linux-kernel - Re: [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.

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]

Message-Id: <201110171245.31256.dtor@vmware.com>
Date:	Mon, 17 Oct 2011 12:45:30 -0700
From:	Dmitry Torokhov <dtor@...are.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Rakib Mullick <rakib.mullick@...il.com>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] drivers, vmw_balloon.c: Increment alloc and sleep_alloc only when page allocation succeeds.

On Monday, October 17, 2011 12:35:34 PM David Rientjes wrote:
> On Tue, 18 Oct 2011, Rakib Mullick wrote:
> >  While doing allocation statistics in vmballoon_reserve_page function,
> > 
> > alloc and sleep_alloc has been incremented even if allocation fails.
> > But,
> > b->stats.alloc and b->stats.sleep_alloc supposed to increment only
> > when they succeed. This patch makes sure that, alloc and sleep_alloc
> > gets incremented when page allocation succeeds.
> 
> Dmitry could say for sure, but this seems to actually change the
> semantics.  If the allocations fail, it increments alloc_fail and
> sleep_alloc_fail accordingly so you could easily see 10 alloc and 5
> alloc_fail.  With your patch, it would be 5 alloc and 5 alloc_fail.
> 
> I don't know which one is best, but I would opt to stay with the
> semantics that alloc and sleep_alloc have already had rather than
> changing them.

Right, b->stats.alloc and b->stats.sleep_alloc show number of allocation
attempts and alloc_fail and sleep_alloc_fail show how many of these
attempts failed. This behavior matches behavior of the driver we have
been shipping out of the tree for many years and I would prefer to keep
it as is.

Thanks,
Dmitry

--
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/