From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Wei Wang <wei.w.wang@intel.com>, Jason Wang <jasowang@redhat.com>,
virtualization@lists.linux-foundation.org, linux-mm@kvack.org
Subject: [PATCH v4 1/2] mm/balloon_compaction: avoid duplicate page removal
Date: Thu, 18 Jul 2019 10:00:53 -0400 [thread overview]
Message-ID: <20190718140006.15052-1-mst@redhat.com> (raw)
From: Wei Wang <wei.w.wang@intel.com>
A #GP is reported in the guest when requesting balloon inflation via
virtio-balloon. The reason is that the virtio-balloon driver has
removed the page from its internal page list (via balloon_page_pop),
but balloon_page_enqueue_one also calls "list_del" to do the removal.
This is necessary when it's used from balloon_page_enqueue_list, but
not from balloon_page_enqueue.
Move list_del to balloon_page_enqueue, and update comments accordingly.
Fixes: 418a3ab1e778 (mm/balloon_compaction: List interfaces)
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
This patch is same as v3.
mm/balloon_compaction.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 83a7b614061f..d25664e1857b 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -21,7 +21,6 @@ static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
* memory corruption is possible and we should stop execution.
*/
BUG_ON(!trylock_page(page));
- list_del(&page->lru);
balloon_page_insert(b_dev_info, page);
unlock_page(page);
__count_vm_event(BALLOON_INFLATE);
@@ -47,6 +46,7 @@ size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
list_for_each_entry_safe(page, tmp, pages, lru) {
+ list_del(&page->lru);
balloon_page_enqueue_one(b_dev_info, page);
n_pages++;
}
@@ -128,13 +128,19 @@ struct page *balloon_page_alloc(void)
EXPORT_SYMBOL_GPL(balloon_page_alloc);
/*
- * balloon_page_enqueue - allocates a new page and inserts it into the balloon
- * page list.
+ * balloon_page_enqueue - inserts a new page into the balloon page list.
+ *
* @b_dev_info: balloon device descriptor where we will insert a new page to
* @page: new page to enqueue - allocated using balloon_page_alloc.
*
* Driver must call it to properly enqueue a new allocated balloon page
* before definitively removing it from the guest system.
+ *
+ * Drivers must not call balloon_page_enqueue on pages that have been
+ * pushed to a list with balloon_page_push before removing them with
+ * balloon_page_pop. To all pages on a list, use balloon_page_list_enqueue
+ * instead.
+ *
* This function returns the page address for the recently enqueued page or
* NULL in the case we fail to allocate a new page this turn.
*/
--
MST
next reply other threads:[~2019-07-18 14:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-18 14:00 Michael S. Tsirkin [this message]
2019-07-18 14:01 ` [PATCH v4 2/2] balloon: fix up comments Michael S. Tsirkin
2019-07-18 16:48 ` Ralph Campbell
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