mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-06 02:24:14 +08:00
f0953a1bba
Fix ~94 single-word typos in locking code comments, plus a few very obvious grammar mistakes. Link: https://lkml.kernel.org/r/20210322212624.GA1963421@gmail.com Link: https://lore.kernel.org/r/20210322205203.GB1959563@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
261 lines
8.2 KiB
C
261 lines
8.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* mm/balloon_compaction.c
|
|
*
|
|
* Common interface for making balloon pages movable by compaction.
|
|
*
|
|
* Copyright (C) 2012, Red Hat, Inc. Rafael Aquini <aquini@redhat.com>
|
|
*/
|
|
#include <linux/mm.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/export.h>
|
|
#include <linux/balloon_compaction.h>
|
|
|
|
static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
|
|
struct page *page)
|
|
{
|
|
/*
|
|
* Block others from accessing the 'page' when we get around to
|
|
* establishing additional references. We should be the only one
|
|
* holding a reference to the 'page' at this point. If we are not, then
|
|
* memory corruption is possible and we should stop execution.
|
|
*/
|
|
BUG_ON(!trylock_page(page));
|
|
balloon_page_insert(b_dev_info, page);
|
|
unlock_page(page);
|
|
__count_vm_event(BALLOON_INFLATE);
|
|
}
|
|
|
|
/**
|
|
* balloon_page_list_enqueue() - inserts a list of pages into the balloon page
|
|
* list.
|
|
* @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 this function to properly enqueue balloon pages before
|
|
* definitively removing them from the guest system.
|
|
*
|
|
* Return: number of pages that were enqueued.
|
|
*/
|
|
size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
|
|
struct list_head *pages)
|
|
{
|
|
struct page *page, *tmp;
|
|
unsigned long flags;
|
|
size_t n_pages = 0;
|
|
|
|
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++;
|
|
}
|
|
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
|
|
return n_pages;
|
|
}
|
|
EXPORT_SYMBOL_GPL(balloon_page_list_enqueue);
|
|
|
|
/**
|
|
* balloon_page_list_dequeue() - removes pages from balloon's page list and
|
|
* returns a list of the pages.
|
|
* @b_dev_info: balloon device descriptor where we will grab a page from.
|
|
* @pages: pointer to the list of pages that would be returned to the caller.
|
|
* @n_req_pages: number of requested pages.
|
|
*
|
|
* Driver must call this function to properly de-allocate a previous enlisted
|
|
* 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 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.
|
|
*/
|
|
size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
|
|
struct list_head *pages, size_t n_req_pages)
|
|
{
|
|
struct page *page, *tmp;
|
|
unsigned long flags;
|
|
size_t n_pages = 0;
|
|
|
|
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
|
|
list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
|
|
if (n_pages == n_req_pages)
|
|
break;
|
|
|
|
/*
|
|
* Block others from accessing the 'page' while we get around to
|
|
* establishing additional references and preparing the 'page'
|
|
* to be released by the balloon driver.
|
|
*/
|
|
if (!trylock_page(page))
|
|
continue;
|
|
|
|
if (IS_ENABLED(CONFIG_BALLOON_COMPACTION) &&
|
|
PageIsolated(page)) {
|
|
/* raced with isolation */
|
|
unlock_page(page);
|
|
continue;
|
|
}
|
|
balloon_page_delete(page);
|
|
__count_vm_event(BALLOON_DEFLATE);
|
|
list_add(&page->lru, pages);
|
|
unlock_page(page);
|
|
n_pages++;
|
|
}
|
|
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
|
|
|
|
return n_pages;
|
|
}
|
|
EXPORT_SYMBOL_GPL(balloon_page_list_dequeue);
|
|
|
|
/*
|
|
* balloon_page_alloc - allocates a new page for insertion into the balloon
|
|
* page list.
|
|
*
|
|
* 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)
|
|
{
|
|
struct page *page = alloc_page(balloon_mapping_gfp_mask() |
|
|
__GFP_NOMEMALLOC | __GFP_NORETRY |
|
|
__GFP_NOWARN);
|
|
return page;
|
|
}
|
|
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
|
|
* @page: new page to enqueue - allocated using balloon_page_alloc.
|
|
*
|
|
* 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
|
|
* 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)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
|
|
balloon_page_enqueue_one(b_dev_info, page);
|
|
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(balloon_page_enqueue);
|
|
|
|
/*
|
|
* balloon_page_dequeue - removes a page from balloon's page list and returns
|
|
* its address to allow the driver to release the page.
|
|
* @b_dev_info: balloon device descriptor where we will grab a page from.
|
|
*
|
|
* 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)
|
|
{
|
|
unsigned long flags;
|
|
LIST_HEAD(pages);
|
|
int n_pages;
|
|
|
|
n_pages = balloon_page_list_dequeue(b_dev_info, &pages, 1);
|
|
|
|
if (n_pages != 1) {
|
|
/*
|
|
* If we are unable to dequeue a balloon page because the page
|
|
* 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 in
|
|
* an infinite loop while attempting to release all its pages.
|
|
*/
|
|
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
|
|
if (unlikely(list_empty(&b_dev_info->pages) &&
|
|
!b_dev_info->isolated_pages))
|
|
BUG();
|
|
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
|
|
return NULL;
|
|
}
|
|
return list_first_entry(&pages, struct page, lru);
|
|
}
|
|
EXPORT_SYMBOL_GPL(balloon_page_dequeue);
|
|
|
|
#ifdef CONFIG_BALLOON_COMPACTION
|
|
|
|
bool balloon_page_isolate(struct page *page, isolate_mode_t mode)
|
|
|
|
{
|
|
struct balloon_dev_info *b_dev_info = balloon_page_device(page);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
|
|
list_del(&page->lru);
|
|
b_dev_info->isolated_pages++;
|
|
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
|
|
|
|
return true;
|
|
}
|
|
|
|
void balloon_page_putback(struct page *page)
|
|
{
|
|
struct balloon_dev_info *b_dev_info = balloon_page_device(page);
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
|
|
list_add(&page->lru, &b_dev_info->pages);
|
|
b_dev_info->isolated_pages--;
|
|
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
|
|
}
|
|
|
|
|
|
/* move_to_new_page() counterpart for a ballooned page */
|
|
int balloon_page_migrate(struct address_space *mapping,
|
|
struct page *newpage, struct page *page,
|
|
enum migrate_mode mode)
|
|
{
|
|
struct balloon_dev_info *balloon = balloon_page_device(page);
|
|
|
|
/*
|
|
* We can not easily support the no copy case here so ignore it as it
|
|
* 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;
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
|
|
|
|
return balloon->migratepage(balloon, newpage, page, mode);
|
|
}
|
|
|
|
const struct address_space_operations balloon_aops = {
|
|
.migratepage = balloon_page_migrate,
|
|
.isolate_page = balloon_page_isolate,
|
|
.putback_page = balloon_page_putback,
|
|
};
|
|
EXPORT_SYMBOL_GPL(balloon_aops);
|
|
|
|
#endif /* CONFIG_BALLOON_COMPACTION */
|