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Date:   Wed, 28 Jun 2023 18:45:54 +0200
From:   Michal Kubecek <mkubecek@suse.cz>
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: build failure after commit eb0481bbc4ce ("objtool: Fix
 reloc_hash size")
Message-ID: <20230628164554.womrvwq7chnjtva4@lion.mk-sys.cz>
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On Wed, Jun 28, 2023 at 06:06:31PM +0200, Michal Kubecek wrote:
> On Wed, Jun 28, 2023 at 05:44:32PM +0200, Michal Kubecek wrote:
> > On Wed, Jun 28, 2023 at 08:16:54AM -0700, Josh Poimboeuf wrote:
> > > Interesting.  Can you add the below patch and also do:
> > > 
> > >   make net/ipv4/netfilter/iptable_nat.o OBJTOOL_ARGS="--stats"
> > > 
> > > and report the output?
> > 
> > With these, I get
> > 
> >     ...
> >       CC [M]  net/ipv4/netfilter/iptable_nat.o
> >     nr_sections: 40
> >     section_bits: 10
> >     nr_symbols: 41
> >     symbol_bits: 10
> >     mmap reloc: Invalid argument
> >     make[1]: Leaving directory '/srv/ram/kobj'
> 
> Not sure if it's of any use but I also tried to run it under strace and
> the failed mmap() call seems to be
> 
>   18761 mmap(NULL, 0, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 EINVAL (Invalid argument)
> 
> Perhaps the problem could be that elf->num_relocs may be zero?

I added a printf() and got

  size = -4991471925827290382 = 0xbababababababaf2

for the elf_alloc_hash() invocation resulting in failed mmap().

Michal