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authorMichel Lespinasse <walken@google.com>2011-01-13 15:46:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:36 -0800
commit110d74a921f4d272b47ef6104fcf937df808f4c8 (patch)
treea2f1705e049f06e1cf8cbaf7d6b3261f0b46b6ab /mm/memory.c
parentfed067da46ad3b9acedaf794a5f05d0bc153280b (diff)
downloadop-kernel-dev-110d74a921f4d272b47ef6104fcf937df808f4c8.zip
op-kernel-dev-110d74a921f4d272b47ef6104fcf937df808f4c8.tar.gz
mm: add FOLL_MLOCK follow_page flag.
Move the code to mlock pages from __mlock_vma_pages_range() to follow_page(). This allows __mlock_vma_pages_range() to not have to break down work into 16-page batches. An additional motivation for doing this within the present patch series is that it'll make it easier for a later chagne to drop mmap_sem when blocking on disk (we'd like to be able to resume at the page that was read from disk instead of at the start of a 16-page batch). Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index b8f97b8..15e1f19 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1310,6 +1310,28 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
*/
mark_page_accessed(page);
}
+ if (flags & FOLL_MLOCK) {
+ /*
+ * The preliminary mapping check is mainly to avoid the
+ * pointless overhead of lock_page on the ZERO_PAGE
+ * which might bounce very badly if there is contention.
+ *
+ * If the page is already locked, we don't need to
+ * handle it now - vmscan will handle it later if and
+ * when it attempts to reclaim the page.
+ */
+ if (page->mapping && trylock_page(page)) {
+ lru_add_drain(); /* push cached pages to LRU */
+ /*
+ * Because we lock page here and migration is
+ * blocked by the pte's page reference, we need
+ * only check for file-cache page truncation.
+ */
+ if (page->mapping)
+ mlock_vma_page(page);
+ unlock_page(page);
+ }
+ }
unlock:
pte_unmap_unlock(ptep, ptl);
out:
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