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Thu, 26 Mar 2026 07:01:40 +0000 (GMT) From: Donet Tom To: David Hildenbrand , Andrew Morton , Ingo Molnar , Peter Zijlstra Cc: Ritesh Harjani , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Baolin Wang , Ying Huang , Juri Lelli , Mel Gorman , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Donet Tom Subject: [PATCH] sched/numa, mm: Skip page promotion if cpu pid is valid Date: Thu, 26 Mar 2026 02:12:16 -0500 Message-ID: <20260326071216.11883-1-donettom@linux.ibm.com> X-Mailer: git-send-email 2.47.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: CiaSF-H1fnPPyV5xXc-MOYz_Qk5Hvnp8 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzI2MDA0OSBTYWx0ZWRfX4KLfaAC6v9T5 PRpSrbBqH09ZlYLbFNG3BZ6ZBuoLbcHwrQrVnCIrVtpPdFjb0blSvwXRjcT6NtxbHSqGvZsQA5Y zhNPEUdV2i1fkRfSyr7QMiNMlenU3qjN92lBESP9Q6GfMuMA4Jt+iMvrcvK2mNR6pP3TfbLetbG U4pVtmFM+zAoLf/zLIxVmBXj0L+PLa17xYnSGWZvJzzvXMKuAagOIGeX/AVRyqHDQMyEAYWm8Bz M6C41n6axuXvqCGuOR5Ux9kitHlWmFBqQzhUMH1eLAjnMZpfhbaWqkV1Yz0XO38uDunhDjdCjnu Dt7d16reyiOaFFNoGMUewV1F50jYOtm6HJ/2zRgY6wdpV5zzMdQxlqTEnWr8he4keo8a7QXxsak r9hJTEWew0hOVVOdwrXweTNmRBGfF6QN1eeyUWnbVPdSZFShm+xQmeciL8KXbYB12/l4tNbYemC EF8L2fPYf9j26oWAx7A== X-Authority-Analysis: v=2.4 cv=bLEb4f+Z c=1 sm=1 tr=0 ts=69c4d9db cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=BU45FUZf6EOTpP1Kgp0A:9 X-Proofpoint-GUID: MJCi38OmNnXbfplKA4HoCHDbAQwVLJJo 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=2026-03-26_02,2026-03-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 clxscore=1011 phishscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603260049 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D3E0B80003 X-Stat-Signature: fe5na7dj49n7rpahfn77cx3qej45fzkn X-Rspam-User: X-HE-Tag: 1774508541-695481 X-HE-Meta: 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 e2lqV7O/ OI3iKpsNmuRZ7IRJ88KuUs4mZ+jH434MjrBbWluAhie54PVrF+YvuTDEhK18OvjdJCFJWRn67K/++ezAoVVV31ZnbNCEgituw26HNLkFxy809hZm06LiWIsH/Xx0C79wj0uIzu2QEqL2Z95wA89G8JKQvBhzbHpdWx75HGbxMV2+mcLU+SRamPqIbNmqb055NTNxQy8Ps+zD2LIQrP2GKFDnAdSUpnyI1JMmMwHbo6pyXOM4VS/3JmjK0jxKa9Dvz/mTLx/3N/LdXCPmbwT184vSQpw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: If memory tiering is disabled, cpupid of slow memory pages may contain a valid CPU and PID. If tiering is enabled at runtime, there is a chance that in should_numa_migrate_memory(), this valid CPU/PID is treated as a last access timestamp, leading to unnecessary promotion. Prevent this by skipping promotion when cpupid is valid. Signed-off-by: Donet Tom --- kernel/sched/fair.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4b43809a3fb1..f5830a5a94d5 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2001,6 +2001,13 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio, unsigned int latency, th, def_th; long nr = folio_nr_pages(folio); + /* When tiering is enabled at runtime, last_cpupid may + * hold a valid cpupid instead of an access timestamp. + * If so, skip page promotion. + */ + if (cpupid_valid(folio_last_cpupid(folio))) + return false; + pgdat = NODE_DATA(dst_nid); if (pgdat_free_space_enough(pgdat)) { /* workload changed, reset hot threshold */ -- 2.47.1