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authorAnton Arapov <anton@redhat.com>2012-09-12 09:18:33 +0200
committerAnton Arapov <anton@redhat.com>2012-09-12 09:19:26 +0200
commit985ef6b2108ed28ffd5f6630e1e0fce2e2a775f2 (patch)
treeeb9091ebd60e14eea65a9e6b5140f98d88e8a590 /mm/vmscan.c
parent1d44b6f3fcf6058fb7c960b7558766967e8028f7 (diff)
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fedora kernel: 021ce7bee3cfdcbf16da1256b2c9f40f7e9bbd9ev3.5.3-1
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c38
1 files changed, 35 insertions, 3 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 66e431060c0..f0f8ebbb224 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -720,9 +720,41 @@ static unsigned long shrink_page_list(struct list_head *page_list,
(PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
if (PageWriteback(page)) {
- nr_writeback++;
- unlock_page(page);
- goto keep;
+ /*
+ * memcg doesn't have any dirty pages throttling so we
+ * could easily OOM just because too many pages are in
+ * writeback and there is nothing else to reclaim.
+ *
+ * Check __GFP_IO, certainly because a loop driver
+ * thread 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.
+ */
+ if (global_reclaim(sc) ||
+ !PageReclaim(page) || !(sc->gfp_mask & __GFP_IO)) {
+ /*
+ * This is slightly racy - end_page_writeback()
+ * might have just cleared PageReclaim, then
+ * setting PageReclaim here end up interpreted
+ * as PageReadahead - but that does not matter
+ * enough to care. What we do want is for this
+ * page to have PageReclaim set next time memcg
+ * reclaim reaches the tests above, so it will
+ * then wait_on_page_writeback() to avoid OOM;
+ * and it's also appropriate in global reclaim.
+ */
+ SetPageReclaim(page);
+ nr_writeback++;
+ goto keep_locked;
+ }
+ wait_on_page_writeback(page);
}
references = page_check_references(page, sc);