linux-kernel - Re: Hang on large copy_from_user with PREEMPT

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Message-ID: <87bnj03dym.fsf@rustcorp.com.au>
Date:	Tue, 07 Apr 2015 11:19:05 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Sasha Levin <sasha.levin@...cle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Dave Jones <davej@...hat.com>,
	Michal Hocko <mhocko@...e.cz>, Borislav Petkov <bp@...en8.de>,
	"the arch\/x86 maintainers" <x86@...nel.org>
Subject: Re: Hang on large copy_from_user with PREEMPT_NONE

Linus Torvalds <torvalds@...ux-foundation.org> writes:
> Alternatively, we could just limit module loading size to some (fairly
> arbitrary) big number.

Yeah, we used to do that because vmalloc would BUG rather than
returning NULL.

But you're already CAP_SYS_MODULE in this path, which kind of makes it
hard to care very much about it being slow under virtualization.

Cheers,
Rusty.
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