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Commit d516904b authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Linus Torvalds
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thp: merge page pre-alloc in khugepaged_loop into khugepaged_do_scan 



There are two pre-alloc operations in these two function, the different is:
- it allows to sleep if page alloc fail in khugepaged_loop
- it exits immediately if page alloc fail in khugepaged_do_scan

Actually, in khugepaged_do_scan, we can allow the pre-alloc to sleep on
the first failure, then the operation in khugepaged_loop can be removed

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9817626e

mm/huge_memory.c

+45 −52
Original line number Diff line number Diff line
@@ -2222,10 +2222,40 @@ static int khugepaged_wait_event(void) 
		kthread_should_stop();

}



static void khugepaged_do_scan(struct page **hpage)

static void khugepaged_alloc_sleep(void)

{

	wait_event_freezable_timeout(khugepaged_wait, false,

			msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));

}



#ifndef CONFIG_NUMA

static struct page *khugepaged_alloc_hugepage(bool *wait)

{

	struct page *hpage;



	do {

		hpage = alloc_hugepage(khugepaged_defrag());

		if (!hpage) {

			count_vm_event(THP_COLLAPSE_ALLOC_FAILED);

			if (!*wait)

				return NULL;



			*wait = false;

			khugepaged_alloc_sleep();

		} else

			count_vm_event(THP_COLLAPSE_ALLOC);

	} while (unlikely(!hpage) && likely(khugepaged_enabled()));



	return hpage;

}

#endif



static void khugepaged_do_scan(void)

{

	struct page *hpage = NULL;

	unsigned int progress = 0, pass_through_head = 0;

	unsigned int pages = khugepaged_pages_to_scan;

	bool wait = true;



	barrier(); /* write khugepaged_pages_to_scan to local stack */
@@ -2233,17 +2263,18 @@ static void khugepaged_do_scan(struct page **hpage) 
		cond_resched();



#ifndef CONFIG_NUMA

		if (!*hpage) {

			*hpage = alloc_hugepage(khugepaged_defrag());

			if (unlikely(!*hpage)) {

				count_vm_event(THP_COLLAPSE_ALLOC_FAILED);

		if (!hpage)

			hpage = khugepaged_alloc_hugepage(&wait);



		if (unlikely(!hpage))

			break;

			}

			count_vm_event(THP_COLLAPSE_ALLOC);

		}

#else

		if (IS_ERR(*hpage))

		if (IS_ERR(hpage)) {

			if (!wait)

				break;

			wait = false;

			khugepaged_alloc_sleep();

		}

#endif



		if (unlikely(kthread_should_stop() || freezing(current)))
@@ -2255,36 +2286,15 @@ static void khugepaged_do_scan(struct page **hpage) 
		if (khugepaged_has_work() &&

		    pass_through_head < 2)

			progress += khugepaged_scan_mm_slot(pages - progress,

							    hpage);

							    &hpage);

		else

			progress = pages;

		spin_unlock(&khugepaged_mm_lock);

	}

}



static void khugepaged_alloc_sleep(void)

{

	wait_event_freezable_timeout(khugepaged_wait, false,

			msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));

}



#ifndef CONFIG_NUMA

static struct page *khugepaged_alloc_hugepage(void)

{

	struct page *hpage;



	do {

		hpage = alloc_hugepage(khugepaged_defrag());

		if (!hpage) {

			count_vm_event(THP_COLLAPSE_ALLOC_FAILED);

			khugepaged_alloc_sleep();

		} else

			count_vm_event(THP_COLLAPSE_ALLOC);

	} while (unlikely(!hpage) &&

		 likely(khugepaged_enabled()));

	return hpage;

	if (!IS_ERR_OR_NULL(hpage))

		put_page(hpage);

}

#endif



static void khugepaged_wait_work(void)

{
@@ -2306,25 +2316,8 @@ static void khugepaged_wait_work(void) 


static void khugepaged_loop(void)

{

	struct page *hpage = NULL;



	while (likely(khugepaged_enabled())) {

#ifndef CONFIG_NUMA

		hpage = khugepaged_alloc_hugepage();

		if (unlikely(!hpage))

			break;

#else

		if (IS_ERR(hpage)) {

			khugepaged_alloc_sleep();

			hpage = NULL;

		}

#endif



		khugepaged_do_scan(&hpage);



		if (!IS_ERR_OR_NULL(hpage))

			put_page(hpage);



		khugepaged_do_scan();

		khugepaged_wait_work();

	}

}