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Date:   Thu, 13 Oct 2022 17:04:19 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Yu Zhao <yuzhao@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Andi Kleen <ak@linux.intel.com>,
        Aneesh Kumar <aneesh.kumar@linux.ibm.com>,
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Subject: Re: [PATCH v14 08/14] mm: multi-gen LRU: support page table walks
Message-ID: <Y0go8wWtdcyH1+Ch@hirez.programming.kicks-ass.net>
References: <20220815071332.627393-1-yuzhao@google.com>
 <20220815071332.627393-9-yuzhao@google.com>
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On Mon, Aug 15, 2022 at 01:13:27AM -0600, Yu Zhao wrote:
> +	for (i = pmd_index(start), addr = start; addr != end; i++, addr = next) {
> +		pmd_t val = pmd_read_atomic(pmd + i);
> +
> +		/* for pmd_read_atomic() */
> +		barrier();

Please clarify the above. This is an entirely inadequate ordering
comment.

> +
> +		next = pmd_addr_end(addr, end);