Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	qiuxishi@huawei.com, Igor Mammedov <imammedo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory
Date: Fri, 8 Sep 2017 19:27:28 +0200
Message-ID: <d88f141b-f782-4352-f2b0-00639352097e@suse.cz> (raw)
In-Reply-To: <20170904082148.23131-3-mhocko@kernel.org>

On 09/04/2017 10:21 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> We have a hardcoded 120s timeout after which the memory offline fails
> basically since the hot remove has been introduced. This is essentially
> a policy implemented in the kernel. Moreover there is no way to adjust
> the timeout and so we are sometimes facing memory offline failures if
> the system is under a heavy memory pressure or very intensive CPU
> workload on large machines.
> 
> It is not very clear what purpose the timeout actually serves. The
> offline operation is interruptible by a signal so if userspace wants
> some timeout based termination this can be done trivially by sending a
> signal.
> 
> If there is a strong usecase to do this from the kernel then we should
> do it properly and have a it tunable from the userspace with the timeout
> disabled by default along with the explanation who uses it and for what
> purporse.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Makes sense to me.

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/memory_hotplug.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index c9dcbe6d2ac6..b8a85c11360e 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1593,9 +1593,9 @@ static void node_states_clear_node(int node, struct memory_notify *arg)
>  }
>  
>  static int __ref __offline_pages(unsigned long start_pfn,
> -		  unsigned long end_pfn, unsigned long timeout)
> +		  unsigned long end_pfn)
>  {
> -	unsigned long pfn, nr_pages, expire;
> +	unsigned long pfn, nr_pages;
>  	long offlined_pages;
>  	int ret, node;
>  	unsigned long flags;
> @@ -1633,12 +1633,8 @@ static int __ref __offline_pages(unsigned long start_pfn,
>  		goto failed_removal;
>  
>  	pfn = start_pfn;
> -	expire = jiffies + timeout;
>  repeat:
>  	/* start memory hot removal */
> -	ret = -EBUSY;
> -	if (time_after(jiffies, expire))
> -		goto failed_removal;
>  	ret = -EINTR;
>  	if (signal_pending(current))
>  		goto failed_removal;
> @@ -1711,7 +1707,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
>  /* Must be protected by mem_hotplug_begin() or a device_lock */
>  int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
>  {
> -	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
> +	return __offline_pages(start_pfn, start_pfn + nr_pages);
>  }
>  #endif /* CONFIG_MEMORY_HOTREMOVE */
>  
> 

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  parent reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-04  8:21 [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-04  8:21 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko
2017-09-05  6:29   ` Anshuman Khandual
2017-09-05  7:13     ` Michal Hocko
2017-09-08 17:26   ` Vlastimil Babka
2017-09-11  8:17     ` Michal Hocko
2017-09-13 11:41       ` Vlastimil Babka
2017-09-13 12:10         ` Michal Hocko
2017-09-13 12:14           ` Michal Hocko
2017-09-13 12:19             ` Vlastimil Babka
2017-09-13 12:32               ` Michal Hocko
2017-09-04  8:21 ` [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko
2017-09-04  8:58   ` Xishi Qiu
2017-09-04  9:01     ` Michal Hocko
2017-09-04  9:05       ` Xishi Qiu
2017-09-04  9:15         ` Michal Hocko
2017-09-05  5:46           ` Anshuman Khandual
2017-09-05  7:23             ` Michal Hocko
2017-09-05  8:54               ` Anshuman Khandual
2017-09-08 17:27   ` Vlastimil Babka [this message]
2017-09-18  7:08 [PATCH v2 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-18  7:08 ` [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d88f141b-f782-4352-f2b0-00639352097e@suse.cz \
    --to=vbabka@suse.cz \
    --cc=akpm@linux-foundation.org \
    --cc=arbab@linux.vnet.ibm.com \
    --cc=imammedo@redhat.com \
    --cc=kamezawa.hiroyu@jp.fujitsu.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=mhocko@suse.com \
    --cc=qiuxishi@huawei.com \
    --cc=vkuznets@redhat.com \
    --cc=yasu.isimatu@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git