linux-kernel - Re: [linux-pm] [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: Memory allocations in .suspend became very unreliable)

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: <Pine.LNX.4.44L0.1001181116340.6554-100000@netrider.rowland.org>
Date:	Mon, 18 Jan 2010 11:17:57 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Oliver Neukum <oliver@...kum.org>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	<linux-pm@...ts.linux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [linux-pm] [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume
 (was: Re: Memory allocations in .suspend became very unreliable)

On Mon, 18 Jan 2010, Oliver Neukum wrote:

> Am Montag, 18. Januar 2010 00:00:23 schrieb Rafael J. Wysocki:
> > On Sunday 17 January 2010, Benjamin Herrenschmidt wrote:
> > > On Sun, 2010-01-17 at 14:27 +0100, Rafael J. Wysocki wrote:
> > ...
> > > However, it's hard to deal with the case of allocations that have
> > > already started waiting for IOs. It might be possible to have some VM
> > > hook to make them wakeup, re-evaluate the situation and get out of that
> > > code path but in any case it would be tricky.
> > 
> > In the second version of the patch I used an rwsem that made us wait for these
> > allocations to complete before we changed gfp_allowed_mask.
> 
> This will be a very, very hot semaphore. What's the impact on performance?

Can it be replaced with something having lower overhead, such as SRCU?

Alan Stern

--
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/