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balloon: fix up comments

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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>
This commit is contained in:
Michael S. Tsirkin 2019-07-18 08:19:24 -04:00
parent dd42290679
commit cfe61801b0
1 changed files with 37 additions and 30 deletions
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65
mm/balloon_compaction.c
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@ -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;