linux-kernel - Re: [PATCH] bdi flusher should not be throttled here when it fall into buddy slow path

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Date:   Tue, 18 Oct 2016 17:34:41 +0800
From:   "Hillf Danton" <hillf.zj@...baba-inc.com>
To:     <zhouxianrong@...wei.com>, <linux-mm@...ck.org>
Cc:     <linux-kernel@...r.kernel.org>, <akpm@...ux-foundation.org>,
        <viro@...iv.linux.org.uk>, <mingo@...hat.com>,
        <peterz@...radead.org>, <hannes@...xchg.org>,
        <mgorman@...hsingularity.net>, <vbabka@...e.cz>, <mhocko@...e.com>,
        <vdavydov.dev@...il.com>, <minchan@...nel.org>, <riel@...hat.com>,
        <zhouxiyu@...wei.com>, <zhangshiming5@...wei.com>,
        <won.ho.park@...wei.com>, <tuxiaobing@...wei.com>
Subject: Re: [PATCH] bdi flusher should not be throttled here when it fall into buddy slow path

> @@ -1908,7 +1908,7 @@ void wb_workfn(struct work_struct *work)
>  	long pages_written;
> 
>  	set_worker_desc("flush-%s", dev_name(wb->bdi->dev));
> -	current->flags |= PF_SWAPWRITE;

If flags carries PF_LESS_THROTTLE before modified, then you 
have to restore it. 

> +	current->flags |= (PF_SWAPWRITE | PF_BDI_FLUSHER | PF_LESS_THROTTLE);
> 
>  	if (likely(!current_is_workqueue_rescuer() ||
>  		   !test_bit(WB_registered, &wb->state))) {
> @@ -1938,7 +1938,7 @@ void wb_workfn(struct work_struct *work)
>  	else if (wb_has_dirty_io(wb) && dirty_writeback_interval)
>  		wb_wakeup_delayed(wb);
> 
> -	current->flags &= ~PF_SWAPWRITE;
> +	current->flags &= ~(PF_SWAPWRITE | PF_BDI_FLUSHER | PF_LESS_THROTTLE);
>  }
> 
thanks
Hillf