Re: [PATCH v3] mm: fix panic in __alloc_pages

Michal Hocko
2021-12-21T09:46:46Z

On Tue 21-12-21 05:46:16, Alexey Makhalov wrote:
> Hi Michal,
>
> The patchset looks good to me. I didn’t find any issues during the testing.

Thanks a lot. Can I add your Tested-by: tag?

> I have one concern regarding dmesg output. Do you think this messaging is
> valid if possible node is not yet present?
> Or is it only the issue for virtual machines?
>
> Node XX uninitialized by the platform. Please report with boot dmesg.
> Initmem setup node XX [mem 0x0000000000000000-0x0000000000000000]

AFAIU the Initmem part of the output is what concerns you, right? Yeah,
that really is more cryptic than necessary. Does this look any better?
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 34743dcd2d66..7e18a924be7e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7618,9 +7618,14 @@ static void __init free_area_init_node(int nid)
pgdat->node_start_pfn = start_pfn;
pgdat->per_cpu_nodestats = NULL;

- pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
- (u64)start_pfn << PAGE_SHIFT,
- end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
+ if (start_pfn != end_pfn) {
+ pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
+ (u64)start_pfn << PAGE_SHIFT,
+ end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
+ } else {
+ pr_info("Initmem setup node %d as memoryless\n", nid);
+ }
+
calculate_node_totalpages(pgdat, start_pfn, end_pfn);

alloc_node_mem_map(pgdat);
--
Michal Hocko
SUSE Labs