balloon: fix up comments (cfe61801) · Commits · 戴 / test

mm/balloon_compaction.c

+37 −30

Original line number	Diff line number	Diff line
		@@ -32,8 +32,8 @@ static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
		* @b_dev_info: balloon device descriptor where we will insert a new page to
		* @pages: pages to enqueue - allocated using balloon_page_alloc.
		*
		* Driver must call it to properly enqueue a balloon pages before definitively
		* removing it from the guest system.
		* Driver must call this function to properly enqueue balloon pages before
		* definitively removing them from the guest system.
		*
		* Return: number of pages that were enqueued.
		*/
		@@ -63,12 +63,13 @@ EXPORT_SYMBOL_GPL(balloon_page_list_enqueue);
		* @n_req_pages: number of requested pages.
		*
		* Driver must call this function to properly de-allocate a previous enlisted
		* balloon pages before definetively releasing it back to the guest system.
		* balloon pages before definitively releasing it back to the guest system.
		* This function tries to remove @n_req_pages from the ballooned pages and
		* return them to the caller in the @pages list.
		*
		* Note that this function may fail to dequeue some pages temporarily empty due
		* to compaction isolated pages.
		* Note that this function may fail to dequeue some pages even if the balloon
		* isn't empty - since the page list can be temporarily empty due to compaction
		* of isolated pages.
		*
		* Return: number of pages that were added to the @pages list.
		*/
		@@ -114,10 +115,11 @@ EXPORT_SYMBOL_GPL(balloon_page_list_dequeue);
		* balloon_page_alloc - allocates a new page for insertion into the balloon
		* page list.
		*
		* Driver must call it to properly allocate a new enlisted balloon page.
		* Driver must call balloon_page_enqueue before definitively removing it from
		* the guest system. This function returns the page address for the recently
		* allocated page or NULL in the case we fail to allocate a new page this turn.
		* Driver must call this function to properly allocate a new balloon page.
		* Driver must call balloon_page_enqueue before definitively removing the page
		* from the guest system.
		*
		* Return: struct page for the allocated page or NULL on allocation failure.
		*/
		struct page *balloon_page_alloc(void)
		{
		@@ -130,19 +132,15 @@ EXPORT_SYMBOL_GPL(balloon_page_alloc);
		/*
		* 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
		* @b_dev_info: balloon device descriptor where we will insert a new page
		* @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 call this function to properly enqueue a new allocated balloon
		* page before definitively removing the page 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.
		* 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
		* enqueue a list of pages, use balloon_page_list_enqueue instead.
		*/
		void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
		struct page *page)
		@@ -157,14 +155,23 @@ EXPORT_SYMBOL_GPL(balloon_page_enqueue);

		/*
		* balloon_page_dequeue - removes a page from balloon's page list and returns
		* the its address to allow the driver release the page.
		* its address to allow the driver to release the page.
		* @b_dev_info: balloon device decriptor where we will grab a page from.
		*
		* Driver must call it to properly de-allocate a previous enlisted balloon page
		* before definetively releasing it back to the guest system.
		* This function returns the page address for the recently dequeued page or
		* NULL in the case we find balloon's page list temporarily empty due to
		* compaction isolated pages.
		* Driver must call this function to properly dequeue a previously enqueued page
		* before definitively releasing it back to the guest system.
		*
		* Caller must perform its own accounting to ensure that this
		* function is called only if some pages are actually enqueued.
		*
		* Note that this function may fail to dequeue some pages even if there are
		* some enqueued pages - since the page list can be temporarily empty due to
		* the compaction of isolated pages.
		*
		* TODO: remove the caller accounting requirements, and allow caller to wait
		* until all pages can be dequeued.
		*
		* Return: struct page for the dequeued page, or NULL if no page was dequeued.
		*/
		struct page balloon_page_dequeue(struct balloon_dev_info b_dev_info)
		{
		@@ -177,9 +184,9 @@ struct page balloon_page_dequeue(struct balloon_dev_info b_dev_info)
		if (n_pages != 1) {
		/*
		* If we are unable to dequeue a balloon page because the page
		* list is empty and there is no isolated pages, then something
		* list is empty and there are no isolated pages, then something
		* went out of track and some balloon pages are lost.
		* BUG() here, otherwise the balloon driver may get stuck into
		* BUG() here, otherwise the balloon driver may get stuck in
		* an infinite loop while attempting to release all its pages.
		*/
		spin_lock_irqsave(&b_dev_info->pages_lock, flags);
		@@ -230,8 +237,8 @@ int balloon_page_migrate(struct address_space *mapping,

		/*
		* We can not easily support the no copy case here so ignore it as it
		* is unlikely to be use with ballon pages. See include/linux/hmm.h for
		* user of the MIGRATE_SYNC_NO_COPY mode.
		* is unlikely to be used with balloon pages. See include/linux/hmm.h
		* for a user of the MIGRATE_SYNC_NO_COPY mode.
		*/
		if (mode == MIGRATE_SYNC_NO_COPY)
		return -EINVAL;

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