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Mon, 20 Apr 2026 11:36:54 +0000 (GMT) Received: from [9.123.6.34] (unknown [9.123.6.34]) by smtpav05.wdc07v.mail.ibm.com (Postfix) with ESMTP; Mon, 20 Apr 2026 11:36:54 +0000 (GMT) Message-ID: <4cdb0539-550b-45c1-8c6d-c21451828458@linux.ibm.com> Date: Mon, 20 Apr 2026 17:06:52 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/sparse: remove unnecessary NULL check before allocating mem_section To: Sang-Heon Jeon , akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com Cc: linux-mm@kvack.org References: <20260419144225.2875654-1-ekffu200098@gmail.com> Content-Language: en-US From: Donet Tom In-Reply-To: <20260419144225.2875654-1-ekffu200098@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDIwMDExMCBTYWx0ZWRfX+5wseoZ1F8bn QNLj66QD/TjxCOYD3uyXAmfsd8aMxN3/jb4ubRESOqabeLw2nW8/18MjnwJAhKyXW8YO1bGJf7Q KhCyklt817Ewk9on2kBEdCva9zPshv51N3iUwK/APx4kUg43sOL1pL8868jy0oX4kq9aeKINE+x OePiEsHTmtYU2GUjGFqVHTVrP1CKeBZ7+IKws/N7b+oYf4r4ygCBs1hGORPCn4UTqFtpEPns/D3 4QDAKaM+uCM/yZ68j4xyz6r//+cyH8Qq06go7DxFxbU+qcGi3H0TM4LAL1lFi86nTF111+tZmHc WRgTiF9qehZ4OIY1B2K36Xm+UU2Q+ManCuoFm1h9yNVyubBWwxqq+TvJVQuusEAZTJ7MQ60vKAP YacsRnSIseyB7T7LUgwR/5jTtJQq/RawZ82sbdenqZO4cjwNzgTnqsp84Mxhl923Rjtk4cv/a9S RglgYQgjBvWCgmuxGxA== X-Proofpoint-GUID: 7MrMPmNuoN0degy2T3SOvfwEukYvkTgi X-Authority-Analysis: v=2.4 cv=SOJykuvH c=1 sm=1 tr=0 ts=69e60fdb cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=NIslptLVQr8rbYoGeSoA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: qAmlAQ4nIuYuWS-DpXU3w7hSDqtWMmoV X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-20_02,2026-04-17_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1015 phishscore=0 suspectscore=0 adultscore=0 impostorscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604200110 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 41AEB100012 X-Stat-Signature: 3iqehkofhyu5c16jccqmzjn7kr5rb894 X-Rspam-User: X-HE-Tag: 1776685023-605609 X-HE-Meta: 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 PWSBZcSn GbZ91q2iwrnYDIx5Zu6b9Ll7Fgina6B/7TXrXRT3+2I/y5ChfBImq40ojpTRKdS0bOeisP66ilfd1TALvIHxIrcRGdHqut2PeeT9Z2NjzVdxfUEGNEJaGbDNbpJN2lWaJ0Bg2V7Fc4IzkTCNuaOvnmZuS4IvkoXmqxTBWbR0b5rZl+sV9/DqfN6gVHmUs2m2u3EVjVTuJ7/ZhtZvWEVv6Bz9RkgeJ8jti0q8pfprR7E05bVUFlnXY25E1H/rQFdBq8t7R2Djt6lij7sZd+iuaS8YoB0czcJAUVk/9WGdXV7q8Cw2Q1wIsRVKeTtUM7kt/25MiaT5LgN2s9m9+kf9jNxz8kTTVHzTT/8GBLUQ4WjVm6Yp0Hxzf4gBp8GDuRxKpDbeWDCMFunyjuzZzWE9mkxKdsZ0GAbfh0FY/ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi On 4/19/26 8:12 PM, 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 > --- > Hello, > > While looking into boot information, I found a minor enhancement point. > If I misunderstood anything, please feel free to let me know. > > 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)) { LGTM Reviewed by: Donet Tom -Donet > - 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)