Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030739AbWK3RHv (ORCPT ); Thu, 30 Nov 2006 12:07:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030745AbWK3RHv (ORCPT ); Thu, 30 Nov 2006 12:07:51 -0500 Received: from calculon.skynet.ie ([193.1.99.88]:3001 "EHLO calculon.skynet.ie") by vger.kernel.org with ESMTP id S1030739AbWK3RHt (ORCPT ); Thu, 30 Nov 2006 12:07:49 -0500 Date: Thu, 30 Nov 2006 17:07:46 +0000 To: akpm@osdl.org Cc: clameter@sgi.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] Add __GFP_MOVABLE for callers to flag allocations that may be migrated Message-ID: <20061130170746.GA11363@skynet.ie> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline User-Agent: Mutt/1.5.9i From: mel@skynet.ie (Mel Gorman) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 17130 Lines: 318 Am reporting this patch after there were no further comments on the last version. It is often known at allocation time when a page may be migrated or not. This page adds a flag called __GFP_MOVABLE and GFP_HIGH_MOVABLE. Allocations using the __GFP_MOVABLE can be either migrated using the page migration mechanism or reclaimed by syncing with backing storage and discarding. Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the concept. Credit to Hugh Dickens for catching issues with shmem swap vector and ramfs allocations. Signed-off-by: Mel Gorman diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/fs/compat.c linux-2.6.19-rc6-mm2-mark_highmovable/fs/compat.c --- linux-2.6.19-rc6-mm2-clean/fs/compat.c 2006-11-29 10:31:09.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/fs/compat.c 2006-11-29 10:34:12.000000000 +0000 @@ -1419,7 +1419,7 @@ static int compat_copy_strings(int argc, page = bprm->page[i]; new = 0; if (!page) { - page = alloc_page(GFP_HIGHUSER); + page = alloc_page(GFP_HIGH_MOVABLE); bprm->page[i] = page; if (!page) { ret = -ENOMEM; diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/fs/exec.c linux-2.6.19-rc6-mm2-mark_highmovable/fs/exec.c --- linux-2.6.19-rc6-mm2-clean/fs/exec.c 2006-11-29 10:31:09.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/fs/exec.c 2006-11-29 10:34:12.000000000 +0000 @@ -239,7 +239,7 @@ static int copy_strings(int argc, char _ page = bprm->page[i]; new = 0; if (!page) { - page = alloc_page(GFP_HIGHUSER); + page = alloc_page(GFP_HIGH_MOVABLE); bprm->page[i] = page; if (!page) { ret = -ENOMEM; diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/fs/inode.c linux-2.6.19-rc6-mm2-mark_highmovable/fs/inode.c --- linux-2.6.19-rc6-mm2-clean/fs/inode.c 2006-11-29 10:31:09.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/fs/inode.c 2006-11-29 10:34:12.000000000 +0000 @@ -146,7 +146,7 @@ static struct inode *alloc_inode(struct mapping->a_ops = &empty_aops; mapping->host = inode; mapping->flags = 0; - mapping_set_gfp_mask(mapping, GFP_HIGHUSER); + mapping_set_gfp_mask(mapping, GFP_HIGH_MOVABLE); mapping->assoc_mapping = NULL; mapping->backing_dev_info = &default_backing_dev_info; diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/fs/ramfs/inode.c linux-2.6.19-rc6-mm2-mark_highmovable/fs/ramfs/inode.c --- linux-2.6.19-rc6-mm2-clean/fs/ramfs/inode.c 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/fs/ramfs/inode.c 2006-11-29 10:34:12.000000000 +0000 @@ -61,6 +61,7 @@ struct inode *ramfs_get_inode(struct sup inode->i_blocks = 0; 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); inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; switch (mode & S_IFMT) { default: diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-alpha/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-alpha/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-alpha/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-alpha/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -17,7 +17,7 @@ extern void clear_page(void *page); #define clear_user_page(page, vaddr, pg) clear_page(page) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vmaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE | __GFP_ZERO, vma, vmaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE extern void copy_page(void * _to, void * _from); diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-cris/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-cris/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-cris/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-cris/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -20,7 +20,7 @@ #define clear_user_page(page, vaddr, pg) clear_page(page) #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE | __GFP_ZERO, vma, vaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /* diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-h8300/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-h8300/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-h8300/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-h8300/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -22,7 +22,7 @@ #define clear_user_page(page, vaddr, pg) clear_page(page) #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE | __GFP_ZERO, vma, vaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /* diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-i386/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-i386/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-i386/page.h 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-i386/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -35,7 +35,7 @@ #define clear_user_page(page, vaddr, pg) clear_page(page) #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE|__GFP_ZERO, vma, vaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /* diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-ia64/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-ia64/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-ia64/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-ia64/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -89,7 +89,7 @@ do { \ #define alloc_zeroed_user_highpage(vma, vaddr) \ ({ \ - struct page *page = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr); \ + struct page *page = alloc_page_vma(GFP_HIGH_MOVABLE | __GFP_ZERO, vma, vaddr); \ if (page) \ flush_dcache_page(page); \ page; \ diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-m32r/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-m32r/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-m32r/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-m32r/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -16,7 +16,7 @@ extern void copy_page(void *to, void *fr #define clear_user_page(page, vaddr, pg) clear_page(page) #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE | __GFP_ZERO, vma, vaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /* diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-s390/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-s390/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-s390/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-s390/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -64,7 +64,7 @@ static inline void copy_page(void *to, v #define clear_user_page(page, vaddr, pg) clear_page(page) #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE | __GFP_ZERO, vma, vaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /* diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/asm-x86_64/page.h linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-x86_64/page.h --- linux-2.6.19-rc6-mm2-clean/include/asm-x86_64/page.h 2006-11-16 04:03:40.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/asm-x86_64/page.h 2006-11-29 10:34:12.000000000 +0000 @@ -51,7 +51,7 @@ void copy_page(void *, void *); #define clear_user_page(page, vaddr, pg) clear_page(page) #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) -#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vma, vaddr) +#define alloc_zeroed_user_highpage(vma, vaddr) alloc_page_vma(GFP_HIGH_MOVABLE|__GFP_ZERO, vma, vaddr) #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE /* * These are used to make use of C type-checking.. diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/linux/gfp.h linux-2.6.19-rc6-mm2-mark_highmovable/include/linux/gfp.h --- linux-2.6.19-rc6-mm2-clean/include/linux/gfp.h 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/linux/gfp.h 2006-11-29 10:34:12.000000000 +0000 @@ -30,6 +30,9 @@ struct vm_area_struct; * cannot handle allocation failures. * * __GFP_NORETRY: The VM implementation must not retry indefinitely. + * + * __GFP_MOVABLE: Flag that this page will be movable by the page migration + * mechanism */ #define __GFP_WAIT ((__force gfp_t)0x10u) /* Can wait and reschedule? */ #define __GFP_HIGH ((__force gfp_t)0x20u) /* Should access emergency pools? */ @@ -46,6 +49,7 @@ struct vm_area_struct; #define __GFP_NOMEMALLOC ((__force gfp_t)0x10000u) /* Don't use emergency reserves */ #define __GFP_HARDWALL ((__force gfp_t)0x20000u) /* Enforce hardwall cpuset memory allocs */ #define __GFP_THISNODE ((__force gfp_t)0x40000u)/* No fallback, no policies */ +#define __GFP_MOVABLE ((__force gfp_t)0x80000u) /* Page is movable */ #define __GFP_BITS_SHIFT 20 /* Room for 20 __GFP_FOO bits */ #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) @@ -54,7 +58,8 @@ struct vm_area_struct; #define GFP_LEVEL_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS| \ __GFP_COLD|__GFP_NOWARN|__GFP_REPEAT| \ __GFP_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP| \ - __GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_THISNODE) + __GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_THISNODE|\ + __GFP_MOVABLE) /* This equals 0, but use constants in case they ever change */ #define GFP_NOWAIT (GFP_ATOMIC & ~__GFP_HIGH) @@ -66,6 +71,9 @@ struct vm_area_struct; #define GFP_USER (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL) #define GFP_HIGHUSER (__GFP_WAIT | __GFP_IO | __GFP_FS | __GFP_HARDWALL | \ __GFP_HIGHMEM) +#define GFP_HIGH_MOVABLE (__GFP_WAIT | __GFP_IO | __GFP_FS | \ + __GFP_HARDWALL | __GFP_HIGHMEM | \ + __GFP_MOVABLE) #ifdef CONFIG_NUMA #define GFP_THISNODE (__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY) diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/include/linux/highmem.h