From: Shakeel Butt <shakeel.butt@linux.dev>
To: Farhad Alemi <farhad.alemi@berkeley.edu>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
falemi@asu.edu, cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [BUG] refill_stock -- VM_WARN_ON_ONCE(mem_cgroup_is_root()) from a write to the cgroup-v2 root's memory.reclaim
Date: Fri, 28 Aug 2026 09:53:50 -0700 [thread overview]
Message-ID: <apG8lKU0xDitsvV7@linux.dev> (raw)
In-Reply-To: <CA+0ovCgWzUMK+nNbbtH7eV65Ca=fDN4Ozu7iASgryjvv8Tk8zQ@mail.gmail.com>
On Thu, Aug 27, 2026 at 10:28:57PM -0700, Farhad Alemi wrote:
> Hello,
>
> As part of the kernel research at ASU's SEFCOM
> lab, we hit the crash below. Crash reports can be found here:
>
> https://github.com/farhad-alemi/public_bug_reports/tree/main/145-memcg-vm_warn-refill_stock-root-cgroup/
>
> mem_cgroup_is_root(memcg)
> WARNING: mm/memcontrol.c:2198 at refill_stock+0x644/0x940, CPU#1: repro/9490
> Call Trace:
> refill_stock+0x644/0x940
> try_charge_memcg+0x12d6/0x1570
> __obj_cgroup_charge+0x35/0xf0
> obj_cgroup_charge+0x1de/0x210
> obj_cgroup_charge_zswap+0x83/0x270
> zswap_store+0x1620/0x2000
> swap_writeout+0x94c/0x14c0
> shrink_folio_list+0x3388/0x52b0
> evict_folios+0x374d/0x48c0
> try_to_shrink_lruvec+0xe72/0x1350
> shrink_node+0x3320/0x3b90
> do_try_to_free_pages+0x6a2/0x1990
> try_to_free_mem_cgroup_pages+0x30d/0x830
> user_proactive_reclaim+0x504/0x840
> memory_reclaim+0x1f/0x30
> cgroup_file_write+0x331/0x8f0
> kernfs_fop_write_iter+0x3af/0x540
>
> Our reproducer.c is available upon request.
>
> Happy to test a patch if that would help.
Thanks for the report. Please test the following patch. I will send formal patch
after your testing.
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4a18ee4509ab..1709ac96bbde 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3157,7 +3157,7 @@ static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
memcg = get_mem_cgroup_from_objcg(objcg);
- ret = try_charge_memcg(memcg, gfp, nr_pages);
+ ret = try_charge(memcg, gfp, nr_pages);
if (ret)
goto out;
prev parent reply other threads:[~2026-08-28 16:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 5:28 [BUG] refill_stock -- VM_WARN_ON_ONCE(mem_cgroup_is_root()) from a write to the cgroup-v2 root's memory.reclaim Farhad Alemi
2026-08-28 16:53 ` Shakeel Butt [this message]
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