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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E5055C433B4 for ; Sun, 4 Apr 2021 17:06:22 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BC3C76128B for ; Sun, 4 Apr 2021 17:06:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BC3C76128B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=csgroup.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FD0Yl6qd5z3byx for ; Mon, 5 Apr 2021 03:06:19 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FD0YM3XRbz2yyx for ; Mon, 5 Apr 2021 03:05:54 +1000 (AEST) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4FD0Y82fMyz9txtD; Sun, 4 Apr 2021 19:05:48 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id x2rDN5V69KRg; Sun, 4 Apr 2021 19:05:48 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4FD0Y80xvSz9txtB; Sun, 4 Apr 2021 19:05:48 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id AB7A08B78E; Sun, 4 Apr 2021 19:05:51 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id SL43VzMhlW0d; Sun, 4 Apr 2021 19:05:51 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 15B408B76A; Sun, 4 Apr 2021 19:05:51 +0200 (CEST) Subject: Re: [PATCH v2] powerpc/mm: Add cond_resched() while removing hpte mappings To: Vaibhav Jain , linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org References: <20210404163148.321346-1-vaibhav@linux.ibm.com> From: Christophe Leroy Message-ID: Date: Sun, 4 Apr 2021 19:05:48 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210404163148.321346-1-vaibhav@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Aneesh Kumar K . V" , Dan Williams , Ira Weiny , Santosh Sivaraj Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 04/04/2021 à 18:31, Vaibhav Jain a écrit : > While removing large number of mappings from hash page tables for > large memory systems as soft-lockup is reported because of the time > spent inside htap_remove_mapping() like one below: > > watchdog: BUG: soft lockup - CPU#8 stuck for 23s! > > NIP plpar_hcall+0x38/0x58 > LR pSeries_lpar_hpte_invalidate+0x68/0xb0 > Call Trace: > 0x1fffffffffff000 (unreliable) > pSeries_lpar_hpte_removebolted+0x9c/0x230 > hash__remove_section_mapping+0xec/0x1c0 > remove_section_mapping+0x28/0x3c > arch_remove_memory+0xfc/0x150 > devm_memremap_pages_release+0x180/0x2f0 > devm_action_release+0x30/0x50 > release_nodes+0x28c/0x300 > device_release_driver_internal+0x16c/0x280 > unbind_store+0x124/0x170 > drv_attr_store+0x44/0x60 > sysfs_kf_write+0x64/0x90 > kernfs_fop_write+0x1b0/0x290 > __vfs_write+0x3c/0x70 > vfs_write+0xd4/0x270 > ksys_write+0xdc/0x130 > system_call+0x5c/0x70 > > Fix this by adding a cond_resched() to the loop in > htap_remove_mapping() that issues hcall to remove hpte mapping. The > call to cond_resched() is issued every HZ jiffies which should prevent > the soft-lockup from being reported. > > Suggested-by: Aneesh Kumar K.V > Signed-off-by: Vaibhav Jain Reviewed-by: Christophe Leroy > > --- > Changelog: > > v2: Issue cond_resched() every HZ jiffies instead of each iteration of > the loop. [ Christophe Leroy ] > --- > arch/powerpc/mm/book3s64/hash_utils.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c > index 581b20a2feaf..286e7e8cb919 100644 > --- a/arch/powerpc/mm/book3s64/hash_utils.c > +++ b/arch/powerpc/mm/book3s64/hash_utils.c > @@ -338,7 +338,7 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend, > int htab_remove_mapping(unsigned long vstart, unsigned long vend, > int psize, int ssize) > { > - unsigned long vaddr; > + unsigned long vaddr, time_limit; > unsigned int step, shift; > int rc; > int ret = 0; > @@ -351,8 +351,19 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend, > > /* Unmap the full range specificied */ > vaddr = ALIGN_DOWN(vstart, step); > + time_limit = jiffies + HZ; > + > for (;vaddr < vend; vaddr += step) { > rc = mmu_hash_ops.hpte_removebolted(vaddr, psize, ssize); > + > + /* > + * For large number of mappings introduce a cond_resched() > + * to prevent softlockup warnings. > + */ > + if (time_after(jiffies, time_limit)) { > + cond_resched(); > + time_limit = jiffies + HZ; > + } > if (rc == -ENOENT) { > ret = -ENOENT; > continue; >