From: Andrew Morton <akpm@linux-foundation.org>
To: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
Cc: hannes@cmpxchg.org, david@kernel.org, mhocko@kernel.org,
qi.zheng@linux.dev, shakeel.butt@linux.dev, ljs@kernel.org,
kasong@tencent.com, baohua@kernel.org, axelrasmussen@google.com,
yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev,
baolin.wang@linux.alibaba.com, yuzhao@google.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
apais@microsoft.com, rlmenge@gmail.com, stable@vger.kernel.org,
Hardik Garg <hargar@linux.microsoft.com>
Subject: Re: [PATCH v2 1/2] mm: multi-gen LRU: fix NULL lruvec->pgdat deref with memcg disabled on cmdline
Date: Sat, 17 Oct 2026 13:18:30 -0700 [thread overview]
Message-ID: <20261017131830.d698d0a474745243d5d5b7f7@linux-foundation.org> (raw)
In-Reply-To: <20261017050928.128582-1-sidchintamaneni@gmail.com>
On Sat, 17 Oct 2026 05:09:27 +0000 Siddharth Chintamaneni <sidchintamaneni@gmail.com> wrote:
> When CONFIG_MEMCG=y, lruvec_pgdat() returns lruvec->pgdat, which for the
> per-node pgdat->__lruvec is left NULL by lruvec_init() and only filled in
> lazily by mem_cgroup_lruvec(). Normally that happens early, e.g. on the
> first folio_add_lru().
>
> With cgroup_disable=memory, lru_gen_shrink_node() passes &pgdat->__lruvec
> directly to shrink_one(). If direct reclaim runs before anything has
> called mem_cgroup_lruvec() for the node, which can happen during early
> boot under memory pressure (e.g. a kdump kernel), get_swappiness() ends
> up dereferencing a NULL pgdat:
Thanks, v2 lgtm.
Maintainers: please review and let us know whether you agree with the
cc:stable on both.
prev parent reply other threads:[~2026-10-17 20:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-17 5:09 Siddharth Chintamaneni
2026-10-17 5:09 ` [PATCH v2 2/2] mm: multi-gen LRU: fix NULL lruvec->pgdat deref in get_lruvec() Siddharth Chintamaneni
2026-10-17 20:18 ` Andrew Morton [this message]
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