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thp: freeze khugepaged and ksmd

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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: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli 2011-01-13 15:47:10 -08:00 committed by Linus Torvalds
parent 8ee53820ed
commit 878aee7d6b
2 changed files with 18 additions and 4 deletions
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14
mm/huge_memory.c
View file

@ -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)
@ -2157,8 +2164,8 @@ static void khugepaged_loop(void)
khugepaged_scan_sleep_millisecs));
remove_wait_queue(&khugepaged_wait, &wait);
} else if (khugepaged_enabled())
wait_event_interruptible(khugepaged_wait,
khugepaged_wait_event());
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);

8
mm/ksm.c
View file

@ -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());
}
}