mm: fix the TLB range flushed when __tlb_remove_page() runs out of slots

commit e6c495a96ce02574e765d5140039a64c8d4e8c9e upstream.

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@synopsys.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index 61a262b..5e50800 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1101,6 +1101,7 @@ 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);
@@ -1206,12 +1207,14 @@ 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;