linux-kernel - [PATCH 4/8] mm/vmalloc: Remove cond_resched() in vm_area_alloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250807075810.358714-5-urezki@gmail.com>
Date: Thu,  7 Aug 2025 09:58:06 +0200
From: "Uladzislau Rezki (Sony)" <urezki@...il.com>
To: linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>
Cc: Vlastimil Babka <vbabka@...e.cz>,
	Michal Hocko <mhocko@...nel.org>,
	Baoquan He <bhe@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Uladzislau Rezki <urezki@...il.com>
Subject: [PATCH 4/8] mm/vmalloc: Remove cond_resched() in vm_area_alloc_pages()

The vm_area_alloc_pages() function uses cond_resched() to yield the
CPU during potentially long-running loops. However, these loops are
not considered long-running under normal conditions. In non-blocking
contexts, calling cond_resched() is inappropriate also.

Remove these calls to ensure correctness for blocking/non-blocking
contexts. This also simplifies the code path. In fact, a slow path
of page allocator already includes reschedule points to mitigate
latency.

This patch was tested for !CONFIG_PREEMPT kernel and with large
allocation chunks(~1GB), without triggering any "BUG: soft lockup"
warnings.

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

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 81b6d3bde719..b0255e0c74b3 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3633,7 +3633,6 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
 							pages + nr_allocated);

 			nr_allocated += nr;
-			cond_resched();

 			/*
 			 * If zero or pages were obtained partly,
@@ -3675,7 +3674,6 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
 		for (i = 0; i < (1U << order); i++)
 			pages[nr_allocated + i] = page + i;

-		cond_resched();
 		nr_allocated += 1U << order;
 	}

-- 
2.39.5