linux-kernel - Re: [PATCH v4 1/2] mm/hmm: make full use of walk_page

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Message-ID: <20191112151856.GB12550@lst.de>
Date:   Tue, 12 Nov 2019 16:18:56 +0100
From:   Christoph Hellwig <hch@....de>
To:     Ralph Campbell <rcampbell@...dia.com>
Cc:     Jerome Glisse <jglisse@...hat.com>,
        John Hubbard <jhubbard@...dia.com>,
        Christoph Hellwig <hch@....de>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Shuah Khan <shuah@...nel.org>, linux-rdma@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 1/2] mm/hmm: make full use of walk_page_range()

Looks good,

Reviewed-by: Christoph Hellwig <hch@....de>

Although we could clean this up a tidbit more by removing the start
variable:

diff --git a/mm/hmm.c b/mm/hmm.c
index d4984a08ed9b..b5b1ed646c2f 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -667,10 +667,9 @@ static const struct mm_walk_ops hmm_walk_ops = {
  */
 long hmm_range_fault(struct hmm_range *range, unsigned int flags)
 {
-	unsigned long start = range->start;
 	struct hmm_vma_walk hmm_vma_walk = {
 		.range = range,
-		.last = start,
+		.last = range->start,
 		.flags = flags,
 	};
 	struct mm_struct *mm = range->notifier->mm;
@@ -682,9 +681,8 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
 		/* If range is no longer valid force retry. */
 		if (mmu_range_check_retry(range->notifier, range->notifier_seq))
 			return -EBUSY;
-		ret = walk_page_range(mm, start, range->end, &hmm_walk_ops,
-				      &hmm_vma_walk);
-		start = hmm_vma_walk.last;
+		ret = walk_page_range(mm, hmm_vma_walk.last, range->end,
+				      &hmm_walk_ops, &hmm_vma_walk);
 	} while (ret == -EBUSY);
 
 	if (ret)