linux-kernel - Re: [PATCH] mm: protect against concurrent vma expansion

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]

Date:	Wed, 19 Dec 2012 19:01:30 -0800
From:	Michel Lespinasse <walken@...gle.com>
To:	Simon Jeons <simon.jeons@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: protect against concurrent vma expansion

Hi Simon,

On Wed, Dec 19, 2012 at 5:56 PM, Simon Jeons <simon.jeons@...il.com> wrote:
> One question.
>
> I found that mainly callsite of expand_stack() is #PF, but it holds
> mmap_sem each time before call expand_stack(), how can hold a *shared*
> mmap_sem happen?

the #PF handler calls down_read(&mm->mmap_sem) before calling expand_stack.

I think I'm just confusing you with my terminology; shared lock ==
read lock == several readers might hold it at once (I'd say they share
it)

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/