From d950c9477d51f0cefc2ed3cf76e695d46af0d9c1 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Fri, 4 Sep 2015 15:47:35 -0700 Subject: mm: defer flush of writable TLB entries If a PTE is unmapped and it's dirty then it was writable recently. Due to deferred TLB flushing, it's best to assume a writable TLB cache entry exists. With that assumption, the TLB must be flushed before any IO can start or the page is freed to avoid lost writes or data corruption. This patch defers flushing of potentially writable TLBs as long as possible. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Dave Hansen Acked-by: Ingo Molnar Cc: Linus Torvalds Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'mm/vmscan.c') diff --git a/mm/vmscan.c b/mm/vmscan.c index 99ec00d6a5dd..b1139039122a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1098,7 +1098,12 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (!sc->may_writepage) goto keep_locked; - /* Page is dirty, try to write it out here */ + /* + * Page is dirty. Flush the TLB if a writable entry + * potentially exists to avoid CPU writes after IO + * starts and then write it out here. + */ + try_to_unmap_flush_dirty(); switch (pageout(page, mapping, sc)) { case PAGE_KEEP: goto keep_locked; -- cgit v1.2.3