linux-kernel - Re: [PATCH v5 02/11] mm/mempolicy: introduce MPOL_WEIGHTED

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Date: Tue, 26 Dec 2023 06:32:54 -0500
From: Gregory Price <gregory.price@...verge.com>
To: "Huang, Ying" <ying.huang@...el.com>
Cc: Gregory Price <gourry.memverge@...il.com>, linux-mm@...ck.org,
	linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org,
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	sthanneeru@...ron.com, emirakhur@...ron.com, Hasan.Maruf@....com,
	seungjun.ha@...sung.com,
	Srinivasulu Thanneeru <sthanneeru.opensrc@...ron.com>
Subject: Re: [PATCH v5 02/11] mm/mempolicy: introduce
 MPOL_WEIGHTED_INTERLEAVE for weighted interleaving

On Tue, Dec 26, 2023 at 02:01:57AM -0500, Gregory Price wrote:
> On Wed, Dec 27, 2023 at 04:32:37PM +0800, Huang, Ying wrote:
> > Gregory Price <gourry.memverge@...il.com> writes:
> 
> Barrier is to stabilize nodemask on the stack, but yes i'll carry the
> comment from interleave_nid into this barrier as well.
> 
> > > +
> > > +	/* first ensure we have a valid nodemask */
> > > +	nid = first_node(nodemask);
> > > +	if (nid == MAX_NUMNODES)
> > > +		return nid;
> > 
> > It appears that this isn't necessary, because we can check whether
> > weight_total == 0 after the next loop.
> > 
> 
> fair, will snip.
> 

Follow up - this is only possible if the nodemask is invalid / has no
nodes, so it's better to check for this explicitly.  If nodemask is
valid, then it's not possible to have a weight_total of 0, because
weights cannot be 0.

~Gregory