From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752641AbdBMOlJ (ORCPT ); Mon, 13 Feb 2017 09:41:09 -0500 Received: from mail-ve1eur01on0137.outbound.protection.outlook.com ([104.47.1.137]:10368 "EHLO EUR01-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752172AbdBMOlG (ORCPT ); Mon, 13 Feb 2017 09:41:06 -0500 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=dsafonov@virtuozzo.com; Subject: Re: [PATCHv4 2/5] x86/mm: introduce mmap{,_legacy}_base To: Thomas Gleixner References: <20170130120432.6716-1-dsafonov@virtuozzo.com> <20170130120432.6716-3-dsafonov@virtuozzo.com> CC: , <0x7f454c46@gmail.com>, Ingo Molnar , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov , , From: Dmitry Safonov Message-ID: Date: Mon, 13 Feb 2017 17:37:09 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [195.214.232.6] X-ClientProxiedBy: AM4PR0701CA0032.eurprd07.prod.outlook.com (10.165.102.42) To DB6PR0801MB1735.eurprd08.prod.outlook.com (10.169.226.150) X-MS-Office365-Filtering-Correlation-Id: 62eb97a9-9def-458f-34a8-08d4541e5026 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001);SRVR:DB6PR0801MB1735; X-Microsoft-Exchange-Diagnostics: 1;DB6PR0801MB1735;3:3sFaa8sVzwq/aUg6Hn/PfgSxrTUe9k6cYAV8fDN9OZfG2ZwvRVVmmW5Vn1Ol058f5tdpDEH9GKBLuBwyDmvCpk+H2pk4alq9TeyIz4a5bZ8OjMgTdlBGul9PJnXeugkCmytPmES4CyCypPvlX3xSTdqL96GrSwmJO9KOB62a5TCu4PHP7DQxtR4yLFQ0qWnL4+vN/B/MSkcnle1Ju7jpXBtjeH5Ic/m/fVaMM/HB/FZSnH5Qggg1/whm+Rmc7Lrdcjxokie/95GwPrLFjs4NkA==;25:pawVL2yij4YwxPGqpjig6mQbinsdBL3eVouy03O8Ru7c1IdM0LDiEltgPlZ8W0ivcoOX0JPrkIBu/irFw0bOhDxtwM0+4JgV/DkybTUvu0e2GZqGz3S/p+vro6v416WvVx+DKdtpAEKUOd319sHoemAkA2NJpQIv0PkTRWZ+gnItyn7qdMO9Svvnl64bz1GyxWQPXUc1723oGG4QhoPVwu4X8FDG8HpnPnM76Uu4dST51CKSaGli+wNoSuJHCIRa3MtVAJ079Sr5tSHxMwUR1xuDQiAg0i0cwSpoVodrh5isDpqcSbgvbn0vzVgzeaCe20jVtVevoC1z9a96tdp0Wr9p2/w+DnzCDtQoYm5SpmlywtGqsdAYCNGTTV8GCafJK12WKQ5aglA4NenA+kjIEd/PRhtL8LNsk7niDGceQJR+b4aWGenmgmfENR8CN85SR8VY3u7mUeIQFBypwOySoQ== X-Microsoft-Exchange-Diagnostics: 1;DB6PR0801MB1735;31:O7W6cIJueLmFU0nNrxHVRqooz2p//F5rXVD4NZpRDTgmIvzvPxL1wdyIxUX5GT0Lk04PsOtpsj4CX9GLvwQWe+nb8SyhQbLAXX1GmicH99F8ZlZaaKSyShuVczSxQI1gTX1p8mK8GE2S7b98W2iGVRo3+DM4M8cPh3lKJwTGUGvOgLUyOw9vXRKbMqOcNPltZlnSfQFEO6rGpYQGqRhLDxojGFakBkj7+hdJr2zdtaaweTD1rMZXnD8xapz1S9mN;20:eb/KxF4p1nI67/nksGFth7GcyLJ2RfqUAQF9Howk7xizS2A1YnL2LrYB+GIfafGdbMnLGgDGmx2t5WIbQO5gf0dsm6nNdtZXOANk13kd9njHPZPF7HQJZ7GNNFGmj8K0B340iq0mTlzo2SUQ0qzLwJ46jKK+/T9R5WR0pxfWIcQbcUO9sFPZ2DaBRY7ANWXaXX3cmFYxbU3t03fD2BqDCH0gtEhTArtBImRIOYQytK37N8HeSUCveTmXk0LFcCva9X7JRNjtOcnDmnvhpecEI+0RA+ZEgiXwRi958qPSbfFAKp3qmQbFh0q6Poe50pocwxjVFq8QG6qA+BMDi/RwF30MoOzM95i7PdHwBTF7CRZa0U0Coz/1Uod9skO9/LWB8+ixponAwFFCMMA9ooq4QSUhfMbsoNCCmpENCNQEhIU= X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; 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> unsigned long gap_min, gap_max; > > /* Add comment what this means */ > gap_min = SIZE_128M + stack_maxrandom_size(task_size); > /* Explain that ' /6 * 5' magic */ > gap_max = (task_size / 6) * 5; So, I can't find about those limits on a gap size: They were introduced by commit 8913d55b6c58 ("i386 virtual memory layout rework"). All I could find is that 128Mb limit was more limit on virtual adress space than on a memory available those days. And 5/6 of task_size looks like heuristic value. So I'm not sure, what to write in comments: that rlimit on stack can't be bigger than 5/6 of task_size? That looks obvious from the code. -- Dmitry