Messages in this thread | | | Date | Fri, 29 May 2009 14:08:32 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 1/4] add swap cache interface for swap reference |
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On Fri, 29 May 2009 13:21:53 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> On Thu, 28 May 2009 14:10:49 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > > > In following patch, usage of swap cache will be recorded into swap_map. > > This patch is for necessary interface changes to do that. > > > > 2 interfaces: > > - swapcache_prepare() > > - swapcache_free() > > is added for allocating/freeing refcnt from swap-cache to existing > > swap entries. But implementation itself is not changed under this patch. > > At adding swapcache_free(), memcg's hook code is moved under swapcache_free(). > > This is better than using scattered hooks. > > > IIUC, swap_free() at the end of shmem_writepage() should also be changed to swapcache_free(). > Hmm!. Oh, yes. shmem_writepage()'s error path. Thank you. It will be fixed.
Thanks, -Kame
> Thanks, > Daisuke Nishimura. > > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > > --- > > include/linux/swap.h | 7 +++++++ > > mm/swap_state.c | 11 +++++------ > > mm/swapfile.c | 19 +++++++++++++++++++ > > mm/vmscan.c | 3 +-- > > 4 files changed, 32 insertions(+), 8 deletions(-) > > > > Index: new-trial-swapcount2/include/linux/swap.h > > =================================================================== > > --- new-trial-swapcount2.orig/include/linux/swap.h > > +++ new-trial-swapcount2/include/linux/swap.h > > @@ -301,8 +301,10 @@ extern void si_swapinfo(struct sysinfo * > > extern swp_entry_t get_swap_page(void); > > extern swp_entry_t get_swap_page_of_type(int); > > extern int swap_duplicate(swp_entry_t); > > +extern int swapcache_prepare(swp_entry_t); > > extern int valid_swaphandles(swp_entry_t, unsigned long *); > > extern void swap_free(swp_entry_t); > > +extern void swapcache_free(swp_entry_t, struct page *page); > > extern int free_swap_and_cache(swp_entry_t); > > extern int swap_type_of(dev_t, sector_t, struct block_device **); > > extern unsigned int count_swap_pages(int, int); > > @@ -371,11 +373,16 @@ static inline void show_swap_cache_info( > > > > #define free_swap_and_cache(swp) is_migration_entry(swp) > > #define swap_duplicate(swp) is_migration_entry(swp) > > +#define swapcache_prepare(swp) is_migration_entry(swp) > > > > static inline void swap_free(swp_entry_t swp) > > { > > } > > > > +static inline void swapcache_free(swp_entry_t swp, struct page *page) > > +{ > > +} > > + > > static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, > > struct vm_area_struct *vma, unsigned long addr) > > { > > Index: new-trial-swapcount2/mm/swap_state.c > > =================================================================== > > --- new-trial-swapcount2.orig/mm/swap_state.c > > +++ new-trial-swapcount2/mm/swap_state.c > > @@ -162,11 +162,11 @@ int add_to_swap(struct page *page) > > return 1; > > case -EEXIST: > > /* Raced with "speculative" read_swap_cache_async */ > > - swap_free(entry); > > + swapcache_free(entry, NULL); > > continue; > > default: > > /* -ENOMEM radix-tree allocation failure */ > > - swap_free(entry); > > + swapcache_free(entry, NULL); > > return 0; > > } > > } > > @@ -188,8 +188,7 @@ void delete_from_swap_cache(struct page > > __delete_from_swap_cache(page); > > spin_unlock_irq(&swapper_space.tree_lock); > > > > - mem_cgroup_uncharge_swapcache(page, entry); > > - swap_free(entry); > > + swapcache_free(entry, page); > > page_cache_release(page); > > } > > > > @@ -293,7 +292,7 @@ struct page *read_swap_cache_async(swp_e > > /* > > * Swap entry may have been freed since our caller observed it. > > */ > > - if (!swap_duplicate(entry)) > > + if (!swapcache_prepare(entry)) > > break; > > > > /* > > @@ -317,7 +316,7 @@ struct page *read_swap_cache_async(swp_e > > } > > ClearPageSwapBacked(new_page); > > __clear_page_locked(new_page); > > - swap_free(entry); > > + swapcache_free(entry, NULL); > > } while (err != -ENOMEM); > > > > if (new_page) > > Index: new-trial-swapcount2/mm/swapfile.c > > =================================================================== > > --- new-trial-swapcount2.orig/mm/swapfile.c > > +++ new-trial-swapcount2/mm/swapfile.c > > @@ -510,6 +510,16 @@ void swap_free(swp_entry_t entry) > > } > > > > /* > > + * Called after dropping swapcache to decrease refcnt to swap entries. > > + */ > > +void swapcache_free(swp_entry_t entry, struct page *page) > > +{ > > + if (page) > > + mem_cgroup_uncharge_swapcache(page, entry); > > + return swap_free(entry); > > +} > > + > > +/* > > * How many references to page are currently swapped out? > > */ > > static inline int page_swapcount(struct page *page) > > @@ -1979,6 +1989,15 @@ bad_file: > > goto out; > > } > > > > +/* > > + * Called when allocating swap cache for exising swap entry, > > + */ > > +int swapcache_prepare(swp_entry_t entry) > > +{ > > + return swap_duplicate(entry); > > +} > > + > > + > > struct swap_info_struct * > > get_swap_info_struct(unsigned type) > > { > > Index: new-trial-swapcount2/mm/vmscan.c > > =================================================================== > > --- new-trial-swapcount2.orig/mm/vmscan.c > > +++ new-trial-swapcount2/mm/vmscan.c > > @@ -477,8 +477,7 @@ static int __remove_mapping(struct addre > > swp_entry_t swap = { .val = page_private(page) }; > > __delete_from_swap_cache(page); > > spin_unlock_irq(&mapping->tree_lock); > > - mem_cgroup_uncharge_swapcache(page, swap); > > - swap_free(swap); > > + swapcache_free(swap, page); > > } else { > > __remove_from_page_cache(page); > > spin_unlock_irq(&mapping->tree_lock); > > >
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