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Date:   Wed, 6 Jul 2022 19:21:29 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     Christoph Hellwig <hch@infradead.org>, davem@davemloft.net,
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        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH bpf-next 0/5] bpf: BPF specific memory allocator.
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On Wed, Jul 06, 2022 at 11:05:25AM -0700, Alexei Starovoitov wrote:
> On Wed, Jul 06, 2022 at 06:55:36PM +0100, Matthew Wilcox wrote:
> > For example, I assume that a BPF program
> > has a fairly tight limit on how much memory it can cause to be allocated.
> > Right?
> 
> No. It's constrained by memcg limits only. It can allocate gigabytes.

I'm confused.  A BPF program is limited to executing 4096 insns and
using a maximum of 512 bytes of stack space, but it can allocate an
unlimited amount of heap?  That seems wrong.