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Thu, 04 Jun 2026 13:42:41 +0000 (GMT) Received: from pps.filterd (phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (8.18.1.7/8.18.1.7) with ESMTP id 654DdjP0001204; Thu, 4 Jun 2026 13:42:40 GMT Received: from imran-metabox.au.oracle.com (dhcp-10-191-115-51.vpn.oracle.com [10.191.115.51]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 4efpbfwatb-1; Thu, 04 Jun 2026 13:42:40 +0000 (GMT) From: Imran Khan To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/vmstat: avoid taking zone lock in /proc/buddyinfo reads Date: Thu, 4 Jun 2026 21:42:45 +0800 Message-Id: <20260604134245.1580287-1-imran.f.khan@oracle.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-04_04,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 adultscore=0 suspectscore=0 phishscore=0 malwarescore=0 bulkscore=0 spamscore=0 mlxlogscore=999 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2605130000 definitions=main-2606040133 X-Authority-Analysis: v=2.4 cv=NLnlPU6g c=1 sm=1 tr=0 ts=6a2180d1 b=1 cx=c_pps a=WeWmnZmh0fydH62SvGsd2A==:117 a=WeWmnZmh0fydH62SvGsd2A==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=jiCTI4zE5U7BLdzWsZGv:22 a=3I1J8UUJPc9JN9BFgKH3:22 a=yPCof4ZbAAAA:8 a=YhumCNMSV65wbhEYhDcA:9 X-Proofpoint-GUID: pAa5fQDIeDXB7xp4SIyCmHOP4A8V3zu5 X-Proofpoint-ORIG-GUID: pAa5fQDIeDXB7xp4SIyCmHOP4A8V3zu5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjA0MDEzMyBTYWx0ZWRfX1XST2npXnF+U BveeUULTvCursnK7A7KCROvMx+IB7k+d8KFAj2C1it3tgi8bYH/anK9DeV7lb3f0tZAciBRTBgQ ULNYn4HtRt/M9/6qcFJJ3s4RKwciIKYUXjOMyjtF9YNpKufba3K3X42uDSaD/D9KU//tovh/voM JzPKl7h4Ie0Ru+yszy/JmzpTO5k0k4PTHO5HQlH4DifMuVGaDKvk6mhSxVuQ71a8c2EGg6bL0L2 hYLtqwPzeSBQOvqH7aRrMkQzIz0Dt2ybUOdmXKfDNJEusCao3/wKqOQAj5ZqBCO1wJtNiwNN+e/ C4UiItG3VJXX9IzimQF6CWHgqMWmoIK9PMY3OjPWyT4mf3Wac1VhgYyop8Hl24UOChLAxmt82Da 5JrRY9LXhsb/lmdS7oIucl9O5/K8xMNjU/dbW67Wf5VjzaOGr9EZCu4OqElZrkTg+joNgs3l5eP fveCgnnU2TMOZ5U6wCQ== Content-Type: text/plain; charset="utf-8" frag_show_print() just reads zone->free_area[order].nr_free, so it can safely do this without needing the zone->lock. Pass nolock=3Dtrue from frag_show(), so that walk_zones_in_node() can skip the zone->lock acquisition. Signed-off-by: Imran Khan Acked-by: Vlastimil Babka (SUSE) Reviewed-by: Joshua Hahn Reviewed-by: Lorenzo Stoakes --- mm/vmstat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/vmstat.c b/mm/vmstat.c index f534972f517de..7b93fbf9af092 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1568,7 +1568,7 @@ static void frag_show_print(struct seq_file *m, pg_da= ta_t *pgdat, static int frag_show(struct seq_file *m, void *arg) { pg_data_t *pgdat =3D (pg_data_t *)arg; - walk_zones_in_node(m, pgdat, true, false, frag_show_print); + walk_zones_in_node(m, pgdat, true, true, frag_show_print); return 0; } =20 base-commit: e43ffb69e0438cddd72aaa30898b4dc446f664f8 --=20 2.34.1