diff options
| -rw-r--r-- | mm/vmscan.c | 68 |
1 files changed, 60 insertions, 8 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 99ec7fa..a6e65d0 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -271,6 +271,12 @@ static void handle_write_error(struct address_space *mapping, unlock_page(page); } +/* Request for sync pageout. */ +enum pageout_io { + PAGEOUT_IO_ASYNC, + PAGEOUT_IO_SYNC, +}; + /* possible outcome of pageout() */ typedef enum { /* failed to write page out, page is locked */ @@ -287,7 +293,8 @@ typedef enum { * pageout is called by shrink_page_list() for each dirty page. * Calls ->writepage(). */ -static pageout_t pageout(struct page *page, struct address_space *mapping) +static pageout_t pageout(struct page *page, struct address_space *mapping, + enum pageout_io sync_writeback) { /* * If the page is dirty, only perform writeback if that write @@ -346,6 +353,15 @@ static pageout_t pageout(struct page *page, struct address_space *mapping) ClearPageReclaim(page); return PAGE_ACTIVATE; } + + /* + * Wait on writeback if requested to. This happens when + * direct reclaiming a large contiguous area and the + * first attempt to free a range of pages fails. + */ + if (PageWriteback(page) && sync_writeback == PAGEOUT_IO_SYNC) + wait_on_page_writeback(page); + if (!PageWriteback(page)) { /* synchronous write or broken a_ops? */ ClearPageReclaim(page); @@ -423,7 +439,8 @@ cannot_free: * shrink_page_list() returns the number of reclaimed pages */ static unsigned long shrink_page_list(struct list_head *page_list, - struct scan_control *sc) + struct scan_control *sc, + enum pageout_io sync_writeback) { LIST_HEAD(ret_pages); struct pagevec freed_pvec; @@ -458,8 +475,23 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (page_mapped(page) || PageSwapCache(page)) sc->nr_scanned++; - if (PageWriteback(page)) - goto keep_locked; + may_enter_fs = (sc->gfp_mask & __GFP_FS) || + (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); + + if (PageWriteback(page)) { + /* + * Synchronous reclaim is performed in two passes, + * first an asynchronous pass over the list to + * start parallel writeback, and a second synchronous + * pass to wait for the IO to complete. Wait here + * for any page for which writeback has already + * started. + */ + if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs) + wait_on_page_writeback(page); + else + goto keep_locked; + } referenced = page_referenced(page, 1); /* In active use or really unfreeable? Activate it. */ @@ -478,8 +510,6 @@ static unsigned long shrink_page_list(struct list_head *page_list, #endif /* CONFIG_SWAP */ mapping = page_mapping(page); - may_enter_fs = (sc->gfp_mask & __GFP_FS) || - (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO)); /* * The page is mapped into the page tables of one or more @@ -505,7 +535,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, goto keep_locked; /* Page is dirty, try to write it out here */ - switch(pageout(page, mapping)) { + switch (pageout(page, mapping, sync_writeback)) { case PAGE_KEEP: goto keep_locked; case PAGE_ACTIVATE: @@ -786,7 +816,29 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, spin_unlock_irq(&zone->lru_lock); nr_scanned += nr_scan; - nr_freed = shrink_page_list(&page_list, sc); + nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC); + + /* + * If we are direct reclaiming for contiguous pages and we do + * not reclaim everything in the list, try again and wait + * for IO to complete. This will stall high-order allocations + * but that should be acceptable to the caller + */ + if (nr_freed < nr_taken && !current_is_kswapd() && + sc->order > PAGE_ALLOC_COSTLY_ORDER) { + congestion_wait(WRITE, HZ/10); + + /* + * The attempt at page out may have made some + * of the pages active, mark them inactive again. + */ + nr_active = clear_active_flags(&page_list); + count_vm_events(PGDEACTIVATE, nr_active); + + nr_freed += shrink_page_list(&page_list, sc, + PAGEOUT_IO_SYNC); + } + nr_reclaimed += nr_freed; local_irq_disable(); if (current_is_kswapd()) { |
