1. 09 Oct, 2012 40 commits
    • Heiko Carstens's avatar
      s390/mm: let kernel text section always begin at 1MB · 9be5f34f
      Heiko Carstens authored
      Let the kernel text section always begin at 1MB. This allows to always have
      a large frame in the identity mapping of the kernel image for beginning of
      the text section, if the machine has EDAT1 support.
      Moving the beginning from 64K to 1MB doesn't cost any memory, since we make
      the memory between 64K and 1MB available for the page allocator.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      9be5f34f
    • Heiko Carstens's avatar
      s390/mm: fix mapping of read-only kernel text section · 8fe234d3
      Heiko Carstens authored
      Within the identity mapping the kernel text section is mapped read-only.
      However when mapping the first and last page of the text section we must
      round upwards and downwards respectively, if only parts of a page belong
      to the section.
      Otherwise potential rw data can be mapped read-only. So the rounding must
      be done just the other way we have it right now.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      8fe234d3
    • Heiko Carstens's avatar
      s390/mm: add page table dumper · e76e82d7
      Heiko Carstens authored
      This is more or less the same as the x86 page table dumper which was
      merged four years ago: 926e5392 "x86: add code to dump the (kernel)
      page tables for visual inspection by kernel developers".
      
      We add a file at /sys/kernel/debug/kernel_page_tables for debugging
      purposes so it's quite easy to see the kernel page table layout and
      possible odd mappings:
      
      ---[ Identity Mapping ]---
      0x0000000000000000-0x0000000000100000        1M PTE RW
      ---[ Kernel Image Start ]---
      0x0000000000100000-0x0000000000800000        7M PMD RO
      0x0000000000800000-0x00000000008a9000      676K PTE RO
      0x00000000008a9000-0x0000000000900000      348K PTE RW
      0x0000000000900000-0x0000000001500000       12M PMD RW
      ---[ Kernel Image End ]---
      0x0000000001500000-0x0000000280000000    10219M PMD RW
      0x0000000280000000-0x000003d280000000     3904G PUD I
      ---[ vmemmap Area ]---
      0x000003d280000000-0x000003d288c00000      140M PTE RW
      0x000003d288c00000-0x000003d300000000     1908M PMD I
      0x000003d300000000-0x000003e000000000       52G PUD I
      ---[ vmalloc Area ]---
      0x000003e000000000-0x000003e000009000       36K PTE RW
      0x000003e000009000-0x000003e0000ee000      916K PTE I
      0x000003e0000ee000-0x000003e000146000      352K PTE RW
      0x000003e000146000-0x000003e000200000      744K PTE I
      0x000003e000200000-0x000003e080000000     2046M PMD I
      0x000003e080000000-0x0000040000000000      126G PUD I
      
      This usually makes only sense for kernel developers. The output
      with CONFIG_DEBUG_PAGEALLOC is not very helpful, because of the
      huge number of mapped out pages, however I decided for the time
      being to not add a !DEBUG_PAGEALLOC dependency.
      Maybe it's helpful for somebody even with that option.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      e76e82d7
    • Martin Schwidefsky's avatar
      s390: add support to start the kernel in 64 bit mode. · 51eee033
      Martin Schwidefsky authored
      Do the switch to z/Architecture (alias 64 bit) mode early in head.S.
      If the machine is already running in 64 bit mode the sigp turns into
      a nop. With this change it doesn't matter in which mode the kernel
      is started.
      Reviewd-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      51eee033
    • Heiko Carstens's avatar
      s390/mm,pageattr: remove superfluous EXPORT_SYMBOLs · cc5b9a45
      Heiko Carstens authored
      Remove some EXPORT_SYMBOLs. There is no module code anywhere
      which calls these pageattr functions.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      cc5b9a45
    • Heiko Carstens's avatar
      s390/mm,pageattr: add more page table walk sanity checks · 5b1ba9e3
      Heiko Carstens authored
      The current page table walk code in pageattr.c only checks for large pages
      while walking the kernel page table, but happily assumes that everything
      else is just fine.
      Add more checks so we never access invalid memory regions.
      Reviewed-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      5b1ba9e3
    • Heiko Carstens's avatar
      s390/mm: fix pmd_huge() usage for kernel mapping · 378b1e7a
      Heiko Carstens authored
      pmd_huge() will always return 0 on !HUGETLBFS, however we use that helper
      function when walking the kernel page tables to decide if we have a
      1MB page frame or not.
      Since we create 1MB frames for the kernel 1:1 mapping independently of
      HUGETLBFS this can lead to incorrect storage accesses since the code
      can assume that we have a pointer to a page table instead of a pointer
      to a 1MB frame.
      
