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Date: Tue, 7 Jul 2026 21:54:02 -0700
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From: Shakeel Butt <shakeel.butt@linux.dev>
To: Richard Chang <richardycc@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, 
	Kairui Song <kasong@tencent.com>, Qi Zheng <qi.zheng@linux.dev>, Barry Song <baohua@kernel.org>, 
	Axel Rasmussen <axelrasmussen@google.com>, Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>, 
	Johannes Weiner <hannes@cmpxchg.org>, David Hildenbrand <david@kernel.org>, 
	Michal Hocko <mhocko@kernel.org>, Lorenzo Stoakes <ljs@kernel.org>, 
	Suren Baghdasaryan <surenb@google.com>, "T . J . Mercier" <tjmercier@google.com>, 
	Martin Liu <liumartin@google.com>, Minchan Kim <minchan@kernel.org>, linux-mm@kvack.org, 
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: vmscan: abort proactive reclaim early when freezing
Message-ID: <ak3Xtrtm5iVayEx7@linux.dev>
References: <20260706081218.3438762-1-richardycc@google.com>
 <ak1XzPxbwBF72d1m@linux.dev>
 <CALC_0q9=KNnkQBE_7gC60jZ2Akj9jgL+VaDMFd7yGvqyfTJbYw@mail.gmail.com>
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On Wed, Jul 08, 2026 at 12:14:50PM +0800, Richard Chang wrote:
> On Wed, Jul 8, 2026 at 3:48 AM Shakeel Butt <shakeel.butt@linux.dev> wrote:
> >
> > Can you please explain how freezing operation was delayed due to proactive
> > reclaim?
> >
> Hi Shakeel,
> 
> When system suspend is initiated, the Power Management (PM) freezer
> attempts to freeze all user-space processes by calling
> freeze_processes(), signaling user space processes to enter the
> refrigerator. When a user-space task writes to memory.reclaim to
> trigger proactive reclaim, it executes in kernel context and enters
> the reclaim loop. Currently the task does not check  signal_pending()
> within the inner loops, it cannot abort the reclaim pass early. It
> continues reclaiming memory, ignoring the freeze request. The PM
> freezer waits for all tasks to freeze. If the proactive reclaim task
> remains in the inner loops longer than the freeze timeout, the freezer
> times out, and suspend fails.

What's so special about proactive reclaim? Why the same situation can not happen
for global or memcg reclaim?