From: David Rientjes <rientjes@google.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Christopher Lameter <cl@linux.com>,
Sachin Sant <sachinp@linux.vnet.ibm.com>,
Pekka Enberg <penberg@kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [5.6.0-rc2-next-20200218/powerpc] Boot failure on POWER9
Date: Wed, 26 Feb 2020 12:31:56 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.21.2002261228060.208847@chino.kir.corp.google.com> (raw)
In-Reply-To: <20200226190147.GR3771@dhcp22.suse.cz>
On Wed, 26 Feb 2020, Michal Hocko wrote:
> On Wed 26-02-20 18:44:13, Cristopher Lameter wrote:
> > On Wed, 26 Feb 2020, Michal Hocko wrote:
> >
> > > Besides that kmalloc_node shouldn't really have an implicit GFP_THISNODE
> > > semantic right? At least I do not see anything like that documented
> > > anywhere.
> >
> > Kmalloc_node does not support memory policies etc. Only kmalloc does.
> > kmalloc_node is mostly used by subsystems that have determined the active
> > nodes and want a targeted allocation on those nodes.
>
> I am sorry but I have hard time to follow your responses here. They open
> more questions than they answer for me. The primary point here is that
> kmalloc_node on a memory less node blows up and panics the kernel. I
> strongly believe this is a bug. We cannot really make all callers of
> kmalloc_node and co. to be hotplug aware.
>
> Another question is the semantic of kmalloc_node when the node cannot
> satisfy the request. I have always thought that the allocation would
> simply fall back to any other node unless __GFP_THISNODE is explicitly
> specified.
>
Am I right in classifying this as a trade-off between an
unlikely(!node_state(nid, N_MEMORY)) directly in kmalloc_node() vs fixing
up a caller passing a memoryless nid?
Seems like we wouldn't want to penalize kmalloc_node() for making such a
check for 99.99% of allocators that don't need it and would rather do a
node_to_mem_node(nid) or numa_mem_id() in the caller?
next prev parent reply other threads:[~2020-02-26 20:32 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 10:45 [5.6.0-rc2-next-20200218/powerpc] Boot failure on POWER9 Sachin Sant
2020-02-18 10:50 ` Kirill Tkhai
2020-02-18 11:01 ` Kirill Tkhai
2020-02-18 11:35 ` Kirill Tkhai
2020-02-18 11:40 ` Sachin Sant
2020-02-18 11:55 ` Michal Hocko
2020-02-18 14:00 ` Sachin Sant
2020-02-18 14:26 ` Michal Hocko
2020-02-18 15:11 ` Sachin Sant
2020-02-18 15:24 ` Michal Hocko
2020-02-22 3:38 ` Christopher Lameter
2020-02-24 8:58 ` Michal Hocko
2020-02-26 18:25 ` Christopher Lameter
2020-02-26 18:41 ` Michal Hocko
2020-02-26 18:44 ` Christopher Lameter
2020-02-26 19:01 ` Michal Hocko
2020-02-26 20:31 ` David Rientjes [this message]
2020-02-26 20:52 ` Michal Hocko
2020-02-26 21:45 ` Vlastimil Babka
2020-02-26 22:29 ` Vlastimil Babka
2020-02-27 12:12 ` Michal Hocko
2020-02-27 16:00 ` Sachin Sant
2020-02-27 16:16 ` Vlastimil Babka
2020-02-27 18:26 ` Michal Hocko
2020-03-10 15:01 ` Michal Hocko
2020-03-12 12:18 ` Michael Ellerman
2020-03-12 16:51 ` Sachin Sant
2020-03-13 10:48 ` Michael Ellerman
2020-03-13 11:12 ` Srikar Dronamraju
2020-03-13 11:35 ` Vlastimil Babka
2020-03-14 8:10 ` Sachin Sant
2020-02-27 12:02 ` Michal Hocko
2020-02-18 11:38 ` Sachin Sant
2020-02-18 11:53 ` Kirill Tkhai
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