Re: regression in /proc/self/numa_maps with huge pages

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 19 Oct 2011 12:35:30 -0700
Stephen Hemminger <shemminger@vyatta.com> wrote:

> We are working on an application that uses a library that uses
> both huge pages and parses numa_maps.  This application is no longer
> able to identify the socket id correctly for huge pages because the
> that 'huge' is no longer part of /proc/self/numa_maps.
> 
> Basically, application sets up huge page mmaps, then reads /proc/self/numa_maps
> and skips all entries without the string " huge ".  Then it looks for address
> and socket info.
> 
> Why was this information dropped?

Mistake?

> Looks like the desire to be generic
> overstepped the desire to remain compatible.

Or it was a mistake.

This?

--- a/fs/proc/task_mmu.c~a
+++ a/fs/proc/task_mmu.c
@@ -1009,6 +1009,9 @@ static int show_numa_map(struct seq_file
 		seq_printf(m, " stack");
 	}
 
+	if (is_vm_hugetlb_page(vma))
+		seq_printf(m, " huge");
+
 	walk_page_range(vma->vm_start, vma->vm_end, &walk);
 
 	if (!md->pages)

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