From: Lee Schermerhorn Christoph Lameter pointed out that ram disk pages also clutter the LRU lists. When vmscan finds them dirty and tries to clean them, the ram disk writeback function just redirties the page so that it goes back onto the active list. Round and round she goes... Define new address_space flag [shares address_space flags member with mapping's gfp mask] to indicate that the address space contains all unevictable pages. This will provide for efficient testing of ramdisk pages in page_evictable(). Also provide wrapper functions to set/test the unevictable state to minimize #ifdefs in ramdisk driver and any other users of this facility. Set the unevictable state on address_space structures for new ramdisk inodes. Test the unevictable state in page_evictable() to cull unevictable pages. Similarly, ramfs pages are unevictable. Set the 'unevictable' address_space flag for new ramfs inodes. These changes depend on [CONFIG_]UNEVICTABLE_LRU. Signed-off-by: Lee Schermerhorn Signed-off-by: Rik van Riel drivers/block/brd.c | 13 +++++++++++++ fs/ramfs/inode.c | 1 + include/linux/pagemap.h | 22 ++++++++++++++++++++++ mm/vmscan.c | 5 +++++ 4 files changed, 41 insertions(+) Index: linux-2.6.26-rc5-mm2/include/linux/pagemap.h =================================================================== --- linux-2.6.26-rc5-mm2.orig/include/linux/pagemap.h 2008-06-10 10:46:23.000000000 -0400 +++ linux-2.6.26-rc5-mm2/include/linux/pagemap.h 2008-06-10 16:47:23.000000000 -0400 @@ -30,6 +30,28 @@ static inline void mapping_set_error(str } } +#ifdef CONFIG_UNEVICTABLE_LRU +#define AS_UNEVICTABLE (__GFP_BITS_SHIFT + 2) /* e.g., ramdisk, SHM_LOCK */ + +static inline void mapping_set_unevictable(struct address_space *mapping) +{ + set_bit(AS_UNEVICTABLE, &mapping->flags); +} + +static inline int mapping_unevictable(struct address_space *mapping) +{ + if (mapping && (mapping->flags & AS_UNEVICTABLE)) + return 1; + return 0; +} +#else +static inline void mapping_set_unevictable(struct address_space *mapping) { } +static inline int mapping_unevictable(struct address_space *mapping) +{ + return 0; +} +#endif + static inline gfp_t mapping_gfp_mask(struct address_space * mapping) { return (__force gfp_t)mapping->flags & __GFP_BITS_MASK; Index: linux-2.6.26-rc5-mm2/mm/vmscan.c =================================================================== --- linux-2.6.26-rc5-mm2.orig/mm/vmscan.c 2008-06-10 16:25:49.000000000 -0400 +++ linux-2.6.26-rc5-mm2/mm/vmscan.c 2008-06-10 16:47:23.000000000 -0400 @@ -2320,6 +2320,8 @@ int zone_reclaim(struct zone *zone, gfp_ * lists vs unevictable list. * * Reasons page might not be evictable: + * (1) page's mapping marked unevictable + * * TODO - later patches */ int page_evictable(struct page *page, struct vm_area_struct *vma) @@ -2327,6 +2329,9 @@ int page_evictable(struct page *page, st VM_BUG_ON(PageUnevictable(page)); + if (mapping_unevictable(page_mapping(page))) + return 0; + /* TODO: test page [!]evictable conditions */ return 1; Index: linux-2.6.26-rc5-mm2/fs/ramfs/inode.c =================================================================== --- linux-2.6.26-rc5-mm2.orig/fs/ramfs/inode.c 2008-06-10 10:25:06.000000000 -0400 +++ linux-2.6.26-rc5-mm2/fs/ramfs/inode.c 2008-06-10 16:47:23.000000000 -0400 @@ -61,6 +61,7 @@ struct inode *ramfs_get_inode(struct sup inode->i_mapping->a_ops = &ramfs_aops; inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info; mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); + mapping_set_unevictable(inode->i_mapping); inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; switch (mode & S_IFMT) { default: Index: linux-2.6.26-rc5-mm2/drivers/block/brd.c =================================================================== --- linux-2.6.26-rc5-mm2.orig/drivers/block/brd.c 2008-06-10 10:46:18.000000000 -0400 +++ linux-2.6.26-rc5-mm2/drivers/block/brd.c 2008-06-10 16:47:23.000000000 -0400 @@ -374,8 +374,21 @@ static int brd_ioctl(struct inode *inode return error; } +/* + * brd_open(): + * Just mark the mapping as containing unevictable pages + */ +static int brd_open(struct inode *inode, struct file *filp) +{ + struct address_space *mapping = inode->i_mapping; + + mapping_set_unevictable(mapping); + return 0; +} + static struct block_device_operations brd_fops = { .owner = THIS_MODULE, + .open = brd_open, .ioctl = brd_ioctl, #ifdef CONFIG_BLK_DEV_XIP .direct_access = brd_direct_access, -- 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/