On 12/4/24 09:59, Oscar Salvador wrote: > 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? The task doing the alloc_contig_range() will likely not be the same task as the one that originally allocated the page, so its policy would be different, no? So even with __GFP_HARDWALL we might be already migrating outside the original tasks's constraint? Am I missing something?
