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

Vineet Gupta
2013-05-30T05:02:36Z

[+alex.shi@intel.com]

On 05/29/2013 06:26 PM, Vineet Gupta wrote:
> 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;
>