[PATCH v2] alloc_tag: handle incomplete bulk allocations in vm_module_tags_populate

[T.J. Mercier]

alloc_pages_bulk_node may partially succeed and allocate fewer than the
requested nr_pages. There are several conditions under which this can
occur, but we have encountered the case where CONFIG_PAGE_OWNER is
enabled causing all bulk allocations to always fallback to single page
allocations due to commit 187ad460b841 ("mm/page_alloc: avoid page
allocator recursion with pagesets.lock held").

Currently vm_module_tags_populate immediately fails when
alloc_pages_bulk_node returns fewer than the requested number of pages.
When this happens memory allocation profiling gets disabled, for example

[   14.297583] [9:       modprobe:  465] Failed to allocate memory for allocation tags in the module scsc_wlan. Memory allocation profiling is disabled!
[   14.299339] [9:       modprobe:  465] modprobe: Failed to insmod '/vendor/lib/modules/scsc_wlan.ko' with args '': Out of memory

This patch causes vm_module_tags_populate to retry bulk allocations for
the remaining memory instead of failing immediately which will avoid the
disablement of memory allocation profiling.

Reported-by: Janghyuck Kim <janghyuck.kim@xxxxxxxxxxx>
Fixes: 0f9b685626da ("alloc_tag: populate memory for module tags as needed")
Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx>
Acked-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
 lib/alloc_tag.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 1d893e313614..25ecc1334b67 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -422,11 +422,20 @@ static int vm_module_tags_populate(void)
 		unsigned long old_shadow_end = ALIGN(phys_end, MODULE_ALIGN);
 		unsigned long new_shadow_end = ALIGN(new_end, MODULE_ALIGN);
 		unsigned long more_pages;
-		unsigned long nr;
+		unsigned long nr = 0;
 
 		more_pages = ALIGN(new_end - phys_end, PAGE_SIZE) >> PAGE_SHIFT;
-		nr = alloc_pages_bulk_node(GFP_KERNEL | __GFP_NOWARN,
-					   NUMA_NO_NODE, more_pages, next_page);
+		while (nr < more_pages) {
+			unsigned long allocated;
+
+			allocated = alloc_pages_bulk_node(GFP_KERNEL | __GFP_NOWARN,
+				NUMA_NO_NODE, more_pages - nr, next_page + nr);
+
+			if (!allocated)
+				break;
+			nr += allocated;
+		}
+
 		if (nr < more_pages ||
 		    vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL,
 				     next_page, PAGE_SHIFT) < 0) {
-- 
2.49.0.504.g3bcea36a83-goog