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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 5A459C433E0 for ; Thu, 9 Jul 2020 13:30:14 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 144452065D for ; Thu, 9 Jul 2020 13:30:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 144452065D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4B2cVW4B5vzDqsQ for ; Thu, 9 Jul 2020 23:30:11 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=aneesh.kumar@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 4B2cGY2f97zDr6t for ; Thu, 9 Jul 2020 23:19:49 +1000 (AEST) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 069D2Und010170; Thu, 9 Jul 2020 09:19:44 -0400 Received: from ppma03dal.us.ibm.com (b.bd.3ea9.ip4.static.sl-reverse.com [169.62.189.11]) by mx0a-001b2d01.pphosted.com with ESMTP id 325n5xqu5f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 09 Jul 2020 09:19:44 -0400 Received: from pps.filterd (ppma03dal.us.ibm.com [127.0.0.1]) by ppma03dal.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 069DFVrA022087; Thu, 9 Jul 2020 13:19:43 GMT Received: from b03cxnp08026.gho.boulder.ibm.com (b03cxnp08026.gho.boulder.ibm.com [9.17.130.18]) by ppma03dal.us.ibm.com with ESMTP id 325k1mr17g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 09 Jul 2020 13:19:43 +0000 Received: from b03ledav002.gho.boulder.ibm.com (b03ledav002.gho.boulder.ibm.com [9.17.130.233]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 069DJdFS31588672 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 9 Jul 2020 13:19:39 GMT Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 36CB213604F; Thu, 9 Jul 2020 13:19:42 +0000 (GMT) Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B75A7136051; Thu, 9 Jul 2020 13:19:40 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.199.62.107]) by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 9 Jul 2020 13:19:40 +0000 (GMT) From: "Aneesh Kumar K.V" To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au Subject: [PATCH v3 3/4] powerpc/mm/radix: Remove split_kernel_mapping() Date: Thu, 9 Jul 2020 18:49:24 +0530 Message-Id: <20200709131925.922266-4-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200709131925.922266-1-aneesh.kumar@linux.ibm.com> References: <20200709131925.922266-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-09_07:2020-07-09, 2020-07-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=2 bulkscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 mlxlogscore=999 clxscore=1015 phishscore=0 spamscore=0 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007090097 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" , Bharata B Rao Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Bharata B Rao We split the page table mapping on memory unplug if the linear range was mapped with huge page mapping (for ex: 1G) The page table splitting code has a few issues: 1. Recursive locking -------------------- Memory unplug path takes cpu_hotplug_lock and calls stop_machine() for splitting the mappings. However stop_machine() takes cpu_hotplug_lock again causing deadlock. 2. BUG: sleeping function called from in_atomic() context --------------------------------------------------------- Memory unplug path (remove_pagetable) takes init_mm.page_table_lock spinlock and later calls stop_machine() which does wait_for_completion() 3. Bad unlock unbalance ----------------------- Memory unplug path takes init_mm.page_table_lock spinlock and calls stop_machine(). The stop_machine thread function runs in a different thread context (migration thread) which tries to release and reaquire ptl. Releasing ptl from a different thread than which acquired it causes bad unlock unbalance. These problems can be avoided if we avoid mapping hot-plugged memory with 1G mapping, thereby removing the need for splitting them during unplug. The kernel always make sure the minimum unplug request is SUBSECTION_SIZE for device memory and SECTION_SIZE for regular memory. In preparation for such a change remove page table splitting