On Mon, 1 Jul 2024 01:34:09 +0000 Wei Yang <richard.weiyang@xxxxxxxxx> wrote:
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.
Yes, things like totalram_pages() are very old, and were a good idea at the
time, but things moved on.
Instead we can get the total usable pages from memblock directly.
--- 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 result of this subtraction has meaning. Even if it is only used
once, I suspect it should be in a standalone function which has
documentation which describes that meaning. Having fork.c make an
open-coded poke into memblock internals seems wrong, no?