linux-kernel - [PATCH v2 1/2] kernel/fork.c: get totalram_pages from memblock to calculate max

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Message-Id: <20240701013410.17260-1-richard.weiyang@gmail.com>
Date: Mon,  1 Jul 2024 01:34:09 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: akpm@...ux-foundation.org,
	brauner@...nel.org,
	oleg@...hat.com,
	mjguzik@...il.com,
	tandersen@...flix.com
Cc: linux-kernel@...r.kernel.org,
	Wei Yang <richard.weiyang@...il.com>,
	Mike Rapoport <rppt@...nel.org>,
	David Hildenbrand <david@...hat.com>
Subject: [PATCH v2 1/2] kernel/fork.c: get totalram_pages from memblock to calculate max_threads

Since we plan to move the accounting into __free_pages_core(),
totalram_pages may not represent the total usable pages on system
at this point when defer_init is enabled.

Instead we can get the total usable pages from memblock directly.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
CC: Mike Rapoport (IBM) <rppt@...nel.org>
CC: David Hildenbrand <david@...hat.com>
CC: Oleg Nesterov <oleg@...hat.com>
---
 kernel/fork.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 99076dbe27d8..eb2b5f96aa61 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -44,6 +44,7 @@
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/mm_inline.h>
+#include <linux/memblock.h>
 #include <linux/nsproxy.h>
 #include <linux/capability.h>
 #include <linux/cpu.h>
@@ -999,7 +1000,7 @@ void __init __weak arch_task_cache_init(void) { }
 static void set_max_threads(unsigned int max_threads_suggested)
 {
 	u64 threads;
-	unsigned long nr_pages = totalram_pages();
+	unsigned long nr_pages = PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size());
 
 	/*
 	 * The number of threads shall be limited such that the thread
-- 
2.34.1