support. This essentially is a revert of commit 4dd5f8a99e791 ("powerpc/mm/radix: Split linear mapping on hot-unplug") Signed-off-by: Bharata B Rao Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/mm/book3s64/radix_pgtable.c | 95 +++++------------------- 1 file changed, 19 insertions(+), 76 deletions(-) diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c index 46ad2da3087a..d5a01b9aadc9 100644 --- a/arch/powerpc/mm/book3s64/radix_pgtable.c +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -15,7 +15,6 @@ #include #include #include -#include #include #include @@ -722,32 +721,6 @@ static void free_pud_table(pud_t *pud_start, p4d_t *p4d) p4d_clear(p4d); } -struct change_mapping_params { - pte_t *pte; - unsigned long start; - unsigned long end; - unsigned long aligned_start; - unsigned long aligned_end; -}; - -static int __meminit stop_machine_change_mapping(void *data) -{ - struct change_mapping_params *params = - (struct change_mapping_params *)data; - - if (!data) - return -1; - - spin_unlock(&init_mm.page_table_lock); - pte_clear(&init_mm, params->aligned_start, params->pte); - create_physical_mapping(__pa(params->aligned_start), - __pa(params->start), -1, PAGE_KERNEL); - create_physical_mapping(__pa(params->end), __pa(params->aligned_end), - -1, PAGE_KERNEL); - spin_lock(&init_mm.page_table_lock); - return 0; -} - static void remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end) { @@ -776,52 +749,6 @@ static void remove_pte_table(pte_t *pte_start, unsigned long addr, } } -/* - * clear the pte and potentially split the mapping helper - */ -static void __meminit split_kernel_mapping(unsigned long addr, unsigned long end, - unsigned long size, pte_t *pte) -{ - unsigned long mask = ~(size - 1); - unsigned long aligned_start = addr & mask; - unsigned long aligned_end = addr + size; - struct change_mapping_params params; - bool split_region = false; - - if ((end - addr) < size) { - /* - * We're going to clear the PTE, but not flushed - * the mapping, time to remap and flush. The - * effects if visible outside the processor or - * if we are running in code close to the - * mapping we cleared, we are in trouble. - */ - if (overlaps_kernel_text(aligned_start, addr) || - overlaps_kernel_text(end, aligned_end)) { - /* - * Hack, just return, don't pte_clear - */ - WARN_ONCE(1, "Linear mapping %lx->%lx overlaps kernel " - "text, not splitting\n", addr, end); - return; - } - split_region = true; - } - - if (split_region) { - params.pte = pte; - params.start = addr; - params.end = end; - params.aligned_start = addr & ~(size - 1); - params.aligned_end = min_t(unsigned long, aligned_end, - (unsigned long)__va(memblock_end_of_DRAM())); - stop_machine(stop_machine_change_mapping, ¶ms, NULL); - return; - } - - pte_clear(&init_mm, addr, pte); -} - static void remove_pmd_table(pmd_t *pmd_start, unsigned long addr, unsigned long end) { @@ -837,7 +764,12 @@ static void remove_pmd_table(pmd_t *pmd_start, unsigned long addr, continue; if (pmd_is_leaf(*pmd)) { - split_kernel_mapping(addr, end, PMD_SIZE, (pte_t *)pmd); + if (!IS_ALIGNED(addr, PMD_SIZE) || + !IS_ALIGNED(next, PMD_SIZE)) { + WARN_ONCE(1, "%s: unaligned range\n", __func__); + continue; + } + pte_clear(&init_mm, addr, (pte_t *)pmd); continue; } @@ -862,7 +794,12 @@ static void remove_pud_table(pud_t *pud_start, unsigned long addr, continue; if (pud_is_leaf(*pud)) { - split_kernel_mapping(addr, end, PUD_SIZE, (pte_t *)pud); + if (!IS_ALIGNED(addr, PUD_SIZE) || + !IS_ALIGNED(next, PUD_SIZE)) { + WARN_ONCE(1, "%s: unaligned range\n", __func__); + continue; + } + pte_clear(&init_mm, addr, (pte_t *)pud); continue; } @@ -890,7 +827,13 @@ static void __meminit remove_pagetable(unsigned long start, unsigned long end) continue; if (p4d_is_leaf(*p4d)) { - split_kernel_mapping(addr, end, P4D_SIZE, (pte_t *)p4d); + if (!IS_ALIGNED(addr, P4D_SIZE) || + !IS_ALIGNED(next, P4D_SIZE)) { + WARN_ONCE(1, "%s: unaligned range\n", __func__); + continue; + } + + pte_clear(&init_mm, addr, (pte_t *)pgd); continue; } -- 2.26.2