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

Vineet Gupta
2013-05-29T12:56:41Z

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: Andrew Morton <akpm@linux-foundation.org>
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>
Cc: linux-mm@kvack.org
Cc: linux-arch@vger.kernel.org <linux-arch@vger.kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
---
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