linux-kernel - Re: [PATCH] memblock: update numa node of memblk reserved type

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Message-ID: <20230524153344.GM4967@kernel.org>
Date:   Wed, 24 May 2023 18:33:44 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        20230519105321.333-1-ssawgyw@...il.com,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, tsahu@...ux.ibm.com,
        ssawgyw@...il.com
Subject: Re: [PATCH] memblock: update numa node of memblk reserved type

On Wed, May 24, 2023 at 02:47:26PM +0800, Kefeng Wang wrote:
> 
> On 2023/5/24 12:59, Anshuman Khandual wrote:
> > 
> > On 5/23/23 17:27, Kefeng Wang wrote:
> > > The numa node of memblk reserved type is wrong, it could update
> > > according to the numa node information from memblk memory type,
> > > let's fix it.
> > 
> > Indeed it's wrong at present and can be verified from sysfs file
> > (/sys/kernel/debug/memblock/reserved) accessed in user space.
> 
> Yes, both memblock_dump() and sysfs show wrong value.
> > 
> > > 
> > > Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> > > ---
> > >   mm/memblock.c | 25 +++++++++++++++++++++++++
> > >   1 file changed, 25 insertions(+)
> > > 
> > > diff --git a/mm/memblock.c b/mm/memblock.c
> > > index a50447d970ef..45a0781cda31 100644
> > > --- a/mm/memblock.c
> > > +++ b/mm/memblock.c
> > > @@ -1922,6 +1922,28 @@ phys_addr_t __init_memblock memblock_get_current_limit(void)
> > >   	return memblock.current_limit;
> > >   }
> > > +static void __init_memblock memblock_reserved_update_node(void)
> > > +{
> > > +	struct memblock_region *rgn;
> > > +	phys_addr_t base, end, size;
> > > +	int ret;
> > > +
> > > +	if (!IS_ENABLED(CONFIG_NUMA))
> > > +		return;
> > > +
> > > +	for_each_mem_region(rgn) {
> > > +		base = rgn->base;
> > > +		size = rgn->size;
> > > +		end = base + size - 1;
> > > +
> > > +		ret = memblock_set_node(base, size, &memblock.reserved,
> > > +					memblock_get_region_node(rgn));
> > > +		if (ret)
> > > +			pr_err("memblock: Failed to update reserved [%pa-%pa] node",
> > > +			       &base, &end);
> > > +	}
> > > +}
> > > +
> > >   static void __init_memblock memblock_dump(struct memblock_type *type)
> > >   {
> > >   	phys_addr_t base, end, size;
> > > @@ -1955,6 +1977,7 @@ static void __init_memblock __memblock_dump_all(void)
> > >   		&memblock.memory.total_size,
> > >   		&memblock.reserved.total_size);
> > > +	memblock_reserved_update_node();
> > 
> > __memblock_dump_all() gets called only when memblock_debug is enabled.
> > This helper should be called directly inside memblock_dump_all() right
> > at the beginning, regardless of memblock_debug.
> 
> This is my first though, but I found there are still many memblock_alloc and
> memblock_reserve after memblock_dump_all(), so I update it twice,
> 
> 1) __memblock_dump_all()
> 2) memblock_debug_show()
> 
> and without the above two interface, no one care about the reserved node
> info, so I put memblock_reserved_update_node into __memblock_dump_all().
 
We don't care about the reserved node info and __memblock_dump_all()
actually does not print node info for reserved regions unless somebody
explicitly sets the node id on a reserved memory.

So instead of updating reserved memory node info I'd rather avoid printing
it in debugfs.
 
> > >   #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
> > > @@ -2196,6 +2219,8 @@ static int memblock_debug_show(struct seq_file *m, void *private)
> > >   	unsigned int count = ARRAY_SIZE(flagname);
> > >   	phys_addr_t end;
> > > +	memblock_reserved_update_node();
> > > +
> > 
> 
> > This is redundant, should be dropped. Reserved memblock ranges need not
> > be scanned, each time the sysfs file is accessed from user space.
> 
> Yes, it's better to move it into memblock_init_debugfs(),
> which only called once.
> 
> 
> 

-- 
Sincerely yours,
Mike.