[PATCH] mm: Fix the TLB range flushed when __tlb_remove_page() runs out of slots

[Vineet Gupta]

zap_pte_range loops from @addr to @end. In the middle, if it runs out of
batching slots, TLB entries needs to be flushed for @start to @interim,
NOT @interim to @end.

Since ARC port doesn't use page free batching I can't test it myself but
this seems like the right thing to do.
Observed this when working on a fix for the issue at thread:
	http://www.spinics.net/lists/linux-arch/msg21736.html

Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx <linux-arch@xxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
---
 mm/memory.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 6dc1882..d9d5fd9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1110,6 +1110,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	spinlock_t *ptl;
 	pte_t *start_pte;
 	pte_t *pte;
+	unsigned long range_start = addr;
 
 again:
 	init_rss_vec(rss);
@@ -1215,12 +1216,14 @@ again:
 		force_flush = 0;
 
 #ifdef HAVE_GENERIC_MMU_GATHER
-		tlb->start = addr;
-		tlb->end = end;
+		tlb->start = range_start;
+		tlb->end = addr;
 #endif
 		tlb_flush_mmu(tlb);
-		if (addr != end)
+		if (addr != end) {
+			range_start = addr;
 			goto again;
+		}
 	}
 
 	return addr;
-- 
1.7.10.4

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