Export 9 page flags in /proc/kpageflags, and 8 more for kernel developers. 1) for kernel hackers (on CONFIG_DEBUG_KERNEL) - all available page flags are exported, and - exported as is 2) for admins and end users - only the more `well known' flags are exported: 11. KPF_MMAP (pseudo flag) memory mapped page 12. KPF_ANON (pseudo flag) memory mapped page (anonymous) 13. KPF_SWAPCACHE page is in swap cache 14. KPF_SWAPBACKED page is swap/RAM backed 15. KPF_COMPOUND_HEAD (*) 16. KPF_COMPOUND_TAIL (*) 17. KPF_UNEVICTABLE page is in the unevictable LRU list 18. KPF_HWPOISON hardware detected corruption 19. KPF_NOPAGE (pseudo flag) no page frame at the address (*) For compound pages, exporting _both_ head/tail info enables users to tell where a compound page starts/ends, and its order. - limit flags to their typical usage scenario, as indicated by KOSAKI: - LRU pages: only export relevant flags - PG_lru - PG_unevictable - PG_active - PG_referenced - page_mapped() - PageAnon() - PG_swapcache - PG_swapbacked - PG_reclaim - no-IO pages: mask out irrelevant flags - PG_dirty - PG_uptodate - PG_writeback - SLAB pages: mask out overloaded flags: - PG_error - PG_active - PG_private - PG_reclaim: mask out the overloaded PG_readahead - compound flags: only export huge/gigantic pages Here are the admin/linus views of all page flags on a newly booted nfs-root system: # ./page-types # for admin flags page-count MB symbolic-flags long-symbolic-flags 0x000000000000 491174 1918 ____________________________ 0x000000000020 1 0 _____l______________________ lru 0x000000000028 2543 9 ___U_l______________________ uptodate,lru 0x00000000002c 5288 20 __RU_l______________________ referenced,uptodate,lru 0x000000004060 1 0 _____lA_______b_____________ lru,active,swapbacked 0x000000004064 19 0 __R__lA_______b_____________ referenced,lru,active,swapbacked 0x000000000068 225 0 ___U_lA_____________________ uptodate,lru,active 0x00000000006c 969 3 __RU_lA_____________________ referenced,uptodate,lru,active 0x000000000080 6832 26 _______S____________________ slab 0x000000000400 576 2 __________B_________________ buddy 0x000000000828 1159 4 ___U_l_____M________________ uptodate,lru,mmap 0x00000000082c 310 1 __RU_l_____M________________ referenced,uptodate,lru,mmap 0x000000004860 2 0 _____lA____M__b_____________ lru,active,mmap,swapbacked 0x000000000868 375 1 ___U_lA____M________________ uptodate,lru,active,mmap 0x00000000086c 635 2 __RU_lA____M________________ referenced,uptodate,lru,active,mmap 0x000000005860 3831 14 _____lA____Ma_b_____________ lru,active,mmap,anonymous,swapbacked 0x000000005864 28 0 __R__lA____Ma_b_____________ referenced,lru,active,mmap,anonymous,swapbacked total 513968 2007 # ./page-types # for linus, when CONFIG_DEBUG_KERNEL is turned on flags page-count MB symbolic-flags long-symbolic-flags 0x000000000000 471058 1840 ____________________________ 0x000100000000 19288 75 ____________________r_______ reserved 0x000000010000 1064 4 ________________T___________ compound_tail 0x000000008000 1 0 _______________H____________ compound_head 0x000000008014 1 0 __R_D__________H____________ referenced,dirty,compound_head 0x000000010014 4 0 __R_D___________T___________ referenced,dirty,compound_tail 0x000000000020 1 0 _____l______________________ lru 0x000000000028 2522 9 ___U_l______________________ uptodate,lru 0x00000000002c 5207 20 __RU_l______________________ referenced,uptodate,lru 0x000000000068 203 0 ___U_lA_____________________ uptodate,lru,active 0x00000000006c 869 3 __RU_lA_____________________ referenced,uptodate,lru,active 0x000000004078 1 0 ___UDlA_______b_____________ uptodate,dirty,lru,active,swapbacked 0x00000000407c 19 0 __RUDlA_______b_____________ referenced,uptodate,dirty,lru,active,swapbacked 0x000000000080 5989 23 _______S____________________ slab 0x000000008080 778 3 _______S_______H____________ slab,compound_head 0x000000000228 44 0 ___U_l___I__________________ uptodate,lru,reclaim 