linux-kernel - Re: [PATCHv6 1/1] mm: optimization on page allocation when CMA enabled

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Message-Id: <20231016153959.c218e1ae876426b9193eb294@linux-foundation.org>
Date:   Mon, 16 Oct 2023 15:39:59 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     "zhaoyang.huang" <zhaoyang.huang@...soc.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Zhaoyang Huang <huangzhaoyang@...il.com>,
        <steve.kang@...soc.com>
Subject: Re: [PATCHv6 1/1] mm: optimization on page allocation when CMA
 enabled

On Mon, 16 Oct 2023 15:12:45 +0800 "zhaoyang.huang" <zhaoyang.huang@...soc.com> wrote:

> From: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> 
> According to current CMA utilization policy, an alloc_pages(GFP_USER)
> could 'steal' UNMOVABLE & RECLAIMABLE page blocks via the help of
> CMA(pass zone_watermark_ok by counting CMA in but use U&R in rmqueue),
> which could lead to following alloc_pages(GFP_KERNEL) fail.
> Solving this by introducing second watermark checking for GFP_MOVABLE,
> which could have the allocation use CMA when proper.
> 
> -- Free_pages(30MB)
> |
> |
> -- WMARK_LOW(25MB)
> |
> -- Free_CMA(12MB)
> |
> |
> --
> 
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
> ---
> v6: update comments

The patch itself is identical to the v5 patch.  So either you meant
"update changelog" above or you sent the wrong diff?

Also, have we resolved any concerns regarding possible performance
impacts of this change?