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Date:   Mon, 2 Nov 2020 16:03:57 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Alex Shi <alex.shi@linux.alibaba.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>, akpm@linux-foundation.org,
        mgorman@techsingularity.net, tj@kernel.org, hughd@google.com,
        khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com,
        lkp@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        cgroups@vger.kernel.org, shakeelb@google.com,
        iamjoonsoo.kim@lge.com, richard.weiyang@gmail.com,
        kirill@shutemov.name, alexander.duyck@gmail.com,
        rong.a.chen@intel.com, mhocko@suse.com, vdavydov.dev@gmail.com,
        shy828301@gmail.com
Subject: Re: [PATCH v20 04/20] mm/thp: use head for head page in
 lru_add_page_tail
Message-ID: <20201102160357.GP27442@casper.infradead.org>
References: <1603968305-8026-1-git-send-email-alex.shi@linux.alibaba.com>
 <1603968305-8026-5-git-send-email-alex.shi@linux.alibaba.com>
 <20201029135047.GE599825@cmpxchg.org>
 <06a5b7d8-bbf2-51b7-1352-2b630186e15f@linux.alibaba.com>
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Precedence: bulk

On Fri, Oct 30, 2020 at 10:46:54AM +0800, Alex Shi wrote:
> -static void lru_add_page_tail(struct page *page, struct page *page_tail,
> +static void lru_add_page_tail(struct page *head, struct page *tail,
>  		struct lruvec *lruvec, struct list_head *list)
>  {
> -	VM_BUG_ON_PAGE(!PageHead(page), page);
> -	VM_BUG_ON_PAGE(PageCompound(page_tail), page);
> -	VM_BUG_ON_PAGE(PageLRU(page_tail), page);
> +	VM_BUG_ON_PAGE(!PageHead(head), head);
> +	VM_BUG_ON_PAGE(PageCompound(tail), head);
> +	VM_BUG_ON_PAGE(PageLRU(tail), head);

These last two should surely have been
	VM_BUG_ON_PAGE(PageCompound(tail), tail);
	VM_BUG_ON_PAGE(PageLRU(tail), tail);

Also, what do people think about converting these to VM_BUG_ON_PGFLAGS?

Either way:

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>