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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: f000565adb ("thp: set recommended min free kbytes")
Signed-off-by: Vijay Balakrishna <vijayb@linux.microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vijay Balakrishna 2020-10-10 23:16:40 -07:00 committed by Linus Torvalds
parent 8b7b2eb131
commit 4aab2be098
3 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/khugepaged.h
View File

@ -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 */

13
mm/khugepaged.c
View File

@ -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);
}

3
mm/page_alloc.c
View File

@ -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)