0x00000000022c 39 0 __RU_l___I__________________ referenced,uptodate,lru,reclaim 0x000000000268 12 0 ___U_lA__I__________________ uptodate,lru,active,reclaim 0x00000000026c 44 0 __RU_lA__I__________________ referenced,uptodate,lru,active,reclaim 0x000000000400 550 2 __________B_________________ buddy 0x000000000804 1 0 __R________M________________ referenced,mmap 0x000000000828 1068 4 ___U_l_____M________________ uptodate,lru,mmap 0x00000000082c 326 1 __RU_l_____M________________ referenced,uptodate,lru,mmap 0x000000000868 335 1 ___U_lA____M________________ uptodate,lru,active,mmap 0x00000000086c 599 2 __RU_lA____M________________ referenced,uptodate,lru,active,mmap 0x000000004878 2 0 ___UDlA____M__b_____________ uptodate,dirty,lru,active,mmap,swapbacked 0x000000000a28 44 0 ___U_l___I_M________________ uptodate,lru,reclaim,mmap 0x000000000a2c 12 0 __RU_l___I_M________________ referenced,uptodate,lru,reclaim,mmap 0x000000000a68 8 0 ___U_lA__I_M________________ uptodate,lru,active,reclaim,mmap 0x000000000a6c 31 0 __RU_lA__I_M________________ referenced,uptodate,lru,active,reclaim,mmap 0x000000001000 442 1 ____________a_______________ anonymous 0x000000005808 7 0 ___U_______Ma_b_____________ uptodate,mmap,anonymous,swapbacked 0x000000005868 3371 13 ___U_lA____Ma_b_____________ uptodate,lru,active,mmap,anonymous,swapbacked 0x00000000586c 28 0 __RU_lA____Ma_b_____________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked total 513968 2007 Thanks to KOSAKI and Andi for their valuable recommendations! Cc: KOSAKI Motohiro Cc: Andi Kleen Cc: Matt Mackall Cc: Alexey Dobriyan Signed-off-by: Wu Fengguang --- fs/proc/page.c | 197 +++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 167 insertions(+), 30 deletions(-) --- mm.orig/fs/proc/page.c +++ mm/fs/proc/page.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include "internal.h" @@ -70,19 +71,172 @@ static const struct file_operations proc /* These macros are used to decouple internal flags from exported ones */ -#define KPF_LOCKED 0 -#define KPF_ERROR 1 -#define KPF_REFERENCED 2 -#define KPF_UPTODATE 3 -#define KPF_DIRTY 4 -#define KPF_LRU 5 -#define KPF_ACTIVE 6 -#define KPF_SLAB 7 -#define KPF_WRITEBACK 8 -#define KPF_RECLAIM 9 -#define KPF_BUDDY 10 +#define KPF_LOCKED 0 +#define KPF_ERROR 1 +#define KPF_REFERENCED 2 +#define KPF_UPTODATE 3 +#define KPF_DIRTY 4 +#define KPF_LRU 5 +#define KPF_ACTIVE 6 +#define KPF_SLAB 7 +#define KPF_WRITEBACK 8 +#define KPF_RECLAIM 9 +#define KPF_BUDDY 10 + +/* new additions in 2.6.31 */ +#define KPF_MMAP 11 +#define KPF_ANON 12 +#define KPF_SWAPCACHE 13 +#define KPF_SWAPBACKED 14 +#define KPF_COMPOUND_HEAD 15 +#define KPF_COMPOUND_TAIL 16 +#define KPF_UNEVICTABLE 17 +#define KPF_HWPOISON 18 +#define KPF_NOPAGE 19 + +/* kernel hacking assistances */ +#define KPF_RESERVED 32 +#define KPF_MLOCKED 33 +#define KPF_MAPPEDTODISK 34 +#define KPF_PRIVATE 35 +#define KPF_PRIVATE2 36 +#define KPF_OWNER_PRIVATE 37 +#define KPF_ARCH 38 +#define KPF_UNCACHED 39 + +/* + * Kernel flags are exported faithfully to Linus and his fellow hackers. + * Otherwise some details are masked to avoid confusing the end user: + * - some kernel flags are completely invisible + * - some kernel flags are conditionally invisible on their odd usages + */ +#ifdef CONFIG_DEBUG_KERNEL +static inline int genuine_linus(void) { return 1; } +#else +static inline int genuine_linus(void) { return 0; } +#endif + +#define kpf_copy_bit(uflags, kflags, visible, ubit, kbit) \ + do { \ + if (visible || genuine_linus()) \ + uflags |= ((kflags >> kbit) & 1) << ubit; \ + } while (0); + +/* a helper function _not_ intended for more general uses */ +static inline int page_cap_writeback_dirty(struct page *page) +{ + struct address_space *mapping; + + if (!PageSlab(page)) + mapping = page_mapping(page); + else + mapping = NULL; + + return mapping && mapping_cap_writeback_dirty(mapping); +} + +static u64 get_uflags(struct page *page) +{ + u64 