Subject: Re: [PATCH RESEND v2 4/6] mm/page_alloc: sort out the alloc_contig_range() gfp flags mess

From: Oscar Salvador <[email-masked]>
Date: Wed, 4 Dec 2024 09:59:55 +0100

On Tue, Dec 03, 2024 at 08:19:02PM +0100, David Hildenbrand wrote:
> It was always set using "GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL",
> and I removed the same flag combination in #2 from memory offline code, and
> we do have the exact same thing in do_migrate_range() in
> mm/memory_hotplug.c.
> 
> We should investigate if__GFP_HARDWALL is the right thing to use here, and
> if we can get rid of that by switching to GFP_KERNEL in all these places.

Why would not we want __GFP_HARDWALL set?
Without it, we could potentially migrate the page to a node which is not
part of the cpuset of the task that originally allocated it, thus violating the
policy? Is not that a problem?

-- 
Oscar Salvador
SUSE Labs