From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x226BIyqy1lfTj6O4rKwpt9A4h/QtksOQKNkKws44kqqDXXzsh7L+zzJdawFrGgZa4dGdPtt4 ARC-Seal: i=1; a=rsa-sha256; t=1519721850; cv=none; d=google.com; s=arc-20160816; b=rTc7IPNCQXyKrrh6yinBJIeOPXxiYSvPvo5ryQnoMScdA+9ZfF7R1OpOygU1uyV/wF IAjuGVUO8at8oEqxzqXHKZzwVC2nBaEbd/L3xqI0aZspN2D3d8DtdgGoznS3MUk/ye0X +GTZz20xMQYk+ALoGuL675VQfUAZD5rCOsXiSuBiddZYb4LzhqC4JomLVn8BDMc6gsbW NcTiPWQ+sKVIGL5qJeCGYnUOLkpn/M7kX90ggSjYHVue3llNCtXGh7WG6CsXIBSMCoYu KQ5GAPvMSXH7usAi/KIwK/8ZdnfWJPqnviaKtdaePxalCWxldIV2wzH7PJL41oBWPvYq l6ZQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:arc-authentication-results; bh=2+/7LowXRF9jcurzYLnBsEzcKIvVGzAZHz7mV7zCWI0=; b=leBc6QLJH1zaXlN6OLHxnRNZKVtsjKpkv4Trlr/aItqFAwyHyEik5zSyel3p6KmCko lPyJi6q8wbcnXh0/Q1q/k3kmjXIgHmYU+ZeTBQCYA7sgjiWk2HveCEAY5TbOxJR0pkt+ vzMIwhB+ytT9/zFfOIyrzRSjO0Wc9DEs+1R92gsNu21abvKJCHMdQGzJOc1EcP223ynP 334vivdMm7tDf9WUSFqHYlg3FWeIncSS1mstUGVzBN4eW0NqXbtRfWylqyYpzIAslMUV OFhZnF17Jcumt5pyyORDhNh6ac46D1koSfKjIMice6dqZERaMm9F3OXE66/bhvqhV9n1 QNRA== ARC-Authentication-Results: i=1; mx.google.com; spf=neutral (google.com: 195.135.220.15 is neither permitted nor denied by best guess record for domain of mhocko@kernel.org) smtp.mailfrom=mhocko@kernel.org Authentication-Results: mx.google.com; spf=neutral (google.com: 195.135.220.15 is neither permitted nor denied by best guess record for domain of mhocko@kernel.org) smtp.mailfrom=mhocko@kernel.org Date: Tue, 27 Feb 2018 09:57:27 +0100 From: Michal Hocko To: Ilya Smith Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, kirill.shutemov@linux.intel.com, dsafonov@virtuozzo.com, hughd@google.com, gregkh@linuxfoundation.org, craigb@google.com, oleg@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] Take mmap_min_addr into account while choosing unmapped address for x86-64. Message-ID: <20180227085726.GC15357@dhcp22.suse.cz> References: <20180226211257.63067-1-blackzert@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180226211257.63067-1-blackzert@gmail.com> User-Agent: Mutt/1.9.3 (2018-01-21) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1593499619093217840?= X-GMAIL-MSGID: =?utf-8?q?1593543859366419546?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue 27-02-18 00:12:57, Ilya Smith wrote: [...] > diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c > index 676774b9bb8d..1752fe5cb735 100644 > --- a/arch/x86/kernel/sys_x86_64.c > +++ b/arch/x86/kernel/sys_x86_64.c > @@ -17,6 +17,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -185,7 +186,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, > return addr; > > /* requested length too big for entire address space */ > - if (len > TASK_SIZE) > + if (len > TASK_SIZE - mmap_min_addr) > return -ENOMEM; > > /* No address checking. See comment at mmap_address_hint_valid() */ > @@ -210,7 +211,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, > > info.flags = VM_UNMAPPED_AREA_TOPDOWN; > info.length = len; > - info.low_limit = PAGE_SIZE; > + info.low_limit = max(PAGE_SIZE, mmap_min_addr); > info.high_limit = get_mmap_base(0); > > /* mmap_min_addr handling is a bit mess... As you say, we would return EPERM rather than ENOMEM which can be confusing but depleting the address space like that is quite unlikely on 64b unless I am missing. It is good to be in sync here with the generic implementation though, IMO. > diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c > index 155ecbac9e28..b6d0c317639e 100644 > --- a/arch/x86/mm/mmap.c > +++ b/arch/x86/mm/mmap.c > @@ -31,6 +31,7 @@ > #include > #include > #include > +#include > #include > > #include "physaddr.h" > @@ -220,6 +221,9 @@ bool mmap_address_hint_valid(unsigned long addr, unsigned long len) > if (TASK_SIZE - len < addr) > return false; > > + if (addr < mmap_min_addr) > + return false; > + > return (addr > DEFAULT_MAP_WINDOW) == (addr + len > DEFAULT_MAP_WINDOW); But is this one necessary? We do sanitze hint address before going to get_unmapped_address AFAIR. -- Michal Hocko SUSE Labs