linux-kernel - Re: [PATCH v2] ext4: fix prefetchw of NULL page

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Message-ID: <20190407155521.GL18897@mit.edu>
Date:   Sun, 7 Apr 2019 11:55:21 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Liu Xiang <liu.xiang6@....com.cn>
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        adilger.kernel@...ger.ca, liuxiang_1999@....com
Subject: Re: [PATCH v2] ext4: fix prefetchw of NULL page

On Sun, Mar 31, 2019 at 04:11:34PM +0800, Liu Xiang wrote:
> In ext4_mpage_readpages(), if the parameter pages is not NULL, another
> parameter page is NULL. At the first time prefetchw(&page->flags)
> works on NULL. From second time, prefetchw(&page->flags) always works on
> the last consumed page. This might do little improvment for handling
> current page. So prefetchw() should be called while the page pointer
> has just been updated.

Thanks, applied.

					- Ted