --=20 2.27.0