Re: [PATCH] mm/page_alloc: remove the static for local variable node_order
From: Michal Hocko <mhocko@suse.com>
Date: 2021-01-05 07:29:53
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On Mon 04-01-21 15:23:57, Andrew Morton wrote:
On Wed, 30 Dec 2020 12:42:33 +0000 Matthew Wilcox [off-list ref] wrote:quoted
On Wed, Dec 30, 2020 at 07:40:14PM +0800, Hui Su wrote:quoted
local variable node_order do not need the static here.It bloody well does. It can be up to 2^10 entries on x86 (and larger on others) That's 4kB which you've now moved onto the stack.That being said, could we kmalloc the scratch area in __build_all_zonelists()? And maybe remove that static spinlock?
I am not sure we can (e.g. early init code) but even if we could, what would be an advantage. This code is called very seldom with a very shallow stacks so using the stack allocation sounds like the easiest thing to do.
(what blocks node and cpu hotplug in there??)
Memory hotplug is excluded by the caller when it matters (e.g. no locking for the early init). -- Michal Hocko SUSE Labs