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a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785931429; b=Xy6BSZ+12ubO8mgL7MDfBCyHT+LAEEaiRUuIA7HYfdBcw9ExZNQhK+GOsngZsXaWhD3Wek zcoiPP9Bo+ADyAloI20rf/vfDczcjXef9GGbN9riM7smk6UOla/Mi6pas+qmEV1ItRGOzV zjUCEaiGjsC0SDwIj0+bWqh+geyZlG4= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b="NDYF/i3G"; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id BA82860A9D; Wed, 5 Aug 2026 12:03:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB64C1F00ACA; Wed, 5 Aug 2026 12:03:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785931428; bh=/TxnOeGfIBpnExbybgGUK7PctnBzRbPKKrr+zPKrO7c=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=NDYF/i3GHNA+/IHT24tL5hwQavM5fu/ZoSDW+J9bbFkcuRP8SsjnM15hTBdETAfkV Wakg7UP63JLO7jYu2GYy/+4FSFdzK2IX6KKeddR7B26sh1Db8DtfOj2SQ5wVgBi2xx uW2Wail8EKoiFOuj38AdJp+kl07jMXgbGa2gbY0HVGuxg/0BPNAouvXX7dqzRdnOnx jvR41xDH0Vp4VOFDL3/uzlyafGPdiBMP7uhbK8fTFRY+zsXgkILJeXMIZuVAkDDIxP vn6U11lvFwg0nP2qEx2bNvUcI/86FTiemcTKX/YLgMiuWe2OpWdeUnd3/s3WIBfnQm 2WmAhmyrhRrOQ== Message-ID: <0b48002f-8e2c-41b3-b8ef-69f200b02330@kernel.org> Date: Wed, 5 Aug 2026 14:03:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm/page_reporting: Add page_reporting_delay_ms module parameter To: Andrew Morton , pratmal@google.com Cc: vbabka@kernel.org, sj@kernel.org, corbet@lwn.net, ljs@kernel.org, skhan@linuxfoundation.org, anshuman.khandual@arm.com, gthelen@google.com, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, liam@infradead.org, rppt@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org References: <20260731193705.2902728-1-pratmal@google.com> <20260731143420.0787387ce2ca120ecee15338@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspam-User: X-Stat-Signature: rw83q1zrcopx4etieyb6aqdnoku5ez3o X-Rspamd-Queue-Id: 350441C0011 X-HE-Tag: 1785931429-224846 X-HE-Meta: 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 k/kAXTUX u4tdIoXHkeYMSjSslEQQzWSef5rNsZ2Wc5mCJLIaS7mUU1jeFtIdKgp9a0vRQuFAQcSaWRDpKw9vQJZdUJpz7EteL/6UmPHawwy/2Le3/pzx73A5r201HHTfQXjHh6jj6g9UIcGSUim9TmK7jfYoVeIh72hIxNrvDd10BJ3/vClDXyHZ3+/v4/BD/on9vVxXU+RDke43t5CU2SxPN1XV4QYnV9LidZ8TjDTVMyl89gAC2xhaq1IPPI0qzmUsaVjjiWADRHrxZfcYqu9kNEF/JENo1MHD9y9WB70jlHdssamzid7BJC+aeXmSbjAlomeF9ZAonoEtU1huWHLOYlZwLp7OzZGM3BtiPx4Il Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/31/26 23:34, Andrew Morton wrote: > On Fri, 31 Jul 2026 19:37:05 +0000 pratmal@google.com wrote: > >> Free page reporting currently hardcodes a 2-second interval between >> reports. This rigid delay cannot accommodate diverse guest workloads. >> >> This patch introduces a module parameter, page_reporting_delay_ms >> (default: 2000), allowing users to tune the reporting rate: >> - Lower values enable aggressive memory reclamation by returning unused >> pages to the host immediately. >> - Higher values help batch pages during spiky allocation/free churn, >> reducing hypercalls and nested page fault overheads. >> >> Setting the delay to 0 is safe and execution is strictly gated by: >> - reporting is only triggered by high-order page frees. >> - expensive hypercalls are bounded by a slot capacity watermark check >> before proceeding. > > This conflcits with the just-upstreamed 0b45f6927a1 > ("mm/page_reporting: use system_freezable_wq to fix UAF during > suspend") > (https://lore.kernel.org/20260721005603.1710551-1-linkl@google.com). > > Please review my resolution: > > --- a/mm/page_reporting.c~mm-page_reporting-add-page_reporting_delay_ms-module-parameter > +++ a/mm/page_reporting.c > @@ -48,7 +48,11 @@ MODULE_PARM_DESC(page_reporting_order, " > */ > EXPORT_SYMBOL_GPL(page_reporting_order); > > -#define PAGE_REPORTING_DELAY (2 * HZ) > +static unsigned int page_reporting_delay_ms = 2 * MSEC_PER_SEC; > +module_param(page_reporting_delay_ms, uint, 0644); > +MODULE_PARM_DESC(page_reporting_delay_ms, > + "Set page reporting delay in milliseconds"); > + > static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly; > > enum { > @@ -57,6 +61,13 @@ enum { > PAGE_REPORTING_ACTIVE > }; > > +/* schedule work for page reporting */ > +static void page_reporting_schedule_work(struct page_reporting_dev_info *prdev) > +{ > + queue_delayed_work(system_freezable_wq, &prdev->work, > + msecs_to_jiffies(page_reporting_delay_ms)); ^ just double checking whether that is indented properly . Acked-by: David Hildenbrand (Arm) -- Cheers, David