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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,URIBL_BLOCKED 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 95110C433B4 for ; Fri, 30 Apr 2021 05:57:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3AF2161480 for ; Fri, 30 Apr 2021 05:57:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3AF2161480 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BC7A88D0008; Fri, 30 Apr 2021 01:57:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B4FF68D0005; Fri, 30 Apr 2021 01:57:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A18188D0008; Fri, 30 Apr 2021 01:57:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0028.hostedemail.com [216.40.44.28]) by kanga.kvack.org (Postfix) with ESMTP id 80F618D0005 for ; Fri, 30 Apr 2021 01:57:21 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 4345F5923BFC for ; Fri, 30 Apr 2021 05:57:21 +0000 (UTC) X-FDA: 78087975882.15.5FB572F Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf11.hostedemail.com (Postfix) with ESMTP id 245172000273 for ; Fri, 30 Apr 2021 05:57:05 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id B3EC56147D; Fri, 30 Apr 2021 05:57:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762240; bh=qBh1IeiMt3wS1bEIDrzYYhBcge2fw3Anb0xBVwplAMQ=; h=Date:From:To:Subject:In-Reply-To:From; b=s+OtfxOPpJngA1FS4YVXWAPv4Egnvcg4kIe/zA4IL5dSQynkOpX/A9AnC1RPcpuy8 43ZgtwcyvRwFlJz5tYV8mdlBYUsqkTjIl9la+Klcr6/Nz5ZIc4QOcASeDLe0E0khXH Jv5mPb+c7NV2wZC5Xr9fCAT0YRcfj8wt6t4HBNMk= Date: Thu, 29 Apr 2021 22:57:19 -0700 From: Andrew Morton To: akpm@linux-foundation.org, bp@alien8.de, dave.hansen@linux.intel.com, david@redhat.com, hpa@zytor.com, linux-mm@kvack.org, luto@kernel.org, mhocko@kernel.org, mingo@redhat.com, mm-commits@vger.kernel.org, osalvador@suse.de, peterz@infradead.org, tglx@linutronix.de, torvalds@linux-foundation.org, ziy@nvidia.com Subject: [patch 081/178] x86/vmemmap: handle unpopulated sub-pmd ranges Message-ID: <20210430055719.GC7_cOkEn%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 245172000273 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=s+OtfxOP; dmarc=none; spf=pass (imf11.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Stat-Signature: 115uuozkwptozdak9sfsn1eofa7usynh Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1619762225-170012 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: From: Oscar Salvador Subject: x86/vmemmap: handle unpopulated sub-pmd ranges When sizeof(struct page) is not a power of 2, sections do not span a PMD anymore and so when populating them some parts of the PMD will remain unused. Because of this, PMDs will be left behind when depopulating sections since remove_pmd_table() thinks that those unused parts are still in use. Fix this by marking the unused parts with PAGE_UNUSED, so memchr_inv() will do the right thing and will let us free the PMD when the last user of it is gone. This patch is based on a similar patch by David Hildenbrand: https://lore.kernel.org/linux-mm/20200722094558.9828-9-david@redhat.com/ [osalvador@suse.de: go back to the ifdef version] Link: https://lkml.kernel.org/r/YGy++mSft7K4u+88@localhost.localdomain Link: https://lkml.kernel.org/r/20210309214050.4674-4-osalvador@suse.de Signed-off-by: Oscar Salvador Reviewed-by: David Hildenbrand Acked-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov Cc: "H . Peter Anvin" Cc: Ingo Molnar Cc: Michal Hocko Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Zi Yan Signed-off-by: Andrew Morton --- arch/x86/mm/init_64.c | 68 ++++++++++++++++++++++++++++++++-------- 1 file changed, 55 insertions(+), 13 deletions(-) --- a/arch/x86/mm/init_64.c~x86-vmemmap-handle-unpopulated-sub-pmd-ranges +++ a/arch/x86/mm/init_64.c @@ -826,6 +826,51 @@ void __init paging_init(void) zone_sizes_init(); } +#ifdef CONFIG_SPARSEMEM_VMEMMAP +#define PAGE_UNUSED 0xFD + +/* Returns true if the PMD is completely unused and thus it can be freed */ +static bool __meminit vmemmap_pmd_is_unused(unsigned long addr, unsigned long end) +{ + unsigned long start = ALIGN_DOWN(addr, PMD_SIZE); + + memset((void *)addr, PAGE_UNUSED, end - addr); + + return !memchr_inv((void *)start, PAGE_UNUSED, PMD_SIZE); +} + +static void __meminit vmemmap_use_sub_pmd(unsigned long start) +{ + /* + * As we expect to add in the same granularity as we remove, it's + * sufficient to mark only some piece used to block the memmap page from + * getting removed when removing some other adjacent memmap (just in + * case the first memmap never gets initialized e.g., because the memory + * block never gets onlined). + */ + memset((void *)start, 0, sizeof(struct page)); +} + +static void __meminit vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end) +{ + /* + * Could be our memmap page is filled with PAGE_UNUSED already from a + * previous remove. Make sure to reset it. + */ + vmemmap_use_sub_pmd(start); + + /* + * Mark with PAGE_UNUSED the unused parts of the new memmap range + */ + if (!IS_ALIGNED(start, PMD_SIZE)) + memset((void *)start, PAGE_UNUSED, + start - ALIGN_DOWN(start, PMD_SIZE)); + if (!IS_ALIGNED(end, PMD_SIZE)) + memset((void *)end, PAGE_UNUSED, + ALIGN(end, PMD_SIZE) - end); +} +#endif + /* * Memory hotplug specific functions */ @@ -871,8 +916,6 @@ int arch_add_memory(int nid, u64 start, return add_pages(nid, start_pfn, nr_pages, params); } -#define PAGE_INUSE 0xFD - static void __meminit free_pagetable(struct page *page, int order) { unsigned long magic; @@ -1006,7 +1049,6 @@ remove_pmd_table(pmd_t *pmd_start, unsig unsigned long next, pages = 0; pte_t *pte_base; pmd_t *pmd; - void *page_addr; pmd = pmd_start + pmd_index(addr); for (; addr < end; addr = next, pmd++) { @@ -1026,22 +1068,16 @@ remove_pmd_table(pmd_t *pmd_start, unsig pmd_clear(pmd); spin_unlock(&init_mm.page_table_lock); pages++; - } else { - /* If here, we are freeing vmemmap pages. */ - memset((void *)addr, PAGE_INUSE, next - addr); - - page_addr = page_address(pmd_page(*pmd)); - if (!memchr_inv(page_addr, PAGE_INUSE, - PMD_SIZE)) { + } +#ifdef CONFIG_SPARSEMEM_VMEMMAP + else if (vmemmap_pmd_is_unused(addr, next)) { free_hugepage_table(pmd_page(*pmd), altmap); - spin_lock(&init_mm.page_table_lock); pmd_clear(pmd); spin_unlock(&init_mm.page_table_lock); - } } - +#endif continue; } @@ -1492,11 +1528,17 @@ static int __meminit vmemmap_populate_hu addr_end = addr + PMD_SIZE; p_end = p + PMD_SIZE; + + if (!IS_ALIGNED(addr, PMD_SIZE) || + !IS_ALIGNED(next, PMD_SIZE)) + vmemmap_use_new_sub_pmd(addr, next); + continue; } else if (altmap) return -ENOMEM; /* no fallback */ } else if (pmd_large(*pmd)) { vmemmap_verify((pte_t *)pmd, node, addr, next); + vmemmap_use_sub_pmd(addr); continue; } if (vmemmap_populate_basepages(addr, next, node, NULL)) _