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Date:   Mon, 10 Feb 2020 17:10:21 -0800
From:   Matthew Wilcox <willy@infradead.org>
To:     Minchan Kim <minchan@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-mm <linux-mm@kvack.org>,
        Josef Bacik <josef@toxicpanda.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: fix long time stall from mm_populate
Message-ID: <20200211011021.GP8731@bombadil.infradead.org>
References: <20200211001958.170261-1-minchan@kernel.org>
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On Mon, Feb 10, 2020 at 04:19:58PM -0800, Minchan Kim wrote:
>       filemap_fault
>         find a page form page(PG_uptodate|PG_readahead|PG_writeback)

Uh ... That shouldn't be possible.

        /*
         * Same bit is used for PG_readahead and PG_reclaim.
         */
        if (PageWriteback(page))
                return;

        ClearPageReadahead(page);