mm: don't account memmap on failure

Patch series "Fixes for memmap accounting", v4.

Memmap accounting provides us with observability of how much memory is
used for per-page metadata: i.e. "struct page"'s and "struct page_ext".
It also provides with information of how much was allocated using
boot allocator (i.e. not part of MemTotal), and how much was allocated
using buddy allocated (i.e. part of MemTotal).

This small series fixes a few problems that were discovered with the
original patch.


This patch (of 3):

When we fail to allocate the mmemmap in alloc_vmemmap_page_list(), do not
account any already-allocated pages: we're going to free all them before
we return from the function.

Link: https://lkml.kernel.org/r/20240809191020.1142142-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20240808213437.682006-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20240808213437.682006-2-pasha.tatashin@soleen.com
Fixes: 15995a3 ("mm: report per-page metadata information")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Joel Granados <j.granados@samsung.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Li Zhijian <lizhijian@fujitsu.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: soleen

mm/hugetlb_vmemmap.c

@@ -392,13 +392,10 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
 
 	for (i = 0; i < nr_pages; i++) {
 		page = alloc_pages_node(nid, gfp_mask, 0);
-		if (!page) {
-			mod_node_page_state(NODE_DATA(nid), NR_MEMMAP, i);
+		if (!page)
 			goto out;
-		}
 		list_add(&page->lru, list);
 	}
-
 	mod_node_page_state(NODE_DATA(nid), NR_MEMMAP, nr_pages);
 
 	return 0;