Commit 4aab2be0 authored by Vijay Balakrishna's avatar Vijay Balakrishna Committed by Linus Torvalds
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mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged 

When memory is hotplug added or removed the min_free_kbytes should be
recalculated based on what is expected by khugepaged.  Currently after
hotplug, min_free_kbytes will be set to a lower default and higher
default set when THP enabled is lost.

This change restores min_free_kbytes as expected for THP consumers.

[vijayb@linux.microsoft.com: v5]
  Link: https://lkml.kernel.org/r/1601398153-5517-1-git-send-email-vijayb@linux.microsoft.com



Fixes: f000565a ("thp: set recommended min free kbytes")
Signed-off-by: default avatarVijay Balakrishna <vijayb@linux.microsoft.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarPavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Allen Pais <apais@microsoft.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/1600305709-2319-2-git-send-email-vijayb@linux.microsoft.com
Link: https://lkml.kernel.org/r/1600204258-13683-1-git-send-email-vijayb@linux.microsoft.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8b7b2eb1

include/linux/khugepaged.h

+5 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ extern int __khugepaged_enter(struct mm_struct *mm); 
extern void __khugepaged_exit(struct mm_struct *mm);

extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma,

				      unsigned long vm_flags);

extern void khugepaged_min_free_kbytes_update(void);

#ifdef CONFIG_SHMEM

extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr);

#else
@@ -85,6 +86,10 @@ static inline void collapse_pte_mapped_thp(struct mm_struct *mm, 
					   unsigned long addr)

{

}



static inline void khugepaged_min_free_kbytes_update(void)

{

}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



#endif /* _LINUX_KHUGEPAGED_H */

mm/khugepaged.c

+11 −2
Original line number Diff line number Diff line
@@ -56,6 +56,9 @@ enum scan_result { 
#define CREATE_TRACE_POINTS

#include <trace/events/huge_memory.h>



static struct task_struct *khugepaged_thread __read_mostly;

static DEFINE_MUTEX(khugepaged_mutex);



/* default scan 8*512 pte (or vmas) every 30 second */

static unsigned int khugepaged_pages_to_scan __read_mostly;

static unsigned int khugepaged_pages_collapsed;
@@ -2304,8 +2307,6 @@ static void set_recommended_min_free_kbytes(void) 


int start_stop_khugepaged(void)

{

	static struct task_struct *khugepaged_thread __read_mostly;

	static DEFINE_MUTEX(khugepaged_mutex);

	int err = 0;



	mutex_lock(&khugepaged_mutex);
@@ -2332,3 +2333,11 @@ fail: 
	mutex_unlock(&khugepaged_mutex);

	return err;

}



void khugepaged_min_free_kbytes_update(void)

{

	mutex_lock(&khugepaged_mutex);

	if (khugepaged_enabled() && khugepaged_thread)

		set_recommended_min_free_kbytes();

	mutex_unlock(&khugepaged_mutex);

}

mm/page_alloc.c

+3 −0
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ 
#include <linux/nmi.h>

#include <linux/psi.h>

#include <linux/padata.h>

#include <linux/khugepaged.h>



#include <asm/sections.h>

#include <asm/tlbflush.h>
@@ -7904,6 +7905,8 @@ int __meminit init_per_zone_wmark_min(void) 
	setup_min_slab_ratio();

#endif



	khugepaged_min_free_kbytes_update();



	return 0;

}

postcore_initcall(init_per_zone_wmark_min)

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