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b=VtQ6Hw6QjRd5uPS7YgtsbzrPNJlC5dJ3ukdGd7UZNSPTXE7XJbgLIdr9XRhiBlxuX yh91BKP4A9zDk7sM+WN4RIrZuZ7GL7FWf1ai5fN6BYkKvOZxAXXUqnnQmppqJHtL9/ 3HAil7y1GX+McNb6PdHpVYlKSoDtfs3MQ4yYzdlfMOc1IAz0VA7mhjQGphnzakT3yE AxPc0QD87Ksdrljtets3vrOxy80YbJ3SEWr9w/IMulVXxQ0jY9tnXrOhzEaXP4F8zu cyYNS6TIQ7LHfme0J4GZR7PdAQTkZ2FOdApzQioRLbnQ2iK7rHW5lJurFmBcT9GolA V9nlXZvPRcZ4w== Date: Thu, 30 Jul 2026 09:58:01 +0300 From: Mike Rapoport To: Andrew Morton Cc: Sang-Heon Jeon , linux-mm@kvack.org Subject: Re: [PATCH] mm/mm_init: remove unnecessary initialization of pgdat->per_cpu_nodestats Message-ID: References: <20260729155143.177790-1-ekffu200098@gmail.com> <20260729132745.9d42a13e614be2e18c5988ba@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260729132745.9d42a13e614be2e18c5988ba@linux-foundation.org> X-Rspamd-Queue-Id: 1EFD7180002 X-Rspam-User: X-Stat-Signature: izqi4gd3catsxgf9jrohjdmf4zxje7xq X-Rspamd-Server: rspam04 X-HE-Tag: 1785394686-892087 X-HE-Meta: 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 n38ygRMv TLvJGNEw76/z5L+7sXiTdwhKl4xspW68QGGRc/kO+lTyHWcaARR4/AITdnYGCcWjgElnRmpug1kxrqWT3iFXN/S+JLeV4RNUWkqxsCgB609Nt4xjHUcKBbP3f8kFoAPOMQxPn8HjbU81J7hvRRfopaR/E3FSIkQhnnMJyRz6FiE9lvogpu2Ed9S2RmJNdn3RFHB6svdflcx1JuQ1dmcY43fnlDk0XL47TpQ4mBjWbnJOZauHigN7VNq2MkvxW0a80nP+ZWXmhExHwSCblSFzFvWwBU40E/dM9J3uoUD/nAlii8uZKC6kRDrj3Atjh+pmizik6 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 29, 2026 at 01:27:45PM -0700, Andrew Morton wrote: > On Thu, 30 Jul 2026 00:51:15 +0900 Sang-Heon Jeon wrote: > > > free_area_init_node() sets pgdat->per_cpu_nodestats to NULL and later > > calls free_area_init_core(), which unconditionally overwrites it with > > &boot_nodestats. Nothing reads the field in between, so the store has > > no effect. > > > > Remove unnecessary initialization. No functional change. > > > > ... > > > > --- a/mm/mm_init.c > > +++ b/mm/mm_init.c > > @@ -1722,7 +1722,6 @@ static void __init free_area_init_node(int nid) > > > > pgdat->node_id = nid; > > pgdat->node_start_pfn = start_pfn; > > - pgdat->per_cpu_nodestats = NULL; > > > > if (start_pfn != end_pfn) { > > pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid, > > Looks OK, thanks. Although this statement is "free" in __init code and > its removal does make the code that bit harder to follow. Heh, it's already not that easy to follow :) We initialize a few fields in pgdat, then setup node and its zone sizes, then return to initialization of the rest of pgdat internals. It feels like we need a larger cleanup there, and this patch wouldn't really move a needle. > Possibly *pgdat was zeroed out anyway, I got bored figuring that out. > The memblock_alloc_range_nid() kerneldoc is silent on the state of the > returned memory but I spy a kzalloc_node() in there. memblock_alloc_range_nid() does not zero the memory, unless inappropriately called after slab_is_available(). But alloc_node_data() that allocates pgdat's does :) -- Sincerely yours, Mike.