Fwd: [BUG] rcu_tasks detected stalls in kcompactd during proactive compaction

[ying chen]

---------- Forwarded message ---------
From: ying chen <yc1082463@xxxxxxxxx>
Date: Tue, Mar 24, 2026 at 4:26 PM
Subject: [BUG] rcu_tasks detected stalls in kcompactd during proactive
compaction
To: <linux-mm@xxxxxxxxx>, <linux-kernel@xxxxxxxx>,
<paulmck@xxxxxxxxxx>, <akpm@xxxxxxxxxxxxxxxxxxxx>


Hi all,
I encountered an RCU tasks stall issue triggered by kcompactd0 on my
system.Below are the details of the incident:

Kernel Version：6.1.0-x
vm.compaction_proactiveness = 20
CONFIG_PREEMPT_RCU=y

[Sun Mar 22 16:36:04 2026] INFO: rcu_tasks detected stalls on tasks:
[Sun Mar 22 16:36:04 2026] 00000000fcafb4d6: .. nvcsw: 622963/622963
holdout: 1 idle_cpu: -1/1
[Sun Mar 22 16:36:04 2026] task:kcompactd0      state:R running task
 stack:0         pid:1943
[Sun Mar 22 16:36:04 2026] Call Trace:
[Sun Mar 22 16:36:04 2026]  <TASK>
[Sun Mar 22 16:36:04 2026]  ? rmap_walk_anon+0x16b/0x330
[Sun Mar 22 16:36:04 2026]  ? try_to_migrate+0x96/0x110
[Sun Mar 22 16:36:04 2026]  ? try_to_unmap_one+0xd0/0xd0
[Sun Mar 22 16:36:04 2026]  ? anon_vma_ctor+0x50/0x50
[Sun Mar 22 16:36:04 2026]  ? folio_get_anon_vma+0x90/0x90
[Sun Mar 22 16:36:04 2026]  ? invalid_mkclean_vma+0x20/0x20
[Sun Mar 22 16:36:04 2026]  ? __unmap_and_move+0x21e/0x340
[Sun Mar 22 16:36:04 2026]  ? free_unref_page+0x17d/0x1f0
[Sun Mar 22 16:36:04 2026]  ? release_freepages+0xc0/0xc0
[Sun Mar 22 16:36:04 2026]  ? release_freepages+0xc0/0xc0
[Sun Mar 22 16:36:04 2026]  ? unmap_and_move+0xaa/0x4c0
[Sun Mar 22 16:36:04 2026]  ? migrate_pages+0x3a9/0x790
[Sun Mar 22 16:36:04 2026]  ? release_freepages+0xc0/0xc0
[Sun Mar 22 16:36:04 2026]  ? isolate_migratepages+0x2a0/0x2a0
[Sun Mar 22 16:36:04 2026]  ? compact_zone+0x310/0x5d0
[Sun Mar 22 16:36:04 2026]  ? proactive_compact_node+0x88/0xc0
[Sun Mar 22 16:36:04 2026]  ? kcompactd+0x365/0x3f0
[Sun Mar 22 16:36:04 2026]  ? membarrier_register_private_expedited+0xa0/0xa0
[Sun Mar 22 16:36:04 2026]  ? kcompactd_do_work+0x2a0/0x2a0
[Sun Mar 22 16:36:04 2026]  ? kthread+0xeb/0x120