On Fri, 23 Jun 2017 10:53:45 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> From: Michal Hocko <mhocko@xxxxxxxx>
>
> Page migration (for memory hotplug, soft_offline_page or mbind) needs
> to allocate a new memory. This can trigger an oom killer if the target
> memory is depleated. Although quite unlikely, still possible, especially
> for the memory hotplug (offlining of memoery). Up to now we didn't
> really have reasonable means to back off. __GFP_NORETRY can fail just
> too easily and __GFP_THISNODE sticks to a single node and that is not
> suitable for all callers.
>
> But now that we have __GFP_RETRY_MAYFAIL we should use it. It is
> preferable to fail the migration than disrupt the system by killing some
> processes.
I'm not sure which tree this is against...
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1492,7 +1492,8 @@ static struct page *new_page(struct page *p, unsigned long private, int **x)
>
> return alloc_huge_page_node(hstate, nid);
> } else {
> - return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0);
> + return __alloc_pages_node(nid,
> + GFP_HIGHUSER_MOVABLE | __GFP_RETRY_MAYFAIL, 0);
> }
> }
new_page() is now
static struct page *new_page(struct page *p, unsigned long private, int **x)
{
int nid = page_to_nid(p);
return new_page_nodemask(p, nid, &node_states[N_MEMORY]);
}
and new_page_nodemask() uses __GFP_RETRY_MAYFAIL so I simply dropped
the above hunk.
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