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SubjectRe: [PATCH] mm: don't warn if the node is offlined
On Tue 01-11-22 12:13:35, Zach O'Keefe wrote:
[...]
> This is slightly tangential - but I don't want to send a new mail
> about it -- but I wonder if we should be doing __GFP_THISNODE +
> explicit node vs having hpage_collapse_find_target_node() set a
> nodemask. We could then provide fallback nodes for ties, or if some
> node contained > some threshold number of pages.

I would simply go with something like this (not even compile tested):

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4734315f7940..947a5158fe11 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -96,9 +96,6 @@ struct collapse_control {

/* Num pages scanned per node */
u32 node_load[MAX_NUMNODES];
-
- /* Last target selected in hpage_collapse_find_target_node() */
- int last_target_node;
};

/**
@@ -734,7 +731,6 @@ static void khugepaged_alloc_sleep(void)

struct collapse_control khugepaged_collapse_control = {
.is_khugepaged = true,
- .last_target_node = NUMA_NO_NODE,
};

static bool hpage_collapse_scan_abort(int nid, struct collapse_control *cc)
@@ -772,7 +768,7 @@ static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void)
}

#ifdef CONFIG_NUMA
-static int hpage_collapse_find_target_node(struct collapse_control *cc)
+static int hpage_collapse_find_target_node(struct collapse_control *cc, nodemask_t *alloc_mask)
{
int nid, target_node = 0, max_value = 0;

@@ -783,28 +779,25 @@ static int hpage_collapse_find_target_node(struct collapse_control *cc)
target_node = nid;
}

+ nodes_clear(&alloc_mask);
/* do some balance if several nodes have the same hit record */
- if (target_node <= cc->last_target_node)
- for (nid = cc->last_target_node + 1; nid < MAX_NUMNODES;
- nid++)
- if (max_value == cc->node_load[nid]) {
- target_node = nid;
- break;
- }
+ for_each_online_node(nid) {_
+ if (max_value == cc->node_load[nid])
+ node_set(nid, &alloc_mask)
+ }

- cc->last_target_node = target_node;
return target_node;
}
#else
-static int hpage_collapse_find_target_node(struct collapse_control *cc)
+static int hpage_collapse_find_target_node(struct collapse_control *cc, nodemask_t *alloc_mask)
{
return 0;
}
#endif

-static bool hpage_collapse_alloc_page(struct page **hpage, gfp_t gfp, int node)
+static bool hpage_collapse_alloc_page(struct page **hpage, gfp_t gfp, int node, nodemask_t *nmask)
{
- *hpage = __alloc_pages_node(node, gfp, HPAGE_PMD_ORDER);
+ *hpage = __alloc_pages(gfp, HPAGE_PMD_ORDER, node, nmask);
if (unlikely(!*hpage)) {
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
return false;
@@ -958,9 +951,18 @@ static int alloc_charge_hpage(struct page **hpage, struct mm_struct *mm,
/* Only allocate from the target node */
gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
GFP_TRANSHUGE) | __GFP_THISNODE;
- int node = hpage_collapse_find_target_node(cc);
+ NODEMASK_ALLOC(nodemask_t, nmask, GFP_KERNEL);
+ int node;
+ int ret;
+
+ if (!nmaks)
+ return SCAN_ALLOC_HUGE_PAGE_FAIL;
+
+ node = hpage_collapse_find_target_node(cc, nmask);
+ ret = hpage_collapse_alloc_page(hpage, gfp, node, nmask);
+ NODEMASK_FREE(nmask);

- if (!hpage_collapse_alloc_page(hpage, gfp, node))
+ if (!ret)
return SCAN_ALLOC_HUGE_PAGE_FAIL;
if (unlikely(mem_cgroup_charge(page_folio(*hpage), mm, gfp)))
return SCAN_CGROUP_CHARGE_FAIL;
@@ -2576,7 +2578,6 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
if (!cc)
return -ENOMEM;
cc->is_khugepaged = false;
- cc->last_target_node = NUMA_NO_NODE;

mmgrab(mm);
lru_add_drain_all();
--
Michal Hocko
SUSE Labs
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