[PATCH] kernel/fork.c: get totalram_pages from memblock to calculate max_threads

[PATCH] kernel/fork.c: get totalram_pages from memblock to calculate max_threads

[Wei Yang]

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@gmail.com>
CC: Mike Rapoport (IBM) <rppt@kernel.org>
CC: David Hildenbrand <david@redhat.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

Re: [PATCH] kernel/fork.c: get totalram_pages from memblock to calculate max_threads

[Oleg Nesterov]

On 06/30, Wei Yang wrote:
>
>  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());

Can't comment, I don't understand this patch.

but if you change set_max_threads, perhaps you can mark it as __init
for consistency?

Oleg.