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Commit 878aee7d authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

thp: freeze khugepaged and ksmd 



It's unclear why schedule friendly kernel threads can't be taken away by
the CPU through the scheduler itself.  It's safer to stop them as they can
trigger memory allocation, if kswapd also freezes itself to avoid
generating I/O they have too.

Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8ee53820

mm/huge_memory.c

+12 −2
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/mm_inline.h>

#include <linux/kthread.h>

#include <linux/khugepaged.h>

#include <linux/freezer.h>

#include <asm/tlb.h>

#include <asm/pgalloc.h>

#include "internal.h"
@@ -2085,6 +2086,9 @@ static void khugepaged_do_scan(struct page **hpage) 
			break;

#endif



		if (unlikely(kthread_should_stop() || freezing(current)))

			break;



		spin_lock(&khugepaged_mm_lock);

		if (!khugepaged_scan.mm_slot)

			pass_through_head++;
@@ -2147,6 +2151,9 @@ static void khugepaged_loop(void) 
		if (hpage)

			put_page(hpage);

#endif

		try_to_freeze();

		if (unlikely(kthread_should_stop()))

			break;

		if (khugepaged_has_work()) {

			DEFINE_WAIT(wait);

			if (!khugepaged_scan_sleep_millisecs)
@@ -2157,7 +2164,7 @@ static void khugepaged_loop(void) 
					khugepaged_scan_sleep_millisecs));

			remove_wait_queue(&khugepaged_wait, &wait);

		} else if (khugepaged_enabled())

			wait_event_interruptible(khugepaged_wait,

			wait_event_freezable(khugepaged_wait,

					     khugepaged_wait_event());

	}

}
@@ -2166,6 +2173,7 @@ static int khugepaged(void *none) 
{

	struct mm_slot *mm_slot;



	set_freezable();

	set_user_nice(current, 19);



	/* serialize with start_khugepaged() */
@@ -2180,6 +2188,8 @@ static int khugepaged(void *none) 
		mutex_lock(&khugepaged_mutex);

		if (!khugepaged_enabled())

			break;

		if (unlikely(kthread_should_stop()))

			break;

	}



	spin_lock(&khugepaged_mm_lock);

mm/ksm.c

+6 −2
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/swap.h>

#include <linux/ksm.h>

#include <linux/hash.h>

#include <linux/freezer.h>



#include <asm/tlbflush.h>

#include "internal.h"
@@ -1365,7 +1366,7 @@ static void ksm_do_scan(unsigned int scan_npages) 
	struct rmap_item *rmap_item;

	struct page *uninitialized_var(page);



	while (scan_npages--) {

	while (scan_npages-- && likely(!freezing(current))) {

		cond_resched();

		rmap_item = scan_get_next_rmap_item(&page);

		if (!rmap_item)
@@ -1383,6 +1384,7 @@ static int ksmd_should_run(void) 


static int ksm_scan_thread(void *nothing)

{

	set_freezable();

	set_user_nice(current, 5);



	while (!kthread_should_stop()) {
@@ -1391,11 +1393,13 @@ static int ksm_scan_thread(void *nothing) 
			ksm_do_scan(ksm_thread_pages_to_scan);

		mutex_unlock(&ksm_thread_mutex);



		try_to_freeze();



		if (ksmd_should_run()) {

			schedule_timeout_interruptible(

				msecs_to_jiffies(ksm_thread_sleep_millisecs));

		} else {

			wait_event_interruptible(ksm_thread_wait,

			wait_event_freezable(ksm_thread_wait,

				ksmd_should_run() || kthread_should_stop());

		}

	}