linux-kernel - [RFC 7/7] mm: Drop __GFP_DIRECT_RECLAIM flag if PF

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Message-Id: <20250704152537.55724-8-urezki@gmail.com>
Date: Fri,  4 Jul 2025 17:25:37 +0200
From: "Uladzislau Rezki (Sony)" <urezki@...il.com>
To: linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Baoquan He <bhe@...hat.com>,
	Uladzislau Rezki <urezki@...il.com>
Subject: [RFC 7/7] mm: Drop __GFP_DIRECT_RECLAIM flag if PF_MEMALLOC is set

The memory allocator already avoids reclaim when PF_MEMALLOC is set.
Clear __GFP_DIRECT_RECLAIM explicitly to suppress might_alloc() warnings
to make more correct behavior.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 include/linux/sched/mm.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index b13474825130..40757173acb1 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -246,12 +246,14 @@ static inline bool in_vfork(struct task_struct *tsk)
  * PF_MEMALLOC_NOIO implies GFP_NOIO
  * PF_MEMALLOC_NOFS implies GFP_NOFS
  * PF_MEMALLOC_PIN  implies !GFP_MOVABLE
+ * PF_MEMALLOC      implies !__GFP_DIRECT_RECLAIM
  */
 static inline gfp_t current_gfp_context(gfp_t flags)
 {
 	unsigned int pflags = READ_ONCE(current->flags);
 
-	if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_PIN))) {
+	if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS |
+			PF_MEMALLOC_PIN | PF_MEMALLOC))) {
 		/*
 		 * NOIO implies both NOIO and NOFS and it is a weaker context
 		 * so always make sure it makes precedence
@@ -263,6 +265,9 @@ static inline gfp_t current_gfp_context(gfp_t flags)
 
 		if (pflags & PF_MEMALLOC_PIN)
 			flags &= ~__GFP_MOVABLE;
+
+		if (pflags & PF_MEMALLOC)
+			flags &= ~__GFP_DIRECT_RECLAIM;
 	}
 	return flags;
 }
-- 
2.39.5