Patch "mm: update min_free_kbytes from khugepaged after core initialization" has been added to the 4.5-stable tree

This is a note to let you know that I've just added the patch titled

mm: update min_free_kbytes from khugepaged after core initialization

to the 4.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mm-update-min_free_kbytes-from-khugepaged-after-core-initialization.patch
and it can be found in the queue-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jason Baron <[email protected]>
Date: Thu, 5 May 2016 16:22:12 -0700
Subject: mm: update min_free_kbytes from khugepaged after core initialization

From: Jason Baron <[email protected]>

commit bc22af74f271ef76b2e6f72f3941f91f0da3f5f8 upstream.

Khugepaged attempts to raise min_free_kbytes if its set too low. However, on boot khugepaged sets min_free_kbytes first from subsys_initcall(), and then the mm 'core' over-rides min_free_kbytes after from init_per_zone_wmark_min(), via a module_init() call.

Khugepaged used to use a late_initcall() to set min_free_kbytes (such that it occurred after the core initialization), however this was removed when the initialization of min_free_kbytes was integrated into the starting of the khugepaged thread.

The fix here is simply to invoke the core initialization using a core_initcall() instead of module_init(), such that the previous initialization ordering is restored. I didn't restore the late_initcall() since start_stop_khugepaged() already sets min_free_kbytes via set_recommended_min_free_kbytes().

This was noticed when we had a number of page allocation failures when moving a workload to a kernel with this new initialization ordering. On an 8GB system this restores min_free_kbytes back to 67584 from 11365 when CONFIG_TRANSPARENT_HUGEPAGE=y is set and either CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS=y or CONFIG_TRANSPARENT_HUGEPAGE_MADVISE=y.

---
 mm/page_alloc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -6214,7 +6214,7 @@ int __meminit init_per_zone_wmark_min(vo
 	setup_per_zone_inactive_ratio();
 	return 0;
 }
-module_init(init_per_zone_wmark_min)
+core_initcall(init_per_zone_wmark_min)
 
 /*
  * min_free_kbytes_sysctl_handler - just a wrapper around proc_dointvec() so

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/mm-update-min_free_kbytes-from-khugepaged-after-core-initialization.patch