The patch titled
Subject: mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged
has been added to the -mm tree. Its filename is
mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Vijay Balakrishna <vijayb@xxxxxxxxxxxxxxxxxxx>
Subject: mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged
When memory is hotplug added or removed the min_free_kbytes must 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 leaves the system with small
min_free_kbytes which isn't suitable for systems especially with network
intensive loads. Typical failure symptoms include HW WATCHDOG reset, soft
lockup hang notices, NETDEVICE WATCHDOG timeouts, and OOM process kills.
Link: https://lkml.kernel.org/r/1600204258-13683-1-git-send-email-vijayb@xxxxxxxxxxxxxxxxxxx
Fixes: f000565adb77 ("thp: set recommended min free kbytes")
Signed-off-by: Vijay Balakrishna <vijayb@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Allen Pais <apais@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/khugepaged.h | 5 +++++
mm/khugepaged.c | 13 +++++++++++--
mm/memory_hotplug.c | 3 +++
3 files changed, 19 insertions(+), 2 deletions(-)
--- a/include/linux/khugepaged.h~mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged
+++ a/include/linux/khugepaged.h
@@ -15,6 +15,7 @@ extern int __khugepaged_enter(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_t
unsigned long addr)
{
}
+
+static inline void khugepaged_min_free_kbytes_update(void)
+{
+}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif /* _LINUX_KHUGEPAGED_H */
--- a/mm/khugepaged.c~mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged
+++ a/mm/khugepaged.c
@@ -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;
@@ -2292,8 +2295,6 @@ static void set_recommended_min_free_kby
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);
@@ -2320,3 +2321,11 @@ 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);
+}
--- a/mm/memory_hotplug.c~mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged
+++ a/mm/memory_hotplug.c
@@ -36,6 +36,7 @@
#include <linux/memblock.h>
#include <linux/compaction.h>
#include <linux/rmap.h>
+#include <linux/khugepaged.h>
#include <asm/tlbflush.h>
@@ -857,6 +858,7 @@ int __ref online_pages(unsigned long pfn
zone_pcp_update(zone);
init_per_zone_wmark_min();
+ khugepaged_min_free_kbytes_update();
kswapd_run(nid);
kcompactd_run(nid);
@@ -1614,6 +1616,7 @@ static int __ref __offline_pages(unsigne
pgdat_resize_unlock(zone->zone_pgdat, &flags);
init_per_zone_wmark_min();
+ khugepaged_min_free_kbytes_update();
if (!populated_zone(zone)) {
zone_pcp_reset(zone);
_
Patches currently in -mm which might be from vijayb@xxxxxxxxxxxxxxxxxxx are
mm-khugepaged-recalculate-min_free_kbytes-after-memory-hotplug-as-expected-by-khugepaged.patch
mm-khugepaged-avoid-overriding-min_free_kbytes-set-by-user.patch
