From patchwork Fri Mar 5 12:22:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 394272 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22380C43603 for ; Fri, 5 Mar 2021 12:44:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0428A65037 for ; Fri, 5 Mar 2021 12:44:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233603AbhCEMo3 (ORCPT ); Fri, 5 Mar 2021 07:44:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:33462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229758AbhCEMn5 (ORCPT ); Fri, 5 Mar 2021 07:43:57 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2059B65023; Fri, 5 Mar 2021 12:43:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614948236; bh=R4bQGT+EhdO1aEwW3pjSD0CXYECki5UlPhzxon6x528=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kuoH8OxZ86UpnmJNCWMY3kBf6vrQHjHsAyjorqAPhz771/xW9C4bLlE1AeQ/4nylx p35FvGa6smPYnu0omOr0r8QAB7PyjKwWXrz9h/Ftof7xzCR1SyYNt1T8E9H+N1UypY FIntHlxmJdSK8eXxICKpzfLg/mQ1pchc0kcuSu+Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rokudo Yan , Minchan Kim , Sergey Senozhatsky , Andrew Morton , Linus Torvalds Subject: [PATCH 4.4 28/30] zsmalloc: account the number of compacted pages correctly Date: Fri, 5 Mar 2021 13:22:57 +0100 Message-Id: <20210305120850.810821375@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210305120849.381261651@linuxfoundation.org> References: <20210305120849.381261651@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rokudo Yan commit 2395928158059b8f9858365fce7713ce7fef62e4 upstream. There exists multiple path may do zram compaction concurrently. 1. auto-compaction triggered during memory reclaim 2. userspace utils write zram/compaction node So, multiple threads may call zs_shrinker_scan/zs_compact concurrently. But pages_compacted is a per zsmalloc pool variable and modification of the variable is not serialized(through under class->lock). There are two issues here: 1. the pages_compacted may not equal to total number of pages freed(due to concurrently add). 2. zs_shrinker_scan may not return the correct number of pages freed(issued by current shrinker). The fix is simple: 1. account the number of pages freed in zs_compact locally. 2. use actomic variable pages_compacted to accumulate total number. Link: https://lkml.kernel.org/r/20210202122235.26885-1-wu-yan@tcl.com Fixes: 860c707dca155a56 ("zsmalloc: account the number of compacted pages") Signed-off-by: Rokudo Yan Cc: Minchan Kim Cc: Sergey Senozhatsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/block/zram/zram_drv.c | 2 +- include/linux/zsmalloc.h | 2 +- mm/zsmalloc.c | 17 +++++++++++------ 3 files changed, 13 insertions(+), 8 deletions(-) --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -450,7 +450,7 @@ static ssize_t mm_stat_show(struct devic zram->limit_pages << PAGE_SHIFT, max_used << PAGE_SHIFT, (u64)atomic64_read(&zram->stats.zero_pages), - pool_stats.pages_compacted); + atomic_long_read(&pool_stats.pages_compacted)); up_read(&zram->init_lock); return ret; --- a/include/linux/zsmalloc.h +++ b/include/linux/zsmalloc.h @@ -36,7 +36,7 @@ enum zs_mapmode { struct zs_pool_stats { /* How many pages were migrated (freed) */ - unsigned long pages_compacted; + atomic_long_t pages_compacted; }; struct zs_pool; --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1745,11 +1745,13 @@ static unsigned long zs_can_compact(stru return obj_wasted * class->pages_per_zspage; } -static void __zs_compact(struct zs_pool *pool, struct size_class *class) +static unsigned long __zs_compact(struct zs_pool *pool, + struct size_class *class) { struct zs_compact_control cc; struct page *src_page; struct page *dst_page = NULL; + unsigned long pages_freed = 0; spin_lock(&class->lock); while ((src_page = isolate_source_page(class))) { @@ -1780,7 +1782,7 @@ static void __zs_compact(struct zs_pool putback_zspage(pool, class, dst_page); if (putback_zspage(pool, class, src_page) == ZS_EMPTY) - pool->stats.pages_compacted += class->pages_per_zspage; + pages_freed += class->pages_per_zspage; spin_unlock(&class->lock); cond_resched(); spin_lock(&class->lock); @@ -1790,12 +1792,15 @@ static void __zs_compact(struct zs_pool putback_zspage(pool, class, src_page); spin_unlock(&class->lock); + + return pages_freed; } unsigned long zs_compact(struct zs_pool *pool) { int i; struct size_class *class; + unsigned long pages_freed = 0; for (i = zs_size_classes - 1; i >= 0; i--) { class = pool->size_class[i]; @@ -1803,10 +1808,11 @@ unsigned long zs_compact(struct zs_pool continue; if (class->index != i) continue; - __zs_compact(pool, class); + pages_freed += __zs_compact(pool, class); } + atomic_long_add(pages_freed, &pool->stats.pages_compacted); - return pool->stats.pages_compacted; + return pages_freed; } EXPORT_SYMBOL_GPL(zs_compact); @@ -1823,13 +1829,12 @@ static unsigned long zs_shrinker_scan(st struct zs_pool *pool = container_of(shrinker, struct zs_pool, shrinker); - pages_freed = pool->stats.pages_compacted; /* * Compact classes and calculate compaction delta. * Can run concurrently with a manually triggered * (by user) compaction. */ - pages_freed = zs_compact(pool) - pages_freed; + pages_freed = zs_compact(pool); return pages_freed ? pages_freed : SHRINK_STOP; }