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Tue, 28 Jul 2020 17:28:23 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06SHCiVr081715; Tue, 28 Jul 2020 17:28:23 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3030.oracle.com with ESMTP id 32hu5ufj71-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 28 Jul 2020 17:28:22 +0000 Received: from abhmp0004.oracle.com (abhmp0004.oracle.com [141.146.116.10]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 06SHS9Nb024053; Tue, 28 Jul 2020 17:28:10 GMT Received: from [10.154.121.35] (/10.154.121.35) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 28 Jul 2020 10:28:09 -0700 Subject: Re: [RFC PATCH 0/5] madvise MADV_DOEXEC To: Kirill Tkhai , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org Cc: mhocko@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, arnd@arndb.de, ebiederm@xmission.com, keescook@chromium.org, gerg@linux-m68k.org, christian.brauner@ubuntu.com, peterz@infradead.org, esyr@redhat.com, jgg@ziepe.ca, christian@kellner.me, areber@redhat.com, cyphar@cyphar.com, steven.sistare@oracle.com References: <1595869887-23307-1-git-send-email-anthony.yznaga@oracle.com> <46891e3b-ca08-197d-935f-fa0a52a60051@virtuozzo.com> From: Anthony Yznaga Organization: Oracle Corporation Message-ID: Date: Tue, 28 Jul 2020 10:28:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <46891e3b-ca08-197d-935f-fa0a52a60051@virtuozzo.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9696 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 mlxscore=0 adultscore=0 spamscore=0 phishscore=0 mlxlogscore=999 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007280127 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9696 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 clxscore=1015 mlxlogscore=999 malwarescore=0 impostorscore=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007280127 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/28/20 4:34 AM, Kirill Tkhai wrote: > On 27.07.2020 20:11, Anthony Yznaga wrote: >> This patchset adds support for preserving an anonymous memory range across >> exec(3) using a new madvise MADV_DOEXEC argument. The primary benefit for >> sharing memory in this manner, as opposed to re-attaching to a named shared >> memory segment, is to ensure it is mapped at the same virtual address in >> the new process as it was in the old one. An intended use for this is to >> preserve guest memory for guests using vfio while qemu exec's an updated >> version of itself. By ensuring the memory is preserved at a fixed address, > So, the goal is an update of QEMU binary without a stopping of virtual machine? Essentially, yes.  The VM is paused very briefly. Anthony > >> vfio mappings and their associated kernel data structures can remain valid. >> In addition, for the qemu use case, qemu instances that back guest RAM with >> anonymous memory can be updated. >> >> Patches 1 and 2 ensure that loading of ELF load segments does not silently >> clobber existing VMAS, and remove assumptions that the stack is the only >> VMA in the mm when the stack is set up. Patch 1 re-introduces the use of >> MAP_FIXED_NOREPLACE to load ELF binaries that addresses the previous issues >> and could be considered on its own. >> >> Patches 3, 4, and 5 introduce the feature and an opt-in method for its use >> using an ELF note. >> >> Anthony Yznaga (5): >> elf: reintroduce using MAP_FIXED_NOREPLACE for elf executable mappings >> mm: do not assume only the stack vma exists in setup_arg_pages() >> mm: introduce VM_EXEC_KEEP >> exec, elf: require opt-in for accepting preserved mem >> mm: introduce MADV_DOEXEC >> >> arch/x86/Kconfig | 1 + >> fs/binfmt_elf.c | 196 +++++++++++++++++++++++++-------- >> fs/exec.c | 33 +++++- >> include/linux/binfmts.h | 7 +- >> include/linux/mm.h | 5 + >> include/uapi/asm-generic/mman-common.h | 3 + >> kernel/fork.c | 2 +- >> mm/madvise.c | 25 +++++ >> mm/mmap.c | 47 ++++++++ >> 9 files changed, 266 insertions(+), 53 deletions(-) >>