k; + u64 u; + int io; + int lru; + int slab; + + /* + * pseudo flag: KPF_NOPAGE + * it differentiates a memory hole from a page with no flags + */ + if (!page) + return 1 << KPF_NOPAGE; + + k = page->flags; + u = 0; + + io = page_cap_writeback_dirty(page); + lru = k & (1 << PG_lru); + slab = k & (1 << PG_slab); + + /* + * pseudo flags for the well known (anonymous) memory mapped pages + */ + if (lru || genuine_linus()) { + if (!slab && page_mapped(page)) + u |= 1 << KPF_MMAP; + if (PageAnon(page)) + u |= 1 << KPF_ANON; + } -#define kpf_copy_bit(flags, dstpos, srcpos) (((flags >> srcpos) & 1) << dstpos) + /* + * compound pages: export both head/tail info + * they together define a compound page's start/end pos and order + */ + if (PageHuge(page) || genuine_linus()) { + if (PageHead(page)) + u |= 1 << KPF_COMPOUND_HEAD; + if (PageTail(page)) + u |= 1 << KPF_COMPOUND_TAIL; + } + + kpf_copy_bit(u, k, 1, KPF_LOCKED, PG_locked); + + /* + * Caveats on high order pages: + * PG_buddy will only be set on the head page; SLUB/SLQB do the same + * for PG_slab; SLOB won't set PG_slab at all on compound pages. + */ + kpf_copy_bit(u, k, 1, KPF_SLAB, PG_slab); + kpf_copy_bit(u, k, 1, KPF_BUDDY, PG_buddy); + + kpf_copy_bit(u, k, io, KPF_ERROR, PG_error); + kpf_copy_bit(u, k, io, KPF_DIRTY, PG_dirty); + kpf_copy_bit(u, k, io, KPF_UPTODATE, PG_uptodate); + kpf_copy_bit(u, k, io, KPF_WRITEBACK, PG_writeback); + + kpf_copy_bit(u, k, 1, KPF_LRU, PG_lru); + kpf_copy_bit(u, k, lru, KPF_REFERENCED, PG_referenced); + kpf_copy_bit(u, k, lru, KPF_ACTIVE, PG_active); + kpf_copy_bit(u, k, lru, KPF_RECLAIM, PG_reclaim); + + kpf_copy_bit(u, k, lru, KPF_SWAPCACHE, PG_swapcache); + kpf_copy_bit(u, k, lru, KPF_SWAPBACKED, PG_swapbacked); + +#ifdef CONFIG_MEMORY_FAILURE + kpf_copy_bit(u, k, 1, KPF_HWPOISON, PG_hwpoison); +#endif + +#ifdef CONFIG_UNEVICTABLE_LRU + kpf_copy_bit(u, k, lru, KPF_UNEVICTABLE, PG_unevictable); + kpf_copy_bit(u, k, 0, KPF_MLOCKED, PG_mlocked); +#endif + + kpf_copy_bit(u, k, 0, KPF_RESERVED, PG_reserved); + kpf_copy_bit(u, k, 0, KPF_MAPPEDTODISK, PG_mappedtodisk); + kpf_copy_bit(u, k, 0, KPF_PRIVATE, PG_private); + kpf_copy_bit(u, k, 0, KPF_PRIVATE2, PG_private_2); + kpf_copy_bit(u, k, 0, KPF_OWNER_PRIVATE, PG_owner_priv_1); + kpf_copy_bit(u, k, 0, KPF_ARCH, PG_arch_1); + +#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR + kpf_copy_bit(u, k, 0, KPF_UNCACHED, PG_uncached); +#endif + + if (!genuine_linus()) { + /* + * SLUB overloads some page flags which may confuse end user. + */ + if (slab) + u &= ~((1 << KPF_ACTIVE) | (1 << KPF_ERROR)); + /* + * PG_reclaim could be overloaded as PG_readahead, + * and we only want to export the first one. + */ + if (!(u & (1 << KPF_WRITEBACK))) + u &= ~(1 << KPF_RECLAIM); + } + + return u; +}; static ssize_t kpageflags_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) @@ -92,7 +246,6 @@ static ssize_t kpageflags_read(struct fi unsigned long src = *ppos; unsigned long pfn; ssize_t ret = 0; - u64 kflags, uflags; pfn = src / KPMSIZE; count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src); @@ -104,24 +257,8 @@ static ssize_t kpageflags_read(struct fi ppage = pfn_to_page(pfn); else ppage = NULL; - if (!ppage) - kflags = 0; - else - kflags = ppage->flags; - - uflags = kpf_copy_bit(kflags, KPF_LOCKED, PG_locked) | - kpf_copy_bit(kflags, KPF_ERROR, PG_error) | - kpf_copy_bit(kflags, KPF_REFERENCED, PG_referenced) | - kpf_copy_bit(kflags, KPF_UPTODATE, PG_uptodate) | - kpf_copy_bit(kflags, KPF_DIRTY, PG_dirty) | - kpf_copy_bit(kflags, KPF_LRU, PG_lru) | - kpf_copy_bit(kflags, KPF_ACTIVE, PG_active) | - kpf_copy_bit(kflags, KPF_SLAB, PG_slab) | - kpf_copy_bit(kflags, KPF_WRITEBACK, PG_writeback) | - kpf_copy_bit(kflags, KPF_RECLAIM, PG_reclaim) | - kpf_copy_bit(kflags, KPF_BUDDY, PG_buddy); - if (put_user(uflags, out)) { + if (put_user(get_uflags(ppage), out)) { ret = -EFAULT; break; } -- -- 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/