linux-kernel - [RFC 3/7] mm/vmalloc: Avoid cond_resched() when blocking is not permitted

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Message-Id: <20250704152537.55724-4-urezki@gmail.com>
Date: Fri,  4 Jul 2025 17:25:33 +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 3/7] mm/vmalloc: Avoid cond_resched() when blocking is not permitted

The vm_area_alloc_pages() function uses cond_resched() to yield the
CPU during potentially long-running loops. However, yielding should
only be done if the given GFP flags allow blocking.

This patch avoids calling cond_resched() when the allocation context
is non-blocking(GFP_ATOMIC, GFP_NOWAIT).

Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 mm/vmalloc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8c375b8e269d..25d09f753239 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3624,7 +3624,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
 							pages + nr_allocated);
 
 			nr_allocated += nr;
-			cond_resched();
+
+			if (gfpflags_allow_blocking(gfp))
+				cond_resched();
 
 			/*
 			 * If zero or pages were obtained partly,
@@ -3666,7 +3668,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
 		for (i = 0; i < (1U << order); i++)
 			pages[nr_allocated + i] = page + i;
 
-		cond_resched();
+		if (gfpflags_allow_blocking(gfp))
+			cond_resched();
+
 		nr_allocated += 1U << order;
 	}
 
-- 
2.39.5