Re: [PATCH 04/17] arm: get rid of superfluous __GFP_REPEAT
From: Russell King - ARM Linux
Date: Wed Jun 01 2016 - 12:24:47 EST
On Mon, May 30, 2016 at 11:14:46AM +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
> __GFP_REPEAT has a rather weak semantic but since it has been introduced
> around 2.6.12 it has been ignored for low order allocations.
> PGALLOC_GFP uses __GFP_REPEAT but none of the allocation which uses
> this flag is for more than order-2. This means that this flag has never
> been actually useful here because it has always been used only for
> PAGE_ALLOC_COSTLY requests.
I hear what you say, but...
Author: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Date: Sat Nov 30 12:52:31 2013 +0000
ARM: pgd allocation: retry on failure
Make pgd allocation retry on failure; we really need this to succeed
otherwise fork() can trigger OOMs.
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
and that's the change which introduced this, and it did solve a problem
for me. So I'm not happy to give an ack for this change unless someone
can tell me why adding __GFP_REPEAT back then had a beneficial effect.
Maybe there was some other bug in the MM layer in 2013 which this change
happened to solve?
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.