From mboxrd@z Thu Jan 1 00:00:00 1970 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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 2D8C1C43460 for ; Mon, 3 May 2021 16:36:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3E806121D for ; Mon, 3 May 2021 16:36:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231548AbhECQhl (ORCPT ); Mon, 3 May 2021 12:37:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:37872 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231533AbhECQgq (ORCPT ); Mon, 3 May 2021 12:36:46 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CD996613C6; Mon, 3 May 2021 16:35:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620059751; bh=2O7tphoou+aLJvnaHD3D0IEYD6efTrjati1ZbhVx6cQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Gx05Gged6YS0ydjZfCaCsghyW52Uv16qhxnwKZ3wiFwpJMtDf/I7nZFveuZxW6L71 hQZEWhUInzgdwVzs0K2pipqL5cJjKTWIQa7VjhvfGm37G43mA1mKwPis7RRSvFACjG 7OFxj28ksLVVLPT6YMrbfSHI1UIl0vmQhKPB1cMtK0aMllmHkJ0PdeI6e9vkpEQiy+ dFY0DPQoqLZA9W8wu6hiyD45lcp/g8NCz2zWHc5JyLg0iyRW6KsUrJQAq6bCfNHCK7 MfGDAcRGMN/CD+V2rLpFUvoFxSSIwnamIlb6CRm2AuLVHZdU+3hGNoe99p5oCuEWl2 HDe71a9Wq0Leg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Uladzislau Rezki (Sony)" , "Paul E . McKenney" , Sasha Levin , rcu@vger.kernel.org Subject: [PATCH AUTOSEL 5.12 024/134] kvfree_rcu: Use same set of GFP flags as does single-argument Date: Mon, 3 May 2021 12:33:23 -0400 Message-Id: <20210503163513.2851510-24-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210503163513.2851510-1-sashal@kernel.org> References: <20210503163513.2851510-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Uladzislau Rezki (Sony)" [ Upstream commit ee6ddf58475cce8a3d3697614679cd8cb4a6f583 ] Running an rcuscale stress-suite can lead to "Out of memory" of a system. This can happen under high memory pressure with a small amount of physical memory. For example, a KVM test configuration with 64 CPUs and 512 megabytes can result in OOM when running rcuscale with below parameters: ../kvm.sh --torture rcuscale --allcpus --duration 10 --kconfig CONFIG_NR_CPUS=64 \ --bootargs "rcuscale.kfree_rcu_test=1 rcuscale.kfree_nthreads=16 rcuscale.holdoff=20 \ rcuscale.kfree_loops=10000 torture.disable_onoff_at_boot" --trust-make [ 12.054448] kworker/1:1H invoked oom-killer: gfp_mask=0x2cc0(GFP_KERNEL|__GFP_NOWARN), order=0, oom_score_adj=0 [ 12.055303] CPU: 1 PID: 377 Comm: kworker/1:1H Not tainted 5.11.0-rc3+ #510 [ 12.055416] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014 [ 12.056485] Workqueue: events_highpri fill_page_cache_func [ 12.056485] Call Trace: [ 12.056485] dump_stack+0x57/0x6a [ 12.056485] dump_header+0x4c/0x30a [ 12.056485] ? del_timer_sync+0x20/0x30 [ 12.056485] out_of_memory.cold.47+0xa/0x7e [ 12.056485] __alloc_pages_slowpath.constprop.123+0x82f/0xc00 [ 12.056485] __alloc_pages_nodemask+0x289/0x2c0 [ 12.056485] __get_free_pages+0x8/0x30 [ 12.056485] fill_page_cache_func+0x39/0xb0 [ 12.056485] process_one_work+0x1ed/0x3b0 [ 12.056485] ? process_one_work+0x3b0/0x3b0 [ 12.060485] worker_thread+0x28/0x3c0 [ 12.060485] ? process_one_work+0x3b0/0x3b0 [ 12.060485] kthread+0x138/0x160 [ 12.060485] ? kthread_park+0x80/0x80 [ 12.060485] ret_from_fork+0x22/0x30 [ 12.062156] Mem-Info: [ 12.062350] active_anon:0 inactive_anon:0 isolated_anon:0 [ 12.062350] active_file:0 inactive_file:0 isolated_file:0 [ 12.062350] unevictable:0 dirty:0 writeback:0 [ 12.062350] slab_reclaimable:2797 slab_unreclaimable:80920 [ 12.062350] mapped:1 shmem:2 pagetables:8 bounce:0 [ 12.062350] free:10488 free_pcp:1227 free_cma:0 ... [ 12.101610] Out of memory and no killable processes... [ 12.102042] Kernel panic - not syncing: System is deadlocked on memory [ 12.102583] CPU: 1 PID: 377 Comm: kworker/1:1H Not tainted 5.11.0-rc3+ #510 [ 12.102600] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014 Because kvfree_rcu() has a fallback path, memory allocation failure is not the end of the world. Furthermore, the added overhead of aggressive GFP settings must be balanced against the overhead of the fallback path, which is a cache miss for double-argument kvfree_rcu() and a call to synchronize_rcu() for single-argument kvfree_rcu(). The current choice of GFP_KERNEL|__GFP_NOWARN can result in longer latencies than a call to synchronize_rcu(), so less-tenacious GFP flags would be helpful. Here is the tradeoff that must be balanced: a) Minimize use of the fallback path, b) Avoid pushing the system into OOM, c) Bound allocation latency to that of synchronize_rcu(), and d) Leave the emergency reserves to use cases lacking fallbacks. This commit therefore changes GFP flags from GFP_KERNEL|__GFP_NOWARN to GFP_KERNEL|__GFP_NORETRY|__GFP_NOMEMALLOC|__GFP_NOWARN. This combination leaves the emergency reserves alone and can initiate reclaim, but will not invoke the OOM killer. Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index da6f5213fb74..2a739c5fcca5 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3464,7 +3464,7 @@ static void fill_page_cache_func(struct work_struct *work) for (i = 0; i < rcu_min_cached_objs; i++) { bnode = (struct kvfree_rcu_bulk_data *) - __get_free_page(GFP_KERNEL | __GFP_NOWARN); + __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); if (bnode) { raw_spin_lock_irqsave(&krcp->lock, flags); -- 2.30.2