check_and_migrate_cma_pages

Name:check_and_migrate_cma_pages

Proto:static long check_and_migrate_cma_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, struct page **pages, struct vm_area_struct **vmas, unsigned int gup_flags)

Type:long

Parameter:

Type	Parameter	Name
struct task_struct *	tsk
struct mm_struct *	mm
unsigned long	start
unsigned long	nr_pages
struct page **	pages
struct vm_area_struct **	vmas
unsigned int	gup_flags

1455

bool drain_allow = true

1456

bool migrate_allow = true

1457

LIST_HEAD(cma_page_list)

1458

1460

1461

When i < nr_pages cycle

1463

head = compound_head(pages[i])

1469

step = Returns the number of pages in this potentially compound page. - pages[i] - head

1475

If is_migrate_cma_page(head) Then

1476

If PageHuge(head) Then isolate_huge_page(head, & cma_page_list)

1478

Else

1479

If Not PageLRU(head) && drain_allow Then

1480

lru_add_drain_all()

1481

drain_allow = false

1484

If Not solate_lru_page - tries to isolate a page from its LRU list*@page: page to isolate from its LRU list* Isolates a @page from an LRU list, clears PageLRU and adjusts the* vmstat statistic corresponding to whatever LRU list the page was on. Then

1485

list_add_tail - add a new entry*@new: new entry to be added*@head: list head to add it before* Insert a new entry before the specified head.* This is useful for implementing queues.

1486

mod_node_page_state(page_pgdat(head), Temporary isolated pages from anon lru + page_is_file_cache - should the page be on a file LRU or anon LRU?*@page: the page to test* Returns 1 if @page is page cache page backed by a regular filesystem,* or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed, hpage_nr_pages(head))

1494

i += step

1497

If Not list_empty - tests whether a list is empty*@head: the list to test. Then

1501

When i < nr_pages cycle put_page(pages[i])

1504

If migrate_pages - migrate the pages specified in a list, to the free pages* supplied as the target for the page migration*@from: The list of pages to be migrated.*@get_new_page: The function used to allocate free pages to be used Then

1510

migrate_allow = false

1512

If Not list_empty - tests whether a list is empty*@head: the list to test. Then Put previously isolated pages back onto the appropriate lists* from where they were once taken off for compaction/migration.* This function shall be used whenever the isolated pageset has been* built from lru, balloon, hugetlbfs page

1520

ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas, NULL, gup_flags)

1524

If ret > 0 && migrate_allow Then

1525

1526

drain_allow = true

1527

Go to check_again

1531

Return ret

**Caller**
Name	Describe
__gup_longterm_locked	__gup_longterm_locked() is a wrapper for __get_user_pages_locked which* allows us to process the FOLL_LONGTERM flag.

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