mm: handle profiling for fake memory allocations during compaction

During compaction isolated free pages are marked allocated so that they
can be split and/or freed.  For that, post_alloc_hook() is used inside
split_map_pages() and release_free_list().  split_map_pages() marks free
pages allocated, splits the pages and then lets
alloc_contig_range_noprof() free those pages.  release_free_list() marks
free pages and immediately frees them.  This usage of post_alloc_hook()
affect memory allocation profiling because these functions might not be
called from an instrumented allocator, therefore current->alloc_tag is
NULL and when debugging is enabled (CONFIG_MEM_ALLOC_PROFILING_DEBUG=y)
that causes warnings.  To avoid that, wrap such post_alloc_hook() calls
into an instrumented function which acts as an allocator which will be
charged for these fake allocations.  Note that these allocations are very
short lived until they are freed, therefore the associated counters should
usually read 0.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Pasha Tatashin <[email protected]>
Cc: Sourav Panda <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: surenbaghdasaryan

mm/compaction.c

@@ -79,6 +79,13 @@ static inline bool is_via_compact_memory(int order) { return false; }
 #define COMPACTION_HPAGE_ORDER	(PMD_SHIFT - PAGE_SHIFT)
 #endif
 
+static struct page *mark_allocated_noprof(struct page *page, unsigned int order, gfp_t gfp_flags)
+{
+	post_alloc_hook(page, order, __GFP_MOVABLE);
+	return page;
+}
+#define mark_allocated(...)	alloc_hooks(mark_allocated_noprof(__VA_ARGS__))
+
 static void split_map_pages(struct list_head *freepages)
 {
 	unsigned int i, order;
@@ -93,7 +100,7 @@ static void split_map_pages(struct list_head *freepages)
 
 			nr_pages = 1 << order;
 
-			post_alloc_hook(page, order, __GFP_MOVABLE);
+			mark_allocated(page, order, __GFP_MOVABLE);
 			if (order)
 				split_page(page, order);
 
@@ -122,7 +129,7 @@ static unsigned long release_free_list(struct list_head *freepages)
 			 * Convert free pages into post allocation pages, so
 			 * that we can free them via __free_page.
 			 */
-			post_alloc_hook(page, order, __GFP_MOVABLE);
+			mark_allocated(page, order, __GFP_MOVABLE);
 			__free_pages(page, order);
 			if (pfn > high_pfn)
 				high_pfn = pfn;