linux-kernel - Re: [PATCH] perf: map pages in advance

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <8376a446-1e8d-4359-ac69-626790ebcd97@redhat.com>
Date: Fri, 29 Nov 2024 14:11:16 +0100
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>,
 Kan Liang <kan.liang@...ux.intel.com>, linux-perf-users@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH] perf: map pages in advance

On 29.11.24 13:48, Lorenzo Stoakes wrote:
> Will reply inline also but to be clear - we should differentiate between
> ongoing discussion about how best to tackle these things going forward
> vs. whether _this patch_ is OK :)
> 
> I don't think you're objecting to the patch as such, just disappointed
> about VM_PFNMAP and wanting to discuss this more generally?

Well, a bit of both :)

> 
> As I say below, we can't use VM_MIXEDMAP as it's broken for our case (we
> have to use page->mapping if there's a struct page), so I think _right now_
> this is the only sane solution.

I'm not so sure ...

I've also been wondering whether this particular user really wants to 
allocate and work on folios for the time being :/


Putting aside the remainder of what we discuss further below for now, 
I've just been wondering if we could somehow have two mappings with two 
separate ops. The one for the single R/W page, the other for the R/O 
pages ...

... but I'm not sure yet if that would completely help.

... still trying to grasp all the details here, and how to keep GUP working.

-- 
Cheers,

David / dhildenb