From: Lee Schermerhorn While working with Nick Piggin's mlock patches, I noticed that shmem segments locked via shmctl(SHM_LOCKED) were not being handled. SHM_LOCKed pages work like ramdisk pages--the writeback function just redirties the page so that it can't be reclaimed. Deal with these using the same approach as for ram disk pages. Use the AS_NORECLAIM flag to mark address_space of SHM_LOCKed shared memory regions as non-reclaimable. Then these pages will be culled off the normal LRU lists during vmscan. Add new wrapper function to clear the mapping's noreclaim state when/if shared memory segment is munlocked. Add 'scan_mapping_noreclaim_page()' to mm/vmscan.c to scan all pages in the shmem segment's mapping [struct address_space] for reclaimability now that they're no longer locked. If so, move them to the appropriate zone lru list. Changes depend on [CONFIG_]NORECLAIM_LRU. Signed-off-by: Lee Schermerhorn Signed-off-by: Rik van Riel --- V2 -> V3: + rebase to 23-mm1 atop RvR's split LRU series. + Use scan_mapping_noreclaim_page() on unlock. See below. V1 -> V2: + modify to use reworked 'scan_all_zones_noreclaim_pages()' See 'TODO' below - still pending. include/linux/pagemap.h | 10 ++++- include/linux/swap.h | 4 ++ mm/shmem.c | 3 + mm/vmscan.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 100 insertions(+), 2 deletions(-) Index: linux-2.6.26-rc2-mm1/mm/shmem.c =================================================================== --- linux-2.6.26-rc2-mm1.orig/mm/shmem.c 2008-05-16 13:31:54.000000000 -0400 +++ linux-2.6.26-rc2-mm1/mm/shmem.c 2008-05-16 14:05:23.000000000 -0400 @@ -1469,10 +1469,13 @@ int shmem_lock(struct file *file, int lo if (!user_shm_lock(inode->i_size, user)) goto out_nomem; info->flags |= VM_LOCKED; + mapping_set_noreclaim(file->f_mapping); } if (!lock && (info->flags & VM_LOCKED) && user) { user_shm_unlock(inode->i_size, user); info->flags &= ~VM_LOCKED; + mapping_clear_noreclaim(file->f_mapping); + scan_mapping_noreclaim_pages(file->f_mapping); } retval = 0; out_nomem: Index: linux-2.6.26-rc2-mm1/include/linux/pagemap.h =================================================================== --- linux-2.6.26-rc2-mm1.orig/include/linux/pagemap.h 2008-05-16 14:05:19.000000000 -0400 +++ linux-2.6.26-rc2-mm1/include/linux/pagemap.h 2008-05-16 14:05:23.000000000 -0400 @@ -38,14 +38,20 @@ static inline void mapping_set_noreclaim set_bit(AS_NORECLAIM, &mapping->flags); } +static inline void mapping_clear_noreclaim(struct address_space *mapping) +{ + clear_bit(AS_NORECLAIM, &mapping->flags); +} + static inline int mapping_non_reclaimable(struct address_space *mapping) { - if (mapping && (mapping->flags & AS_NORECLAIM)) - return 1; + if (mapping) + return test_bit(AS_NORECLAIM, &mapping->flags); return 0; } #else static inline void mapping_set_noreclaim(struct address_space *mapping) { } +static inline void mapping_clear_noreclaim(struct address_space *mapping) { } static inline int mapping_non_reclaimable(struct address_space *mapping) { return 0; Index: linux-2.6.26-rc2-mm1/mm/vmscan.c =================================================================== --- linux-2.6.26-rc2-mm1.orig/mm/vmscan.c 2008-05-16 14:05:19.000000000 -0400 +++ linux-2.6.26-rc2-mm1/mm/vmscan.c 2008-05-16 14:05:23.000000000 -0400 @@ -2274,4 +2274,89 @@ int page_reclaimable(struct page *page, return 1; } + +/** + * check_move_noreclaim_page - check page for reclaimability and move to appropriate zone lru list + * @page: page to check reclaimability and move to appropriate lru list + * @zone: zone page is in + * + * Checks a page for reclaimability and moves the page to the appropriate + * zone lru list. + * + * Restrictions: zone->lru_lock must be held, page must be on LRU and must + * have PageNoreclaim set. + */ +static void check_move_noreclaim_page(struct page *page, struct zone *zone) +{ + + ClearPageNoreclaim(page); /* for page_reclaimable() */ + if (page_reclaimable(page, NULL)) { + enum lru_list l = LRU_INACTIVE_ANON + page_file_cache(page); + __dec_zone_state(zone, NR_NORECLAIM); + list_move(&page->lru, &zone->list[l]); + __inc_zone_state(zone, NR_INACTIVE_ANON + l); + } else { + /* + * rotate noreclaim list + */ + SetPageNoreclaim(page); + list_move(&page->lru, &zone->list[LRU_NORECLAIM]); + } +} + +/** + * scan_mapping_noreclaim_pages - scan an address space for reclaimable pages + * @mapping: struct address_space to scan for reclaimable pages + * + * Scan all pages in mapping. Check non-reclaimable pages for + * reclaimability and move them to the appropriate zone lru list. + */ +void scan_mapping_noreclaim_pages(struct address_space *mapping) +{ + pgoff_t next = 0; + pgoff_t end = i_size_read(mapping->host); + struct zone *zone; + struct pagevec pvec; + + if (mapping->nrpages == 0) + return; + + pagevec_init(&pvec, 0); + while (next < end && + pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { + int i; + + zone = NULL; + + for (i = 0; i < pagevec_count(&pvec); i++) { + struct page *page = pvec.pages[i]; + pgoff_t page_index = page->index; + struct zone *pagezone = page_zone(page); + + if (page_index > next) + next = page_index; + next++; + + if (TestSetPageLocked(page)) + continue; + + if (pagezone != zone) { + if (zone) + spin_unlock(&zone->lru_lock); + zone = pagezone; + spin_lock(&zone->lru_lock); + } + + if (PageLRU(page) && PageNoreclaim(page)) + check_move_noreclaim_page(page, zone); + + unlock_page(page); + + } + if (zone) + spin_unlock(&zone->lru_lock); + pagevec_release(&pvec); + } + +} #endif Index: linux-2.6.26-rc2-mm1/include/linux/swap.h =================================================================== --- linux-2.6.26-rc2-mm1.orig/include/linux/swap.h 2008-05-16 14:05:09.000000000 -0400 +++ linux-2.6.26-rc2-mm1/include/linux/swap.h 2008-05-16 14:05:23.000000000 -0400 @@ -242,12 +242,16 @@ static inline int zone_reclaim(struct zo #ifdef CONFIG_NORECLAIM_LRU extern int page_reclaimable(struct page *page, struct vm_area_struct *vma); +extern void scan_mapping_noreclaim_pages(struct address_space *); #else static inline int page_reclaimable(struct page *page, struct vm_area_struct *vma) { return 1; } +static inline void scan_mapping_noreclaim_pages(struct address_space *mapping) +{ +} #endif extern int kswapd_run(int nid); -- All Rights Reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/