netdev - Re: [PATCH 01/31] mm: serialize access to min_free

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] [day] [month] [year] [list]

Message-ID: <19141.36258.926599.862333@notabene.brown>
Date:	Fri, 2 Oct 2009 15:20:34 +1000
From:	Neil Brown <neilb@...e.de>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Suresh Jayaraman <sjayaraman@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	netdev@...r.kernel.org, Miklos Szeredi <mszeredi@...e.cz>,
	Wouter Verhelst <w@...r.be>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	trond.myklebust@....uio.no
Subject: Re: [PATCH 01/31] mm: serialize access to min_free_kbytes

On Thursday October 1, rientjes@...gle.com wrote:
> On Thu, 1 Oct 2009, Suresh Jayaraman wrote:
> 
> > From: Peter Zijlstra <a.p.zijlstra@...llo.nl> 
> > 
> > There is a small race between the procfs caller and the memory hotplug caller
> > of setup_per_zone_wmarks(). Not a big deal, but the next patch will add yet
> > another caller. Time to close the gap.
> > 
> 
> By "next patch," you mean "mm: emegency pool" (patch 08/31)?

:-)  It is always safer to say "a subsequent patch", isn't it....

> 
> If so, can't you eliminate var_free_mutex entirely from that patch and 
> take min_free_lock in adjust_memalloc_reserve() instead?

adjust_memalloc_reserve does a test alloc/free cycle under a lock.
That cannot be done under a spin-lock, it must be a mutex.
So I don't think you can eliminate var_free_mutex.

Thanks,
NeilBrown

> 
>  [ __adjust_memalloc_reserve() would call __setup_per_zone_wmarks()
>    under lock instead, now. ]
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html