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Commit 192d7232 authored by Minchan Kim's avatar Minchan Kim Committed by Linus Torvalds
Browse files

mm: make try_to_munlock() return void 

try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped the page has
VM_LOCKED flag.  In that time, VM set PG_mlocked to the page if the page
is not pte-mapped THP which cannot be mlocked, either.

With that, __munlock_isolated_page can use PageMlocked to check whether
try_to_munlock is successful or not without relying on try_to_munlock's
retval.  It helps to make try_to_unmap/try_to_unmap_one simple with
upcoming patches.

[minchan@kernel.org: remove PG_Mlocked VM_BUG_ON check]
  Link: http://lkml.kernel.org/r/20170411025615.GA6545@bbox
Link: http://lkml.kernel.org/r/1489555493-14659-5-git-send-email-minchan@kernel.org


Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 22ffb33f

include/linux/rmap.h

+1 −1
Original line number Diff line number Diff line
@@ -235,7 +235,7 @@ int page_mkclean(struct page *); 
 * called in munlock()/munmap() path to check for other vmas holding

 * the page mlocked.

 */

int try_to_munlock(struct page *);

void try_to_munlock(struct page *);



void remove_migration_ptes(struct page *old, struct page *new, bool locked);

mm/mlock.c

+2 −4
Original line number Diff line number Diff line
@@ -123,17 +123,15 @@ static bool __munlock_isolate_lru_page(struct page *page, bool getpage) 
 */

static void __munlock_isolated_page(struct page *page)

{

	int ret = SWAP_AGAIN;



	/*

	 * Optimization: if the page was mapped just once, that's our mapping

	 * and we don't need to check all the other vmas.

	 */

	if (page_mapcount(page) > 1)

		ret = try_to_munlock(page);

		try_to_munlock(page);



	/* Did try_to_unlock() succeed or punt? */

	if (ret != SWAP_MLOCK)

	if (!PageMlocked(page))

		count_vm_event(UNEVICTABLE_PGMUNLOCKED);



	putback_lru_page(page);

mm/rmap.c

+4 −12
Original line number Diff line number Diff line
@@ -1552,18 +1552,10 @@ static int page_not_mapped(struct page *page) 
 * Called from munlock code.  Checks all of the VMAs mapping the page

 * to make sure nobody else has this page mlocked. The page will be

 * returned with PG_mlocked cleared if no other vmas have it mlocked.

 *

 * Return values are:

 *

 * SWAP_AGAIN	- no vma is holding page mlocked, or,

 * SWAP_AGAIN	- page mapped in mlocked vma -- couldn't acquire mmap sem

 * SWAP_FAIL	- page cannot be located at present

 * SWAP_MLOCK	- page is now mlocked.

 */

int try_to_munlock(struct page *page)

{

	int ret;



void try_to_munlock(struct page *page)

{

	struct rmap_walk_control rwc = {

		.rmap_one = try_to_unmap_one,

		.arg = (void *)TTU_MUNLOCK,
@@ -1573,9 +1565,9 @@ int try_to_munlock(struct page *page) 
	};



	VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);

	VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);



	ret = rmap_walk(page, &rwc);

	return ret;

	rmap_walk(page, &rwc);

}



void __put_anon_vma(struct anon_vma *anon_vma)