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  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:	Sat, 19 May 2007 20:30:31 +0800
From:	Fengguang Wu <>
To:	Andrew Morton <>
Cc:, Andi Kleen <>,
	Jens Axboe <>,
	Oleg Nesterov <>,
	Steven Pratt <>,
	Ram Pai <>,
	"" <>
Subject: Re: [PATCH 1/9] readahead: introduce PG_readahead

On Fri, May 18, 2007 at 11:28:24PM -0700, Andrew Morton wrote:
> On Thu, 17 May 2007 06:47:53 +0800 Fengguang Wu <> wrote:
> > Introduce a new page flag: PG_readahead.
> Is there any way in which we can avoid adding a new page flag?
> We have the advantage that if the kernel very occasionally gets the wrong
> result for PageReadahead(page), nothing particularly bad will happen, so we
> can do racy things.
> >From a quick peek, it appears that PG_readahead is only ever set against
> non-uptodate pages.  If true we could perhaps exploit that: say,
> PageReadahead(page) == PG_referenced && !PG_uptodate?

PG_uptodate will flip to 1 before the reader touches the page :(

However, it may be possible to share the same bit with PG_reclaim or PG_booked.
Which one would be preferred?

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists