From: Dave Hansen <dave.hansen@linux.intel.com>
To: Rob Gardner <rob.gardner@oracle.com>,
Khalid Aziz <khalid.aziz@oracle.com>,
davem@davemloft.net, corbet@lwn.net, arnd@arndb.de,
akpm@linux-foundation.org
Cc: hpa@zytor.com, viro@zeniv.linux.org.uk, nitin.m.gupta@oracle.com,
chris.hyser@oracle.com, tushar.n.dave@oracle.com,
sowmini.varadhan@oracle.com, mike.kravetz@oracle.com,
adam.buchbinder@gmail.com, minchan@kernel.org, hughd@google.com,
kirill.shutemov@linux.intel.com, keescook@chromium.org,
allen.pais@oracle.com, aryabinin@virtuozzo.com,
atish.patra@oracle.com, joe@perches.com, pmladek@suse.com,
jslaby@suse.cz, cmetcalf@mellanox.com,
paul.gortmaker@windriver.com, mhocko@suse.com,
jmarchan@redhat.com, lstoakes@gmail.com, 0x7f454c46@gmail.com,
vbabka@suse.cz, tglx@linutronix.de, mingo@redhat.com,
dan.j.williams@intel.com, iamjoonsoo.kim@lge.com,
mgorman@techsingularity.net, vdavydov.dev@gmail.com,
hannes@cmpxchg.org, namit@vmware.com, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
linux-arch@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org,
Khalid Aziz <khalid@gonehiking.org>
Subject: Re: [RFC PATCH v3] sparc64: Add support for Application Data Integrity (ADI)
Date: Wed, 4 Jan 2017 15:49:43 -0800 [thread overview]
Message-ID: <2c0502d0-20ef-44ac-db5b-7f651a70b978@linux.intel.com> (raw)
In-Reply-To: <8612e7db-97c5-f757-0aae-24c3acedbc29@oracle.com>
On 01/04/2017 03:44 PM, Rob Gardner wrote:
> On 01/04/2017 03:40 PM, Dave Hansen wrote:
>> On 01/04/2017 03:35 PM, Rob Gardner wrote:
>>> Tags are not cleared at all when memory is freed, but rather, lazily
>>> (and automatically) cleared when memory is allocated.
>> What does "allocated" mean in this context? Physical or virtual? What
>> does this do, for instance?
>
> The first time a virtual page is touched by a process after the malloc,
> the kernel does clear_user_page() or something similar, which zeroes the
> memory. At the same time, the memory tags are cleared.
OK, so the tags can't survive a MADV_FREE. That's definitely something
for apps to understand that use MADV_FREE as a substitute for memset().
It also means that tags can't be set for physically unallocated memory.
Neither of those are deal killers, but it would be nice to document it.
How does this all work with large pages?
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next prev parent reply other threads:[~2017-01-04 23:49 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-04 22:46 [RFC PATCH v3] sparc64: Add support for Application Data Integrity (ADI) Khalid Aziz
2017-01-04 23:27 ` Dave Hansen
2017-01-04 23:35 ` Rob Gardner
2017-01-04 23:40 ` Dave Hansen
2017-01-04 23:44 ` Rob Gardner
2017-01-04 23:49 ` Dave Hansen [this message]
2017-01-04 23:56 ` Rob Gardner
2017-01-04 23:58 ` Khalid Aziz
2017-01-05 0:01 ` Dave Hansen
2017-01-05 0:05 ` Rob Gardner
2017-01-05 0:14 ` Dave Hansen
2017-01-05 0:26 ` Khalid Aziz
2017-01-05 19:22 ` Dave Hansen
2017-01-05 20:30 ` Khalid Aziz
2017-01-06 9:19 ` Michal Hocko
2017-01-06 15:32 ` Khalid Aziz
2017-01-06 15:36 ` Dave Hansen
2017-01-06 16:22 ` Khalid Aziz
2017-01-06 16:25 ` David Miller
2017-01-06 16:55 ` Dave Hansen
2017-01-06 17:02 ` David Miller
2017-01-06 17:10 ` Khalid Aziz
2017-01-06 17:54 ` Rob Gardner
2017-01-06 18:18 ` Khalid Aziz
2017-01-06 18:28 ` Rob Gardner
2017-01-06 17:08 ` Khalid Aziz
2017-01-04 23:43 ` Khalid Aziz
2017-01-04 23:31 ` Dave Hansen
2017-01-04 23:46 ` Khalid Aziz
2017-01-04 23:50 ` Dave Hansen
2017-01-05 9:37 ` Jerome Marchand
2017-01-05 15:13 ` Khalid Aziz
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