diff options
author | Michel Lespinasse <walken@google.com> | 2013-02-27 17:02:44 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-27 19:10:09 -0800 |
commit | ff6a6da60b894d008f704fbeb5bc596f9994b16e (patch) | |
tree | 84c0fd2850edcd836afee8f9c542d4d4d98602f4 /mm/mlock.c | |
parent | c5a51053cf3b499ddba60a89ab067ea05ad15840 (diff) | |
download | lwn-ff6a6da60b894d008f704fbeb5bc596f9994b16e.tar.gz lwn-ff6a6da60b894d008f704fbeb5bc596f9994b16e.zip |
mm: accelerate munlock() treatment of THP pages
munlock_vma_pages_range() was always incrementing addresses by PAGE_SIZE
at a time. When munlocking THP pages (or the huge zero page), this
resulted in taking the mm->page_table_lock 512 times in a row.
We can do better by making use of the page_mask returned by
follow_page_mask (for the huge zero page case), or the size of the page
munlock_vma_page() operated on (for the true THP page case).
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mlock.c')
-rw-r--r-- | mm/mlock.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/mm/mlock.c b/mm/mlock.c index e6638f565d42..1c5e33fce639 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -102,13 +102,16 @@ void mlock_vma_page(struct page *page) * can't isolate the page, we leave it for putback_lru_page() and vmscan * [page_referenced()/try_to_unmap()] to deal with. */ -void munlock_vma_page(struct page *page) +unsigned int munlock_vma_page(struct page *page) { + unsigned int page_mask = 0; + BUG_ON(!PageLocked(page)); if (TestClearPageMlocked(page)) { - mod_zone_page_state(page_zone(page), NR_MLOCK, - -hpage_nr_pages(page)); + unsigned int nr_pages = hpage_nr_pages(page); + mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); + page_mask = nr_pages - 1; if (!isolate_lru_page(page)) { int ret = SWAP_AGAIN; @@ -141,6 +144,8 @@ void munlock_vma_page(struct page *page) count_vm_event(UNEVICTABLE_PGMUNLOCKED); } } + + return page_mask; } /** @@ -159,7 +164,6 @@ long __mlock_vma_pages_range(struct vm_area_struct *vma, unsigned long start, unsigned long end, int *nonblocking) { struct mm_struct *mm = vma->vm_mm; - unsigned long addr = start; unsigned long nr_pages = (end - start) / PAGE_SIZE; int gup_flags; @@ -189,7 +193,7 @@ long __mlock_vma_pages_range(struct vm_area_struct *vma, * We made sure addr is within a VMA, so the following will * not result in a stack expansion that recurses back here. */ - return __get_user_pages(current, mm, addr, nr_pages, gup_flags, + return __get_user_pages(current, mm, start, nr_pages, gup_flags, NULL, NULL, nonblocking); } @@ -226,13 +230,12 @@ static int __mlock_posix_error_return(long retval) void munlock_vma_pages_range(struct vm_area_struct *vma, unsigned long start, unsigned long end) { - unsigned long addr; - - lru_add_drain(); vma->vm_flags &= ~VM_LOCKED; - for (addr = start; addr < end; addr += PAGE_SIZE) { + while (start < end) { struct page *page; + unsigned int page_mask, page_increm; + /* * Although FOLL_DUMP is intended for get_dump_page(), * it just so happens that its special treatment of the @@ -240,13 +243,22 @@ void munlock_vma_pages_range(struct vm_area_struct *vma, * suits munlock very well (and if somehow an abnormal page * has sneaked into the range, we won't oops here: great). */ - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page = follow_page_mask(vma, start, FOLL_GET | FOLL_DUMP, + &page_mask); if (page && !IS_ERR(page)) { lock_page(page); - munlock_vma_page(page); + lru_add_drain(); + /* + * Any THP page found by follow_page_mask() may have + * gotten split before reaching munlock_vma_page(), + * so we need to recompute the page_mask here. + */ + page_mask = munlock_vma_page(page); unlock_page(page); put_page(page); } + page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask); + start += page_increm * PAGE_SIZE; cond_resched(); } } |