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b=KH/VEjJW7x+1+vKIiNbh0wXM5dynTbaDtAmmor/UYdeDtWZsO0JhjFxH0r2Jv9iAH AVYVKb5RryzAVIDpfzpzeHwRyawkDGzjYH5ACk2+azwdxI2Y2UcEcIcJS7TE4v/wQp vmmhqnPKxJptPL18YXDTx+gsAzIiDx3eTZiu9PSNUybGtPn6R/2QEbK00Vr9TY/1X+ ELOfZVnE14I+IbT3OuVddeqtDxMtu3ul7LDS3T2XjBayIhqXAM5hsLUlw0k7H6TFei yLoUfn4gVVegauS7xq1/i8CAJUwgW3pMXb/YH+amIvetlydimO6CI1Vd3hMYgXe/uZ ngFpcHqpzmVBA== Date: Mon, 20 Apr 2026 09:49:11 +0300 From: Mike Rapoport To: Sang-Heon Jeon Cc: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org Subject: Re: [PATCH] mm/sparse: remove unnecessary NULL check before allocating mem_section Message-ID: References: <20260419144225.2875654-1-ekffu200098@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260419144225.2875654-1-ekffu200098@gmail.com> X-Stat-Signature: ppo7t1fcjkebgdaqjiq1cxawos3j4g8k X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9038140008 X-HE-Tag: 1776667758-961666 X-HE-Meta: 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 RyKEKE6f VnqnAlR9LjdxRdexPxiHIYs0+WQCWx+FGJtuYv/axvD/Vn9sdHIyNmCXTr7/JMDcUBjZ+dofO8kHoo/0di+L/9mJVV1WPbAcw4f2iki7j4Nn//j5AMR0idSRsRVEdj6V2/S7vRRD4O6cNVbJMhVvaDjaC4y4NSqZj+OAqiAJjuDk8NcSoFaI+WP5zEtkbRFmDKrmFVXobjrxdcVznA6/haMKvtGqNbb80rcYp0eqPoTW94fwbrhXfKHvWr0WnslmxpLSACRki5cRc1SXlXYZ7Zn7WFWSA77jLZuvcAXmQbSayzU5O0ss9aQcFaC6vyy+evMg+f/tUetjCcDjX7izo0cPwRR+RnaH4g/mZ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, On Sun, Apr 19, 2026 at 11:42:25PM +0900, Sang-Heon Jeon wrote: > Commit 850ed20539a4 ("mm: move array mem_section init code out > of memory_present()") moved mem_section allocation logic > into memblocks_present(). > > Before that move, memory_present() could be called multiple times, so > unlikely() matched the common case, where most calls found mem_section > already allocated. > > After that move, memblocks_present() is called exactly once from > sparse_init(). Under CONFIG_SPARSEMEM_EXTREME, mem_section is always > NULL when it is called. > > So remove unnecessary NULL check before allocating mem_section. No > functional change. > > Signed-off-by: Sang-Heon Jeon Acked-by: Mike Rapoport (Microsoft) > --- > Hello, > > While looking into boot information, I found a minor enhancement point. > If I misunderstood anything, please feel free to let me know. I would say it's more a cleanup than enhancement :) > Thank you for taking valuable time to review this work. > > Best Regards, > Sang-Heon Jeon > --- > mm/sparse.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index effdac6b0ab1..e13f9f5fa090 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -201,13 +201,11 @@ static void __init memblocks_present(void) > int i, nid; > > #ifdef CONFIG_SPARSEMEM_EXTREME > - if (unlikely(!mem_section)) { > - unsigned long size, align; > + unsigned long size, align; > > - size = sizeof(struct mem_section *) * NR_SECTION_ROOTS; > - align = 1 << (INTERNODE_CACHE_SHIFT); > - mem_section = memblock_alloc_or_panic(size, align); > - } > + size = sizeof(struct mem_section *) * NR_SECTION_ROOTS; > + align = 1 << (INTERNODE_CACHE_SHIFT); > + mem_section = memblock_alloc_or_panic(size, align); > #endif > > for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) > -- > 2.43.0 > -- Sincerely yours, Mike.