From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B70D13C13EC; Fri, 17 Jul 2026 09:30:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784280650; cv=none; b=Uhgw9kHElsZ+C6+t//cyMKFOSkehfkbLJe2SjqIRrycLZ1mBIY+z6UU41UBuH5+Ix13PaoRCB8cvikEJ0i6WrI4GhGwxRfCTh2H4LYB6Ntv1msjdPORwyHZ/sFbOztIjNbEoEN0raR2hIj3yqJQhC4NeAf1jCUb/IwsElCtt9OI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784280650; c=relaxed/simple; bh=H0m7Dhsc6cwDcDYsUUUUbqxe1OtV0o41W4yfsJtaFbs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QTCEbKIzofZ87EDGTCN+4I/I1/DVOQSRkS0veimvumvKDTfkgOkwl36jUZtpBvT21roxR/VeXvoilm+aRIsSz4KS60VZVOT/3LmKNhhnH5jIfHrmiUnztwYzW7y0HfXv1OBTB3vsWdcUiO9yGPJe4EJdCovrLM3yOBeSDQONf34= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hage0qV8; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hage0qV8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F2271F00A3A; Fri, 17 Jul 2026 09:30:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784280649; bh=+h4zaoETmq00jhyGu87oodp647btHp8I04KMGFhKvoo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Hage0qV8ov+h4bSwo/DoSdw1TKcPMsFVyHqX5SpTN5Lm21Gkps841nn/zy7EhlTqi 0Xr9CGqPdxEUBi2+R0hCiDbVmdzua4kW7m5QwxQECmSCsB1Y3GM5jSNXBpjsK3bjO8 SdEitfxn/E+EOpShC2Y2c8vGlf6/P899q5r3MC0dYpNQ9c9pOv8LSohf4pXiEUL667 O2pS/yztfhp+Rt/OzRSCeyOwLwhM8xI6t/OVcMKI8u0bZcoo3fuTDGGUU6xRm/vsIl rn9zc+LXhKeA7YIJeOHfYWo+CFjb/0Ru/c4jx0LAKl9Esy9+lf8VlcXt563pIv9EZl 7hYxG1sVagwXw== Message-ID: <29457fe7-0fe6-4bc0-81a8-9e67f85b3a3a@kernel.org> Date: Fri, 17 Jul 2026 11:30:44 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] virtio_balloon: avoid shrinker execution during PM suspend To: Link Lin , Andrew Morton , Vlastimil Babka , "Michael S . Tsirkin" Cc: virtualization@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, prasin@google.com, rientjes@google.com, duenwen@google.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, Ammar Faizi , jiaqiyan@google.com, ahwilkins@google.com, Greg Thelen , Alexander Duyck , jthoughton@google.com, stable@vger.kernel.org References: <20260717002311.681748-1-linkl@google.com> <20260717002311.681748-3-linkl@google.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260717002311.681748-3-linkl@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/17/26 02:22, Link Lin wrote: > During PM freeze (e.g. S4 hibernation), virtballoon_freeze() calls > remove_common() which resets the virtio device and deletes all virtqueues. > However, the balloon shrinker remains registered with core MM. > > If memory pressure occurs during S4 hibernation image creation/saving, MM > invokes virtio_balloon_shrinker_scan(), which attempts to reclaim free > pages. Although return_free_pages_to_mm() only frees pages back to MM, > reclaiming free pages under memory pressure can trigger page reporting > which might access the deleted reporting virtqueue if it is not yet > frozen, or interact with other parts of the driver in a teardown state. Yes, this does seem possible. > + > static void virtio_balloon_queue_free_page_work(struct virtio_balloon *vb) > { > if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) > @@ -871,6 +887,9 @@ static unsigned long virtio_balloon_shrinker_scan(struct shrinker *shrinker, > { > struct virtio_balloon *vb = shrinker->private_data; > > + if (READ_ONCE(vb->suspended)) > + return 0; > + > return shrink_free_pages(vb, sc->nr_to_scan); > } > > @@ -879,6 +898,9 @@ static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker, > { > struct virtio_balloon *vb = shrinker->private_data; > > + if (READ_ONCE(vb->suspended)) > + return 0; > + > return vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES; > } > > @@ -1089,8 +1111,11 @@ static void remove_common(struct virtio_balloon *vb) > update_balloon_size(vb); > > /* There might be free pages that are being reported: release them. */ > - if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) > - return_free_pages_to_mm(vb, ULONG_MAX); > + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > + spin_lock_irq(&vb->free_page_list_lock); > + __return_free_pages_to_mm(vb, ULONG_MAX); > + spin_unlock_irq(&vb->free_page_list_lock); > + } Why not set the boolean immediately after this, and call it "shrinker_disabled" instead of "suspended"? Then you can keep calling "return_free_pages_to_mm(vb, ULONG_MAX);" here. -- Cheers, David