linux-kernel - Re: [PATCH] arch_numa: Restore nid checks before registering a memblock with a node

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Message-ID: <87v7w6sa5s.wl-maz@kernel.org>
Date: Fri, 29 Nov 2024 08:42:55 +0000
From: Marc Zyngier <maz@...nel.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Zi Yan <ziy@...dia.com>,
	Dan Williams <dan.j.williams@...el.com>,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	stable@...r.kernel.org
Subject: Re: [PATCH] arch_numa: Restore nid checks before registering a memblock with a node

On Fri, 29 Nov 2024 08:24:16 +0000,
Mike Rapoport <rppt@...nel.org> wrote:
> 
> On Thu, Nov 28, 2024 at 04:52:14PM +0000, Marc Zyngier wrote:
> > Hi Mike,
> > 
> > On Thu, 28 Nov 2024 07:03:33 +0000,
> > Mike Rapoport <rppt@...nel.org> wrote:
> > > 
> > > Hi Marc,
> > > 
> > > > diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> > > > index e187016764265..5457248eb0811 100644
> > > > --- a/drivers/base/arch_numa.c
> > > > +++ b/drivers/base/arch_numa.c
> > > > @@ -207,7 +207,21 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
> > > >  static int __init numa_register_nodes(void)
> > > >  {
> > > >  	int nid;
> > > > -
> > > > +	struct memblock_region *mblk;
> > > > +
> > > > +	/* Check that valid nid is set to memblks */
> > > > +	for_each_mem_region(mblk) {
> > > > +		int mblk_nid = memblock_get_region_node(mblk);
> > > > +		phys_addr_t start = mblk->base;
> > > > +		phys_addr_t end = mblk->base + mblk->size - 1;
> > > > +
> > > > +		if (mblk_nid == NUMA_NO_NODE || mblk_nid >= MAX_NUMNODES) {
> > > > +			pr_warn("Warning: invalid memblk node %d [mem %pap-%pap]\n",
> > > > +				mblk_nid, &start, &end);
> > > > +			return -EINVAL;
> > > > +		}
> > > 
> > > We have memblock_validate_numa_coverage() that checks that amount of memory
> > > with unset node id is less than a threshold. The loop here can be replaced
> > > with something like
> > > 
> > > 	if (!memblock_validate_numa_coverage(0))
> > > 		return -EINVAL;
> > 
> > Unfortunately, that doesn't seem to result in something that works
> > (relevant extract only):
> > 
> > [    0.000000] NUMA: no nodes coverage for 9MB of 65516MB RAM
> > [    0.000000] NUMA: Faking a node at [mem 0x0000000000500000-0x0000000fff0fffff]
> > [    0.000000] NUMA: no nodes coverage for 0MB of 65516MB RAM
> > [    0.000000] Unable to handle kernel paging request at virtual address 0000000000001d40
> > 
> > Any idea?
> 
> With 0 as the threshold the validation fails for the fake node, but it
> should be fine with memblock_validate_numa_coverage(1)

Huh, subtle. This indeed seems to work. I'll respin the patch next week.

Thanks for your help,

	M.

-- 
Without deviation from the norm, progress is not possible.