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[109.81.22.50]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47aa039ad21sm56217525f8f.20.2026.07.09.23.27.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2026 23:27:40 -0700 (PDT) Date: Fri, 10 Jul 2026 08:27:39 +0200 From: Michal Hocko To: Richard Chang 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 Subject: Re: [PATCH v2] mm: vmscan: abort proactive reclaim early when freezing for suspend Message-ID: References: <20260709072231.3163082-1-richardycc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8FF49160005 X-Stat-Signature: hsx6ujhx4mmnyyyztokiiw33sy16k34i X-HE-Tag: 1783664862-576903 X-HE-Meta: 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 LD2B7Rp1 tAjH1lS6psyfj4umX/5O1ffCuqXzW0aHwFz8EbiXjQQ4LOt3kl80vZozzyNJnMp1WEAk/yOcmO8J9duAQEB7/ZwWycPiqA6tFD3lAUXAeipsf+g+UqUedbhEl0CKX8U4KH68wxFDo5597eruDPP2Oooazr1/xPULxxCm4cT5NaD+nHvvuToEjEQbFrFeu1NruyMSecagYkWE0akNzRLEvq99CyVvPXD2b3IbTXxmlDZp5zV3zyh/g29zLyNZpePtyHOeWLYmBD2U/i4L8Pmc4LBNNXlxmLWV5TWXiOGH8T1RNakfXJ+f3z9tKIPlOQ71akgDp2a1t9E9yFGqlNTAxok+pLWVd6ZgoYdsPRSFxVJfo1gM+NpDbSq5cdOdBqDD0tSK4EPmbxWNVVvOCrDTjN484HsdOhbtgyOAyKc/y2/p+fS74DAFbuTRwMDtfVHIz4z03 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri 10-07-26 11:29:25, Richard Chang wrote: > Hi Michal, > > On Thu, Jul 9, 2026 at 8:06 PM Michal Hocko wrote: > > > > The changelog doesn't explain whether this is MGRLU specific problem as > > the fix is MGRLU specific AFAICS. > > > I will prepare the v3 changelog update. Thanks. > > > Also do I get it right that freezing a task while doing the pro-active > > reclaim will force EINTR early return even if no real signal was > > delivered to the task? > > > Yes, that is correct. > The PM freezer ( freeze_task() ) calls fake_signal_wake_up(), which > sets TIF_SIGPENDING on the target task. > Returning -EINTR when checking by signal_pending(current) is already > the existing behavior of user_proactive_reclaim(). > This patch does not change the behavior, it just allows the task to > exit the inner loop quickly. 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? -- Michal Hocko SUSE Labs