From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 71255C4450A for ; Fri, 17 Jul 2026 00:24:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C411C6B00A4; Thu, 16 Jul 2026 20:24:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BCAEF6B00A5; Thu, 16 Jul 2026 20:24:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE10D6B00A6; Thu, 16 Jul 2026 20:24:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 410F56B00A4 for ; Thu, 16 Jul 2026 20:24:47 -0400 (EDT) Received: from smtpin16.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id B1797160281 for ; Fri, 17 Jul 2026 00:24:46 +0000 (UTC) X-FDA: 84996372972.16.2C835A7 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) by imf01.hostedemail.com (Postfix) with ESMTP id 101D040008 for ; Fri, 17 Jul 2026 00:24:44 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b=croXWoyx; spf=pass (imf01.hostedemail.com: domain of 3S3ZZagUKCPYjglijemmejc.amkjglsv-kkitYai.mpe@flex--linkl.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3S3ZZagUKCPYjglijemmejc.amkjglsv-kkitYai.mpe@flex--linkl.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784247885; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kvV/YUs48FxJuWf2yjxeyeKt50HRM0qCcCCbR1JgotU=; b=LgVbwUuKMwjWxju33zWFs+R3MKpsD6+Z/YIVjnV2Pkahlo5VrThCQ6apBUNUkB87KDQCOQ tPdMYtx8x4ExLUDjKSF1HvSbA/KW5io3OB+Udz2Q/cE5HwGnIfOSk1ulpDvRX4v96Ej2Ho A7T1gnlVBWxh/TBX4Xybja50AzT4O2g= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b=croXWoyx; spf=pass (imf01.hostedemail.com: domain of 3S3ZZagUKCPYjglijemmejc.amkjglsv-kkitYai.mpe@flex--linkl.bounces.google.com designates 209.85.214.202 as permitted sender) smtp.mailfrom=3S3ZZagUKCPYjglijemmejc.amkjglsv-kkitYai.mpe@flex--linkl.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784247885; b=Sb5VLrHWWpl1GD1kLO1vaenndNslun7HLRHvyTeW2lOfJ1qu3L9LV49ldAGZ2KJ/20kjDF eslGGtpjIA2kSVZhBK8b9zCGwqWRbnM4k5+5ZgZ6yNSbqkfzBcj4xYrJgWVM++WJKdppfi pELjdKvbf8NzKXMn2hJSRthxLWrlGTk= Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2c7f385887bso170991995ad.0 for ; Thu, 16 Jul 2026 17:24:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1784247884; x=1784852684; darn=kvack.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=kvV/YUs48FxJuWf2yjxeyeKt50HRM0qCcCCbR1JgotU=; b=croXWoyxnF+L93eWpleDnnyFEX1aqHaAOpyA1aaRIdiy2tAlG4FED+kSBf5jL7jYh5 Uq3qlMIz39BhKFl5m1tfMjXBYjvDbBlk+CadLO0fOYK9vODZ1TFqGYkHfGS6vWprvrVN sjQqmahUHYaV/r1no4PRNrlc9kb6m71uG9lFlamaynK2vfPyyS7raWmn/TUmdANGvXdH DD6oixk+ccOKuYa+gCg0e1w1CvxNJQZxGlmu9aQRI37LHO9lQ1yR2YcEkoPtxmuU7sHN gqk2SGESRcQAFNUfCQjNbx6go38URHXO89g4pd9dvWb0fGXIuM1Zlvg2x14at8tWRKsB VP8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784247884; x=1784852684; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=kvV/YUs48FxJuWf2yjxeyeKt50HRM0qCcCCbR1JgotU=; b=P/xGFu/eISWKJMOkfcugRP4gx57IzI6dhJW8ppC5RWr3dlu/tmhLAO/Mj2188kVTmG u06hsZ/mM53rncrseCHsukHqEXncFchuJCqs903FG0NZpSfcQdj/OW/rH1sRJfqfdeSS v63BQ5d4wO8eci0OFCq5fOjzYx4PKQnsMRIdzz2hcLw/6VvY8o3R05Eg/XNGYetTm4RD T4CaL064UZ11cU709olY/y7WqBf60xhN+3Cj19J4uWoj+mGK6DA4lTVjZFMWGWtya39P bOHXRV92geVU0Ezg7+ItyjNs6lPKtsiK7yt5ttuQOnYcWR7NVauJn/X3AVsSFYJl2XOg k7Fg== X-Forwarded-Encrypted: i=1; AHgh+Rp2uy3+eaKVYHCm6nfoAn4wr2YpndLEDDPEMMuEWq2MNhHag9EtoLCNvSuvgAfgvzcWKHTDHiWKNw==@kvack.org X-Gm-Message-State: AOJu0YzkDoy9EKGhqFQ/VvFSCxtD32KIAbMDKk2Ka5fb73t0e6aTGZyF I5N8Pz8ZLb0YMpywcggqTr9DDFn0HWqAYv5OVY7bJrU5K2Mrq1sSXj5xmkobIt4gA/D7n374+kQ bnQ== X-Received: from pjbds23.prod.google.com ([2002:a17:90b:8d7:b0:389:a1f7:c74d]) (user=linkl job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1345:b0:37f:9ce1:cdb0 with SMTP id 98e67ed59e1d1-38e4b55aeccmr247935a91.30.1784247883538; Thu, 16 Jul 2026 17:24:43 -0700 (PDT) Date: Fri, 17 Jul 2026 00:22:21 +0000 In-Reply-To: <20260717002311.681748-1-linkl@google.com> Mime-Version: 1.0 References: <20260717002311.681748-1-linkl@google.com> X-Mailer: git-send-email 2.55.0.229.g6434b31f56-goog Message-ID: <20260717002311.681748-3-linkl@google.com> Subject: [PATCH v2 2/2] virtio_balloon: avoid shrinker execution during PM suspend From: Link Lin To: Andrew Morton , Vlastimil Babka , "Michael S . Tsirkin" , David Hildenbrand 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, Link Lin Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 101D040008 X-Stat-Signature: 9smrjg7ranb5zijswgbjew5g8eim7nyu X-HE-Tag: 1784247884-470651 X-HE-Meta: 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 bpRj+9IA 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Avoid this by adding a `suspended` flag to `struct virtio_balloon`. Set this flag to true in virtballoon_freeze() and false in virtballoon_restore(). Check this flag in both shrinker callbacks (scan and count) and return 0 if the device is suspended, preventing any shrinker execution while virtqueues are deleted. Wrap the lockless reads in READ_ONCE() and writes in WRITE_ONCE() to prevent compiler optimization issues and KCSAN data race warnings. Fixes: 71019de8219b ("virtio_balloon: Add free page hinting support") Cc: stable@vger.kernel.org Acked-by: David Rientjes Signed-off-by: Link Lin --- drivers/virtio/virtio_balloon.c | 49 +++++++++++++++++++++++++++------ 1 file changed, 41 insertions(+), 8 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 088b3a0e6c..38e1166a64 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -68,6 +68,8 @@ struct virtio_balloon { /* Prevent updating balloon when it is being canceled. */ spinlock_t stop_update_lock; bool stop_update; + /* Prevent shrinker from running while device is suspended. */ + bool suspended; /* Bitmap to indicate if reading the related config fields are needed */ unsigned long config_read_bitmap; @@ -471,9 +473,9 @@ static inline s64 towards_target(struct virtio_balloon *vb) return target - vb->num_pages; } -/* Gives back @num_to_return blocks of free pages to mm. */ -static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, - unsigned long num_to_return) +/* Helper: must be called with free_page_list_lock held */ +static unsigned long __return_free_pages_to_mm(struct virtio_balloon *vb, + unsigned long num_to_return) { unsigned long num_returned = 0; struct page *page, *next; @@ -481,8 +483,6 @@ static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, if (unlikely(!num_to_return)) return 0; - spin_lock_irq(&vb->free_page_list_lock); - list_for_each_entry_safe(page, next, &vb->free_page_list, lru) { list_del(&page->lru); __free_pages(page, VIRTIO_BALLOON_HINT_BLOCK_ORDER); @@ -490,11 +490,27 @@ static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, break; } vb->num_free_page_blocks -= num_returned; - spin_unlock_irq(&vb->free_page_list_lock); return num_returned; } +/* Gives back @num_to_return blocks of free pages to mm. */ +static unsigned long return_free_pages_to_mm(struct virtio_balloon *vb, + unsigned long num_to_return) +{ + unsigned long ret; + + spin_lock_irq(&vb->free_page_list_lock); + if (vb->suspended) { + spin_unlock_irq(&vb->free_page_list_lock); + return 0; + } + ret = __return_free_pages_to_mm(vb, num_to_return); + spin_unlock_irq(&vb->free_page_list_lock); + + return ret; +} + 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); + } /* Now we reset the device so we can clean up the queues. */ virtio_reset_device(vb->vdev); @@ -1133,6 +1158,10 @@ static int virtballoon_freeze(struct virtio_device *vdev) * The workqueue is already frozen by the PM core before this * function is called. */ + spin_lock_irq(&vb->free_page_list_lock); + WRITE_ONCE(vb->suspended, true); + spin_unlock_irq(&vb->free_page_list_lock); + remove_common(vb); return 0; } @@ -1148,6 +1177,10 @@ static int virtballoon_restore(struct virtio_device *vdev) virtio_device_ready(vdev); + spin_lock_irq(&vb->free_page_list_lock); + WRITE_ONCE(vb->suspended, false); + spin_unlock_irq(&vb->free_page_list_lock); + if (towards_target(vb)) virtballoon_changed(vdev); update_balloon_size(vb); -- 2.55.0.229.g6434b31f56-goog