From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 3E2D46B004D for ; Fri, 29 May 2009 01:05:04 -0400 (EDT) Date: Fri, 29 May 2009 13:21:53 +0900 From: Daisuke Nishimura Subject: Re: [PATCH 1/4] add swap cache interface for swap reference Message-Id: <20090529132153.3a72f2c3.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20090528141049.cc45a116.kamezawa.hiroyu@jp.fujitsu.com> References: <20090528135455.0c83bedc.kamezawa.hiroyu@jp.fujitsu.com> <20090528141049.cc45a116.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "balbir@linux.vnet.ibm.com" , "hugh.dickins@tiscali.co.uk" , "hannes@cmpxchg.org" , "akpm@linux-foundation.org" , Daisuke Nishimura List-ID: On Thu, 28 May 2009 14:10:49 +0900, KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki > > 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(). Thanks, Daisuke Nishimura. > Signed-off-by: KAMEZAWA Hiroyuki > --- > 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); > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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