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From: Johannes Weiner <hannes@cmpxchg.org>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	cgroups@vger.kernel.org, Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>
Subject: Re: [PATCH RFC] mm/memcontrol: reclaim severe usage over high limit in get_user_pages loop
Date: Mon, 29 Jul 2019 11:49:52 -0400	[thread overview]
Message-ID: <20190729154952.GC21958@cmpxchg.org> (raw)
In-Reply-To: <156431697805.3170.6377599347542228221.stgit@buzz>

On Sun, Jul 28, 2019 at 03:29:38PM +0300, Konstantin Khlebnikov wrote:
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -847,8 +847,11 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
>  			ret = -ERESTARTSYS;
>  			goto out;
>  		}
> -		cond_resched();
>  
> +		/* Reclaim memory over high limit before stocking too much */
> +		mem_cgroup_handle_over_high(true);

I'd rather this remained part of the try_charge() call. The code
comment in try_charge says this:

	 * We can perform reclaim here if __GFP_RECLAIM but let's
	 * always punt for simplicity and so that GFP_KERNEL can
	 * consistently be used during reclaim.

The simplicity argument doesn't hold true anymore once we have to add
manual calls into allocation sites. We should instead fix try_charge()
to do synchronous reclaim for __GFP_RECLAIM and only punt to userspace
return when actually needed.


  parent reply	other threads:[~2019-07-29 15:50 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-28 12:29 Konstantin Khlebnikov
2019-07-29  9:17 ` Michal Hocko
2019-07-29  9:40   ` Konstantin Khlebnikov
2019-07-29 10:33     ` Michal Hocko
2019-07-29 11:24       ` Konstantin Khlebnikov
2019-07-29 17:28       ` Yang Shi
2019-07-29 18:48         ` Michal Hocko
2019-08-01 21:00           ` Yang Shi
2019-08-02  9:35             ` Michal Hocko
2019-08-02 18:56               ` Yang Shi
2019-08-05 14:32                 ` Michal Hocko
2019-08-05 19:24                   ` Shakeel Butt
2019-08-06  3:28                   ` Yang Shi
2019-08-06  7:05                     ` Michal Hocko
2019-07-29 15:49 ` Johannes Weiner [this message]
2019-07-29 18:55   ` Michal Hocko
2019-08-02  9:40     ` Michal Hocko
2019-08-02 10:01       ` Konstantin Khlebnikov
2019-08-02 11:44         ` Michal Hocko
2019-08-06  7:07           ` Michal Hocko
2019-08-06  7:19             ` Konstantin Khlebnikov
2019-08-06  7:36               ` Michal Hocko

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