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=-5.2 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 08E87C433DB for ; Tue, 2 Feb 2021 14:42:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 700BE64F4D for ; Tue, 2 Feb 2021 14:42:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 700BE64F4D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C23B26B0073; Tue, 2 Feb 2021 09:42:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BD1976B007B; Tue, 2 Feb 2021 09:42:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A735C6B007D; Tue, 2 Feb 2021 09:42:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0250.hostedemail.com [216.40.44.250]) by kanga.kvack.org (Postfix) with ESMTP id 935F06B0073 for ; Tue, 2 Feb 2021 09:42:55 -0500 (EST) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5E9243633 for ; Tue, 2 Feb 2021 14:42:55 +0000 (UTC) X-FDA: 77773594710.09.cap09_440617c275cb Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin09.hostedemail.com (Postfix) with ESMTP id 40A77180AD806 for ; Tue, 2 Feb 2021 14:42:55 +0000 (UTC) X-HE-Tag: cap09_440617c275cb X-Filterd-Recvd-Size: 5808 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Feb 2021 14:42:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612276974; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=p9WVcjtJGSRM6w7F2m39UE8iZCliMcHMPGNuV986qrI=; b=OQo3i10NkK88wXMNXEXmca0BBgYvMgB4aFbJSf0m52DHmfo1XJm2rYtfET6sk+Vc4FE8bC dw8U/PVY0/csMZsHyU3g1o+hhwBOxQAAIT51769OIMxg5xCAw2KRFVBDHOP0s+PC4M6iUr 65LJvmG5s0DHRvV5gms9g+KHUTiST+0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-521-8AQi4yF_NHCuVEWiuakmOQ-1; Tue, 02 Feb 2021 09:42:42 -0500 X-MC-Unique: 8AQi4yF_NHCuVEWiuakmOQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 46BB9184DBED; Tue, 2 Feb 2021 14:42:36 +0000 (UTC) Received: from [10.36.114.148] (ovpn-114-148.ams2.redhat.com [10.36.114.148]) by smtp.corp.redhat.com (Postfix) with ESMTP id 36D6560916; Tue, 2 Feb 2021 14:42:28 +0000 (UTC) To: Michal Hocko , Mike Rapoport Cc: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer , Palmer Dabbelt References: <20210121122723.3446-1-rppt@kernel.org> <20210121122723.3446-8-rppt@kernel.org> <20210126114657.GL827@dhcp22.suse.cz> <303f348d-e494-e386-d1f5-14505b5da254@redhat.com> <20210126120823.GM827@dhcp22.suse.cz> <20210128092259.GB242749@kernel.org> <20210129072128.GD242749@kernel.org> From: David Hildenbrand Organization: Red Hat GmbH Subject: Re: [PATCH v16 07/11] secretmem: use PMD-size pages to amortize direct map fragmentation Message-ID: Date: Tue, 2 Feb 2021 15:42:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Content-Transfer-Encoding: quoted-printable 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 29.01.21 09:51, Michal Hocko wrote: > On Fri 29-01-21 09:21:28, Mike Rapoport wrote: >> On Thu, Jan 28, 2021 at 02:01:06PM +0100, Michal Hocko wrote: >>> On Thu 28-01-21 11:22:59, Mike Rapoport wrote: >>> >>>> And hugetlb pools may be also depleted by anybody by calling >>>> mmap(MAP_HUGETLB) and there is no any limiting knob for this, while >>>> secretmem has RLIMIT_MEMLOCK. >>> >>> Yes it can fail. But it would fail at the mmap time when the reservat= ion >>> fails. Not during the #PF time which can be at any time. >> >> It may fail at $PF time as well: >> >> hugetlb_fault() >> hugeltb_no_page() >> ... >> alloc_huge_page() >> alloc_gigantic_page() >> cma_alloc() >> -ENOMEM; >=20 > I would have to double check. From what I remember cma allocator is an > optimization to increase chances to allocate hugetlb pages when > overcommiting because pages should be normally pre-allocated in the poo= l > and reserved during mmap time. But even if a hugetlb page is not pre > allocated then this will get propagated as SIGBUS unless that has > changed. It's an optimization to allocate gigantic pages dynamically later (so=20 not using memblock during boot). Not just for overcommit, but for any=20 kind of allocation. The actual allocation from cma should happen when setting nr_pages: nr_hugepages_store_common()->set_max_huge_pages()->alloc_pool_huge_page()= ...->alloc_gigantic_page() The path described above seems to be trying to overcommit gigantic=20 pages, something that can be expected to SIGBUS. Reservations are=20 handled via the pre-allocated pool. --=20 Thanks, David / dhildenb