Kernel bump from 4.1.3-rt to 4.1.7-rt.

[kvmfornfv.git] / kernel / mm / vmscan.c

diff --git a/kernel/mm/vmscan.c b/kernel/mm/vmscan.c
index 5e8eadd..0d024fc 100644 (file)
--- a/kernel/mm/vmscan.c
+++ b/kernel/mm/vmscan.c
@@ -937,21 +937,17 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                 *
                 * 2) Global reclaim encounters a page, memcg encounters a
                 *    page that is not marked for immediate reclaim or
-                *    the caller does not have __GFP_IO. In this case mark
+                *    the caller does not have __GFP_FS (or __GFP_IO if it's
+                *    simply going to swap, not to fs). In this case mark
                 *    the page for immediate reclaim and continue scanning.
                 *
-                *    __GFP_IO is checked  because a loop driver thread might
+                *    Require may_enter_fs because we would wait on fs, which
+                *    may not have submitted IO yet. And the loop driver might
                 *    enter reclaim, and deadlock if it waits on a page for
                 *    which it is needed to do the write (loop masks off
                 *    __GFP_IO|__GFP_FS for this reason); but more thought
                 *    would probably show more reasons.
                 *
-                *    Don't require __GFP_FS, since we're not going into the
-                *    FS, just waiting on its writeback completion. Worryingly,
-                *    ext4 gfs2 and xfs allocate pages with
-                *    grab_cache_page_write_begin(,,AOP_FLAG_NOFS), so testing
-                *    may_enter_fs here is liable to OOM on them.
-                *
                 * 3) memcg encounters a page that is not already marked
                 *    PageReclaim. memcg does not have any dirty pages
                 *    throttling so we could easily OOM just because too many
@@ -968,7 +964,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 
                        /* Case 2 above */
                        } else if (global_reclaim(sc) ||
-                           !PageReclaim(page) || !(sc->gfp_mask & __GFP_IO)) {
+                           !PageReclaim(page) || !may_enter_fs) {
                                /*
                                 * This is slightly racy - end_page_writeback()
                                 * might have just cleared PageReclaim, then