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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5702FC433EF for ; Wed, 2 Mar 2022 23:34:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C643E8D0002; Wed, 2 Mar 2022 18:34:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BEA808D0001; Wed, 2 Mar 2022 18:34:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A8CD78D0002; Wed, 2 Mar 2022 18:34:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id 932418D0001 for ; Wed, 2 Mar 2022 18:34:37 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 5226F801A0 for ; Wed, 2 Mar 2022 23:34:37 +0000 (UTC) X-FDA: 79201052994.14.EE27877 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf30.hostedemail.com (Postfix) with ESMTP id CFCE080011 for ; Wed, 2 Mar 2022 23:34:35 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id CF5DB61B32; Wed, 2 Mar 2022 23:34:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21B2BC004E1; Wed, 2 Mar 2022 23:34:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1646264074; bh=cBDUYSR0eSGUbg7hhpGZJrrV34Qa8/yXz+XpHML8nss=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=1JgUhuuJ/QdaNR6BRFyaTi/ih7S/l6BxWJXA4fT24VBaELET4VCQ9vB71VbPFT/GS dyeDNzKASdloj8ZLaW7y7Jy3FTu5nuSqQZdDnRYPa1Lnq265vm4xVSNFKco51K7+LP FxiI+rdxk6OH7GnAii5jnvynPZAl2pRTk2jyEC3Q= Date: Wed, 2 Mar 2022 15:34:33 -0800 From: Andrew Morton To: wangjianxing Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] mm/page_alloc: add scheduling point to free_unref_page_list Message-Id: <20220302153433.719caef31bd9e99319c5e6a2@linux-foundation.org> In-Reply-To: <20220302013825.2290315-1-wangjianxing@loongson.cn> References: <20220302013825.2290315-1-wangjianxing@loongson.cn> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CFCE080011 X-Rspam-User: Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=1JgUhuuJ; spf=pass (imf30.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Stat-Signature: urg3pzqepmx11dbpt8nan71kbugr5ooc X-HE-Tag: 1646264075-265598 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 1 Mar 2022 20:38:25 -0500 wangjianxing wrote: > free a large list of pages maybe cause rcu_sched starved on > non-preemptible kernels > > rcu: rcu_sched kthread starved for 5359 jiffies! g454793 f0x0 > RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=19 > [...] > Call Trace: > free_unref_page_list+0x19c/0x270 > release_pages+0x3cc/0x498 > tlb_flush_mmu_free+0x44/0x70 > zap_pte_range+0x450/0x738 > unmap_page_range+0x108/0x240 > unmap_vmas+0x74/0xf0 > unmap_region+0xb0/0x120 > do_munmap+0x264/0x438 > vm_munmap+0x58/0xa0 > sys_munmap+0x10/0x20 > syscall_common+0x24/0x38 Thanks. How did this large list of pages come about? Will people be seeing this message in upstream kernels, or is it specific to some caller code which you have added? Please always include details such as this so that others can determine whether the fix should be backported into -stable kernels.