From: Shakeel Butt <shakeel.butt@linux.dev>
To: David Hildenbrand <david@redhat.com>
Cc: Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
martin.lau@kernel.org, linux-mm@kvack.org,
linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Yi Lai <yi1.lai@intel.com>,
pbonzini@redhat.com, seanjc@google.com, tabba@google.com,
jackmanb@google.com, yosryahmed@google.com, jannh@google.com,
rppt@kernel.org
Subject: Re: [PATCH bpf] lib/buildid: handle memfd_secret() files in build_id_parse()
Date: Thu, 17 Oct 2024 09:22:36 -0700 [thread overview]
Message-ID: <d62whv7kff5yshsyzkykgxpgfycfivygyhlqwifvudnj5adun7@kqd6hcsbmee6> (raw)
In-Reply-To: <d62bd511-13ac-4030-a4f3-ff81025170c1@redhat.com>
On Thu, Oct 17, 2024 at 11:17:19AM GMT, David Hildenbrand wrote:
> On 16.10.24 20:39, Shakeel Butt wrote:
> > Ccing couple more folks who are doing similar work (ASI, guest_memfd)
> >
> > Folks, what is the generic way to check if a given mapping has folios
> > unmapped from kernel address space?
>
>
> Can't we just lookup the mapping and refuse these folios that really
> shouldn't be looked at?
>
> See gup_fast_folio_allowed() where we refuse secretmem_mapping().
That is exactly what this patch is doing. See [1]. The reason I asked
this question was because I see parallel efforts related to guest_memfd
and ASI are going to unmap folios from direct map. (Yosry already
explained ASI is a bit different). We want a more robust and future
proof solution.
[1] https://lore.kernel.org/all/20241014235631.1229438-1-andrii@kernel.org/
>
>
> --
> Cheers,
>
> David / dhildenb
>
next prev parent reply other threads:[~2024-10-17 16:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-14 23:56 Andrii Nakryiko
2024-10-15 0:00 ` Shakeel Butt
2024-10-16 18:39 ` Shakeel Butt
2024-10-16 19:59 ` Yosry Ahmed
2024-10-16 21:45 ` Shakeel Butt
2024-10-17 9:17 ` David Hildenbrand
2024-10-17 16:22 ` Shakeel Butt [this message]
2024-10-17 17:41 ` David Hildenbrand
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