balloon: fix up comments
Lots of comments bitrotted. Fix them up.
Fixes: 418a3ab1e7 (mm/balloon_compaction: List interfaces)
Reviewed-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Acked-by: Nadav Amit <namit@vmware.com>
alistair/sunxi64-5.4-dsi
Michael S. Tsirkin
parent
dd42290679
commit
cfe61801b0
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@ -32,8 +32,8 @@ static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
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* @b_dev_info: balloon device descriptor where we will insert a new page to
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* @pages: pages to enqueue - allocated using balloon_page_alloc.
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*
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* Driver must call it to properly enqueue a balloon pages before definitively
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* removing it from the guest system.
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* Driver must call this function to properly enqueue balloon pages before
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* definitively removing them from the guest system.
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*
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* Return: number of pages that were enqueued.
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*/
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@ -63,12 +63,13 @@ EXPORT_SYMBOL_GPL(balloon_page_list_enqueue);
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* @n_req_pages: number of requested pages.
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*
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* Driver must call this function to properly de-allocate a previous enlisted
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* balloon pages before definetively releasing it back to the guest system.
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* balloon pages before definitively releasing it back to the guest system.
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* This function tries to remove @n_req_pages from the ballooned pages and
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* return them to the caller in the @pages list.
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*
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* Note that this function may fail to dequeue some pages temporarily empty due
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* to compaction isolated pages.
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* Note that this function may fail to dequeue some pages even if the balloon
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* isn't empty - since the page list can be temporarily empty due to compaction
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* of isolated pages.
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*
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* Return: number of pages that were added to the @pages list.
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*/
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@ -112,12 +113,13 @@ EXPORT_SYMBOL_GPL(balloon_page_list_dequeue);
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/*
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* balloon_page_alloc - allocates a new page for insertion into the balloon
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* page list.
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* page list.
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*
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* Driver must call it to properly allocate a new enlisted balloon page.
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* Driver must call balloon_page_enqueue before definitively removing it from
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* the guest system. This function returns the page address for the recently
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* allocated page or NULL in the case we fail to allocate a new page this turn.
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* Driver must call this function to properly allocate a new balloon page.
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* Driver must call balloon_page_enqueue before definitively removing the page
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* from the guest system.
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*
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* Return: struct page for the allocated page or NULL on allocation failure.
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*/
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struct page *balloon_page_alloc(void)
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{
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@ -130,19 +132,15 @@ EXPORT_SYMBOL_GPL(balloon_page_alloc);
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/*
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* balloon_page_enqueue - inserts a new page into the balloon page list.
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*
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* @b_dev_info: balloon device descriptor where we will insert a new page to
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* @b_dev_info: balloon device descriptor where we will insert a new page
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* @page: new page to enqueue - allocated using balloon_page_alloc.
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*
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* Driver must call it to properly enqueue a new allocated balloon page
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* before definitively removing it from the guest system.
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* Drivers must call this function to properly enqueue a new allocated balloon
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* page before definitively removing the page from the guest system.
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*
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* Drivers must not call balloon_page_enqueue on pages that have been
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* pushed to a list with balloon_page_push before removing them with
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* balloon_page_pop. To all pages on a list, use balloon_page_list_enqueue
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* instead.
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*
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* This function returns the page address for the recently enqueued page or
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* NULL in the case we fail to allocate a new page this turn.
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* Drivers must not call balloon_page_enqueue on pages that have been pushed to
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* a list with balloon_page_push before removing them with balloon_page_pop. To
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* enqueue a list of pages, use balloon_page_list_enqueue instead.
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*/
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void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
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struct page *page)
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@ -157,14 +155,23 @@ EXPORT_SYMBOL_GPL(balloon_page_enqueue);
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/*
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* balloon_page_dequeue - removes a page from balloon's page list and returns
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* the its address to allow the driver release the page.
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* its address to allow the driver to release the page.
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* @b_dev_info: balloon device decriptor where we will grab a page from.
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*
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* Driver must call it to properly de-allocate a previous enlisted balloon page
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* before definetively releasing it back to the guest system.
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* This function returns the page address for the recently dequeued page or
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* NULL in the case we find balloon's page list temporarily empty due to
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* compaction isolated pages.
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* Driver must call this function to properly dequeue a previously enqueued page
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* before definitively releasing it back to the guest system.
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*
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* Caller must perform its own accounting to ensure that this
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* function is called only if some pages are actually enqueued.
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*
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* Note that this function may fail to dequeue some pages even if there are
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* some enqueued pages - since the page list can be temporarily empty due to
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* the compaction of isolated pages.
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*
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* TODO: remove the caller accounting requirements, and allow caller to wait
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* until all pages can be dequeued.
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*
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* Return: struct page for the dequeued page, or NULL if no page was dequeued.
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*/
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struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
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{
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@ -177,9 +184,9 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
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if (n_pages != 1) {
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/*
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* If we are unable to dequeue a balloon page because the page
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* list is empty and there is no isolated pages, then something
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* list is empty and there are no isolated pages, then something
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* went out of track and some balloon pages are lost.
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* BUG() here, otherwise the balloon driver may get stuck into
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* BUG() here, otherwise the balloon driver may get stuck in
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* an infinite loop while attempting to release all its pages.
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*/
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spin_lock_irqsave(&b_dev_info->pages_lock, flags);
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@ -230,8 +237,8 @@ int balloon_page_migrate(struct address_space *mapping,
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/*
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* We can not easily support the no copy case here so ignore it as it
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* is unlikely to be use with ballon pages. See include/linux/hmm.h for
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* user of the MIGRATE_SYNC_NO_COPY mode.
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* is unlikely to be used with balloon pages. See include/linux/hmm.h
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* for a user of the MIGRATE_SYNC_NO_COPY mode.
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*/
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if (mode == MIGRATE_SYNC_NO_COPY)
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return -EINVAL;
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