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memcg: move charges of anonymous swap

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This patch is another core part of this move-charge-at-task-migration
feature.  It enables moving charges of anonymous swaps.

To move the charge of swap, we need to exchange swap_cgroup's record.

In current implementation, swap_cgroup's record is protected by:

  - page lock: if the entry is on swap cache.
  - swap_lock: if the entry is not on swap cache.

This works well in usual swap-in/out activity.

But this behavior make the feature of moving swap charge check many
conditions to exchange swap_cgroup's record safely.

So I changed modification of swap_cgroup's recored(swap_cgroup_record())
to use xchg, and define a new function to cmpxchg swap_cgroup's record.

This patch also enables moving charge of non pte_present but not uncharged
swap caches, which can be exist on swap-out path, by getting the target
pages via find_get_page() as do_mincore() does.

[[email protected]: fix ia64 build]
[[email protected]: fix typos]
Signed-off-by: Daisuke Nishimura <[email protected]>
Cc: Balbir Singh <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Paul Menage <[email protected]>
Cc: Daisuke Nishimura <[email protected]>
Signed-off-by: KOSAKI Motohiro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Daisuke Nishimura 2010-03-10 15:22:17 -08:00 • committed by Linus Torvalds
commit 024914477e
6 changed files with 223 additions and 38 deletions
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31
mm/swapfile.c
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@ -723,6 +723,37 @@ int free_swap_and_cache(swp_entry_t entry)
return p != NULL;
}
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
/**
* mem_cgroup_count_swap_user - count the user of a swap entry
* @ent: the swap entry to be checked
* @pagep: the pointer for the swap cache page of the entry to be stored
*
* Returns the number of the user of the swap entry. The number is valid only
* for swaps of anonymous pages.
* If the entry is found on swap cache, the page is stored to pagep with
* refcount of it being incremented.
*/
int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
{
struct page *page;
struct swap_info_struct *p;
int count = 0;
page = find_get_page(&swapper_space, ent.val);
if (page)
count += page_mapcount(page);
p = swap_info_get(ent);
if (p) {
count += swap_count(p->swap_map[swp_offset(ent)]);
spin_unlock(&swap_lock);
}
*pagep = page;
return count;
}
#endif
#ifdef CONFIG_HIBERNATION
/*
* Find the swap type that corresponds to given device (if any).