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mm: make try_to_munlock() return void

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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: Minchan Kim <minchan@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2017-05-03 14:54:10 -07:00 • committed by Linus Torvalds
parent 22ffb33f46
commit 192d723256
3 changed files with 7 additions and 17 deletions
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2
include/linux/rmap.h
View file

@ -235,7 +235,7 @@ int page_mkclean(struct page *);
* called in munlock()/munmap() path to check for other vmas holding * called in munlock()/munmap() path to check for other vmas holding
* the page mlocked. * 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); void remove_migration_ptes(struct page *old, struct page *new, bool locked);

6
mm/mlock.c
View file

@ -123,17 +123,15 @@ static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
*/ */
static void __munlock_isolated_page(struct page *page) static void __munlock_isolated_page(struct page *page)
{ {
int ret = SWAP_AGAIN;
/* /*
* Optimization: if the page was mapped just once, that's our mapping * Optimization: if the page was mapped just once, that's our mapping
* and we don't need to check all the other vmas. * and we don't need to check all the other vmas.
*/ */
if (page_mapcount(page) > 1) if (page_mapcount(page) > 1)
ret = try_to_munlock(page); try_to_munlock(page);
/* Did try_to_unlock() succeed or punt? */ /* Did try_to_unlock() succeed or punt? */
if (ret != SWAP_MLOCK) if (!PageMlocked(page))
count_vm_event(UNEVICTABLE_PGMUNLOCKED); count_vm_event(UNEVICTABLE_PGMUNLOCKED);
putback_lru_page(page); putback_lru_page(page);

16
mm/rmap.c
View file

@ -1552,18 +1552,10 @@ static int page_not_mapped(struct page *page)
* Called from munlock code. Checks all of the VMAs mapping the 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 * 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. * 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 = { struct rmap_walk_control rwc = {
.rmap_one = try_to_unmap_one, .rmap_one = try_to_unmap_one,
.arg = (void *)TTU_MUNLOCK, .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(!PageLocked(page) || PageLRU(page), page);
VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
ret = rmap_walk(page, &rwc); rmap_walk(page, &rwc);
return ret;
} }
void __put_anon_vma(struct anon_vma *anon_vma) void __put_anon_vma(struct anon_vma *anon_vma)