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AHgh+RoIx7OCXcZtJJQCBkPksc+oaRxrXFMXnjcDIrzBKb2PYqu3x372XuiQHAiVdNPAQxiKa2XoGzbBzhvYTFU=@vger.kernel.org X-Gm-Message-State: AOJu0YwbccqZ0Gct5/bR4PHUfMENXFzEXNsUJDsoXTQ6lBoljjlZN5L7 bWAI2ZS8N3wUdI+lmXFp5DUZGO9bTFM7RbB58rIXX+FVclDSl2ckMO0fZJeAP4tT3Aeamr+WMmv 1dQ5/TF7QW70wztbMaqOtyLhVeVLsUXolWXZ7He8= X-Gm-Gg: AfdE7clo2go6/PkzQR3hq8y9sHzzXZ/fp+NV2itnA4FillsAldKAsRoj5C189I5rFAw tZ96WLhkxfc4637dM7K4jshhke4oNpjqtiOD9Gki9rkK+qTAP3zp2BQhBRuJd6dWR4E1F2x/Tp3 1u31eRcFr1KhAT6UhcyfOOOnclO9CiO9sTchBUd3nYU3Dw+4gqyzP52ulqWz0JLvWZN6xZF1xjx gMZxUBYkLmEREZCnwPG8yNyQOVL/AHri6v2HqCTljPu/v04P8iiRPue+r9cQcEFC1irSfsl X-Received: by 2002:a05:6512:23a5:b0:5a4:ec:53d9 with SMTP id 2adb3069b0e04-5b155404c3emr241368e87.1.1784019649761; Tue, 14 Jul 2026 02:00:49 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20260709072231.3163082-1-richardycc@google.com> In-Reply-To: From: Richard Chang Date: Tue, 14 Jul 2026 17:00:37 +0800 X-Gm-Features: AUfX_mwwn9GNSOxlfwNhHRs2loR1dqTk-SQ3OqTOyRyw6UbPKyV0ArIMxDzSqXM Message-ID: Subject: Re: [PATCH v2] mm: vmscan: abort proactive reclaim early when freezing for suspend To: Michal Hocko Cc: Andrew Morton , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Johannes Weiner , David Hildenbrand , Lorenzo Stoakes , Suren Baghdasaryan , "T . J . Mercier" , Martin Liu , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Michal, On Fri, Jul 10, 2026 at 2:27=E2=80=AFPM Michal Hocko wrot= e: > > I believe this is a wrong behavior. Freezer should be invisible from the > userspace POV. Your patch makes the pre-existing problem much more > visible. I believe we need a slightly different approach. Should we > try_to_freeze in well defined places in the reclaim and turn > user_proactive_reclaim to fatal_signal_pending? > I believe your perspective is that we should avoid -EINTR during suspend by transparently pausing and resuming the task rather than aborting the system call. However, this approach faces a few constraints: 1. fatal_signal_pending() only addresses SIGKILL, leaving us to still handle standard non-fatal signals, such as SIGINT/Ctrl+C, for userspace callers. 2. Calling try_to_freeze() deep within the reclaim path is complex, as it may hold various locks (such as RCU, page, or cgroup locks) while suspended. 3. Since -EINTR is already the established return behavior in user_proactive_reclaim() when interrupted by signal_pending(), robust userspace callers should already be equipped to handle this early return. On the other hand, the freezer timeout/suspend failure is a genuine bug currently impacting Android devices in the field. The proposed patch safely addresses this immediate issue by leveraging the pre-existing -EINTR exit path in user_proactive_reclaim(). Could we focus on the current patch and open a separate discussion for a more ideal, long-term design regarding freezer invisibility as a follow-up?