linux-2.6.19-rc6-mm2-mark_highmovable/include/linux/highmem.h --- linux-2.6.19-rc6-mm2-clean/include/linux/highmem.h 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/include/linux/highmem.h 2006-11-29 10:34:12.000000000 +0000 @@ -65,7 +65,7 @@ static inline void clear_user_highpage(s static inline struct page * alloc_zeroed_user_highpage(struct vm_area_struct *vma, unsigned long vaddr) { - struct page *page = alloc_page_vma(GFP_HIGHUSER, vma, vaddr); + struct page *page = alloc_page_vma(GFP_HIGH_MOVABLE, vma, vaddr); if (page) clear_user_highpage(page, vaddr); diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/mm/memory.c linux-2.6.19-rc6-mm2-mark_highmovable/mm/memory.c --- linux-2.6.19-rc6-mm2-clean/mm/memory.c 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/mm/memory.c 2006-11-29 10:34:12.000000000 +0000 @@ -1564,7 +1564,7 @@ gotten: if (!new_page) goto oom; } else { - new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); + new_page = alloc_page_vma(GFP_HIGH_MOVABLE, vma, address); if (!new_page) goto oom; cow_user_page(new_page, old_page, address); @@ -2188,7 +2188,7 @@ retry: if (unlikely(anon_vma_prepare(vma))) goto oom; - page = alloc_page_vma(GFP_HIGHUSER, vma, address); + page = alloc_page_vma(GFP_HIGH_MOVABLE, vma, address); if (!page) goto oom; copy_user_highpage(page, new_page, address); diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/mm/mempolicy.c linux-2.6.19-rc6-mm2-mark_highmovable/mm/mempolicy.c --- linux-2.6.19-rc6-mm2-clean/mm/mempolicy.c 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/mm/mempolicy.c 2006-11-29 10:34:12.000000000 +0000 @@ -598,7 +598,7 @@ static void migrate_page_add(struct page static struct page *new_node_page(struct page *page, unsigned long node, int **x) { - return alloc_pages_node(node, GFP_HIGHUSER, 0); + return alloc_pages_node(node, GFP_HIGH_MOVABLE, 0); } /* @@ -714,7 +714,7 @@ static struct page *new_vma_page(struct { struct vm_area_struct *vma = (struct vm_area_struct *)private; - return alloc_page_vma(GFP_HIGHUSER, vma, page_address_in_vma(page, vma)); + return alloc_page_vma(GFP_HIGH_MOVABLE, vma, page_address_in_vma(page, vma)); } #else diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/mm/migrate.c linux-2.6.19-rc6-mm2-mark_highmovable/mm/migrate.c --- linux-2.6.19-rc6-mm2-clean/mm/migrate.c 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/mm/migrate.c 2006-11-29 10:34:12.000000000 +0000 @@ -748,7 +748,7 @@ static struct page *new_page_node(struct *result = &pm->status; - return alloc_pages_node(pm->node, GFP_HIGHUSER | GFP_THISNODE, 0); + return alloc_pages_node(pm->node, GFP_HIGH_MOVABLE | GFP_THISNODE, 0); } /* diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/mm/shmem.c linux-2.6.19-rc6-mm2-mark_highmovable/mm/shmem.c --- linux-2.6.19-rc6-mm2-clean/mm/shmem.c 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/mm/shmem.c 2006-11-29 10:34:12.000000000 +0000 @@ -93,8 +93,11 @@ static inline struct page *shmem_dir_all * The above definition of ENTRIES_PER_PAGE, and the use of * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: * might be reconsidered if it ever diverges from PAGE_SIZE. + * + * __GFP_MOVABLE is masked out as swap vectors cannot move */ - return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); + return alloc_pages((gfp_mask & ~__GFP_MOVABLE) | __GFP_ZERO, + PAGE_CACHE_SHIFT-PAGE_SHIFT); } static inline void shmem_dir_free(struct page *page) @@ -372,7 +375,7 @@ static swp_entry_t *shmem_swp_alloc(stru } spin_unlock(&info->lock); - page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); + page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); if (page) set_page_private(page, 0); spin_lock(&info->lock); diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/mm/swap_prefetch.c linux-2.6.19-rc6-mm2-mark_highmovable/mm/swap_prefetch.c --- linux-2.6.19-rc6-mm2-clean/mm/swap_prefetch.c 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/mm/swap_prefetch.c 2006-11-29 10:34:12.000000000 +0000 @@ -204,7 +204,7 @@ static enum trickle_return trickle_swap_ * Get a new page to read from swap. We have already checked the * watermarks so __alloc_pages will not call on reclaim. */ - page = alloc_pages_node(node, GFP_HIGHUSER & ~__GFP_WAIT, 0); + page = alloc_pages_node(node, GFP_HIGH_MOVABLE & ~__GFP_WAIT, 0); if (unlikely(!page)) { ret = TRICKLE_DELAY; goto out; diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.19-rc6-mm2-clean/mm/swap_state.c linux-2.6.19-rc6-mm2-mark_highmovable/mm/swap_state.c --- linux-2.6.19-rc6-mm2-clean/mm/swap_state.c 2006-11-29 10:31:10.000000000 +0000 +++ linux-2.6.19-rc6-mm2-mark_highmovable/mm/swap_state.c 2006-11-29 10:34:12.000000000 +0000 @@ -343,7 +343,7 @@ struct page *read_swap_cache_async(swp_e * Get a new page to read into from swap. */ if (!new_page) { - new_page = alloc_page_vma(GFP_HIGHUSER, vma, addr); + new_page = alloc_page_vma(GFP_HIGH_MOVABLE, vma, addr); if (!new_page) break; /* Out of memory */ } - 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/