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mm, oom: consider present pages for the node size

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constrained_alloc() calculates the size of the oom domain by using
node_spanned_pages which is incorrect because this is the full range of
the physical memory range that the numa node occupies rather than the
memory that backs that range which is represented by node_present_pages.

Sparsely populated nodes (e.g.  after memory hot remove or simply sparse
due to memory layout) can have really a large difference between the two.
This shouldn't really cause any real user observable problems because the
oom calculates a ratio against totalpages and used memory cannot exceed
present pages but it is confusing and wrong from code point of view.

Link: http://lkml.kernel.org/r/20190829163443.899-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2019-09-23 15:37:16 -07:00 committed by Linus Torvalds
parent f364f06b34
commit 1eb41bb07e
1 changed files with 2 additions and 2 deletions
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4
mm/oom_kill.c
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@ -287,7 +287,7 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc)
!nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
oc->totalpages = total_swap_pages;
for_each_node_mask(nid, *oc->nodemask)
oc->totalpages += node_spanned_pages(nid);
oc->totalpages += node_present_pages(nid);
return CONSTRAINT_MEMORY_POLICY;
}
@ -300,7 +300,7 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc)
if (cpuset_limited) {
oc->totalpages = total_swap_pages;
for_each_node_mask(nid, cpuset_current_mems_allowed)
oc->totalpages += node_spanned_pages(nid);
oc->totalpages += node_present_pages(nid);
return CONSTRAINT_CPUSET;
}
return CONSTRAINT_NONE;