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From:   David Hildenbrand <david@redhat.com>
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Subject: Re: [PATCH RFC] mm/madvise: introduce MADV_POPULATE to prefault/prealloc memory
Date:   Thu, 18 Feb 2021 12:27:14 +0100
Message-Id: <254581A8-3108-436F-80AF-129B3F93CBF4@redhat.com>
References: <50f73055950ff7382f2194134ef0f439@sf-tec.de>
Cc:     Vlastimil Babka <vbabka@suse.cz>,
        David Hildenbrand <david@redhat.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>, Michal Hocko <mhocko@suse.com>,
        Oscar Salvador <osalvador@suse.de>,
        Matthew Wilcox <willy@infradead.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Minchan Kim <minchan@kernel.org>, Jann Horn <jannh@google.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Dave Hansen <dave.hansen@intel.com>,
        Hugh Dickins <hughd@google.com>,
        Rik van Riel <riel@surriel.com>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Richard Henderson <rth@twiddle.net>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
        Matt Turner <mattst88@gmail.com>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        "James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
        Helge Deller <deller@gmx.de>, Chris Zankel <chris@zankel.net>,
        Max Filippov <jcmvbkbc@gmail.com>, linux-alpha@vger.kernel.org,
        linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
        linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org,
        Linux API <linux-api@vger.kernel.org>
In-Reply-To: <50f73055950ff7382f2194134ef0f439@sf-tec.de>
To:     Rolf Eike Beer <eike-kernel@sf-tec.de>
Precedence: bulk


> Am 18.02.2021 um 12:15 schrieb Rolf Eike Beer <eike-kernel@sf-tec.de>:
>=20
> =EF=BB=BF
>>=20
>>> Let's introduce MADV_POPULATE with the following semantics
>>> 1. MADV_POPULATED does not work on PROT_NONE and special VMAs. It works
>>>   on everything else.
>>> 2. Errors during MADV_POPULATED (especially OOM) are reported. If we hit=

>>>   hardware errors on pages, ignore them - nothing we really can or
>>>   should do.
>>> 3. On errors during MADV_POPULATED, some memory might have been
>>>   populated. Callers have to clean up if they care.
>>> 4. Concurrent changes to the virtual memory layour are tolerated - we
>                                                    ^t
>>>   process each and every PFN only once, though.
>>> 5. If MADV_POPULATE succeeds, all memory in the range can be accessed
>>>   without SIGBUS. (of course, not if user space changed mappings in the
>>>   meantime or KSM kicked in on anonymous memory).
>=20
> You are talking both about MADV_POPULATE and MADV_POPULATED here.
>=20

Already fixed up :) thanks!

> Eike
>=20