[PATCH 1/4] mm: page_alloc: __GFP_FS lockdep annotation for direct compaction

[Johannes Weiner]

A subsequent patch will have some order-0 allocations participate in
compaction under defrag_mode, to stave off extfrag events.

Since this is a sprawling expansion of entry points, and compaction
can enter filesystem paths, add lockdep annotations that catches
__GFP_FS passing errors.

Direct reclaim has had this annotation for a while, and since reclaim
and compaction are usually used in conjunction, this is unlikely to
unearth old bugs. It's more about future proofing and peace of mind.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 mm/page_alloc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ee902a468c2f..cb422505c6ef 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4152,12 +4152,14 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 
 	psi_memstall_enter(&pflags);
 	delayacct_compact_start();
+	fs_reclaim_acquire(gfp_mask);
 	noreclaim_flag = memalloc_noreclaim_save();
 
 	*compact_result = try_to_compact_pages(gfp_mask, order, alloc_flags, ac,
 								prio, &page);
 
 	memalloc_noreclaim_restore(noreclaim_flag);
+	fs_reclaim_release(gfp_mask);
 	psi_memstall_leave(&pflags);
 	delayacct_compact_end();
 
-- 
2.54.0