      Fix this by adding a pmd_large() primitive like other architectures have
      it already and remove all references to HUGETLBFS/HUGETLBPAGE from the
      code that walks kernel page tables.
      Reviewed-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      378b1e7a
    • Sebastian Ott's avatar
      s390/dcssblk: cleanup device attribute usage · 521b3d79
      Sebastian Ott authored
      Let the driver core handle device attribute creation and removal. This
      will simplify the code and eliminates races between attribute
      availability and userspace notification via uevents.
      Signed-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      521b3d79
    • Heiko Carstens's avatar
      s390/mm: use pfmf instruction to initialize storage keys · 85e9d0e5
      Heiko Carstens authored
      Make use of the pfmf instruction, if available, to initialize storage keys
      of whole 1MB or 2GB frames instead of initializing every single page with
      the sske instruction.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      85e9d0e5
    • Heiko Carstens's avatar
      s390/facilities: cleanup PFMF and HPAGE machine facility detection · 3c7ef08b
      Heiko Carstens authored
      MACHINE_HAS_PFMF and MACHINE_HAS_HPAGE actually have the same semantics:
      the cpu has the EDAT1 facility installed in zArch mode. So remove one
      of the feature flags in machine_flags and rename the other one to EDAT1.
      
      The two old macros simply get mapped to MACHINE_HAS_EDAT1.
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      3c7ef08b
    • Linus Torvalds's avatar
      Merge branch 'akpm' (Andrew's patch-bomb) · 9e2d8656
      Linus Torvalds authored
      Merge patches from Andrew Morton:
       "A few misc things and very nearly all of the MM tree.  A tremendous
        amount of stuff (again), including a significant rbtree library
        rework."
      
      * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (160 commits)
        sparc64: Support transparent huge pages.
        mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd().
        mm: Add and use update_mmu_cache_pmd() in transparent huge page code.
        sparc64: Document PGD and PMD layout.
        sparc64: Eliminate PTE table memory wastage.
        sparc64: Halve the size of PTE tables
        sparc64: Only support 4MB huge pages and 8KB base pages.
        memory-hotplug: suppress "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning
        mm: memcg: clean up mm_match_cgroup() signature
        mm: document PageHuge somewhat
        mm: use %pK for /proc/vmallocinfo
        mm, thp: fix mlock statistics
        mm, thp: fix mapped pages avoiding unevictable list on mlock
        memory-hotplug: update memory block's state and notify userspace
        memory-hotplug: preparation to notify memory block's state at memory hot remove
        mm: avoid section mismatch warning for memblock_type_name
        make GFP_NOTRACK definition unconditional
        cma: decrease cc.nr_migratepages after reclaiming pagelist
        CMA: migrate mlocked pages
        kpageflags: fix wrong KPF_THP on non-huge compound pages
        ...
      9e2d8656
    • David Miller's avatar
      sparc64: Support transparent huge pages. · 9e695d2e
      David Miller authored
      This is relatively easy since PMD's now cover exactly 4MB of memory.
      
      Our PMD entries are 32-bits each, so we use a special encoding.  The
      lowest bit, PMD_ISHUGE, determines the interpretation.  This is possible
      because sparc64's page tables are purely software entities so we can use
      whatever encoding scheme we want.  We just have to make the TLB miss
      assembler page table walkers aware of the layout.
      
      set_pmd_at() works much like set_pte_at() but it has to operate in two
      page from a table of non-huge PTEs, so we have to queue up TLB flushes
      based upon what mappings are valid in the PTE table.  In the second regime
      we are going from huge-page to non-huge-page, and in that case we need
      only queue up a single TLB flush to push out the huge page mapping.
      
      We still have 5 bits remaining in the huge PMD encoding so we can very
      likely support any new pieces of THP state tracking that might get added
      in the future.
      
      With lots of help from Johannes Weiner.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9e695d2e
    • David Miller's avatar
      mm: thp: Use more portable PMD clearing sequenece in zap_huge_pmd(). · f5c8ad47
      David Miller authored
      Invalidation sequences are handled in various ways on various
      architectures.
      
      One way, which sparc64 uses, is to let the set_*_at() functions accumulate
      pending flushes into a per-cpu array.  Then the flush_tlb_range() et al.
      calls process the pending TLB flushes.
      
      In this regime, the __tlb_remove_*tlb_entry() implementations are
      essentially NOPs.
      
      The canonical PTE zap in mm/memory.c is:
      
      			ptent = ptep_get_and_clear_full(mm, addr, pte,
      							tlb->fullmm);
      			tlb_remove_tlb_entry(tlb, pte, addr);
      
      With a subsequent tlb_flush_mmu() if needed.
      
      Mirror this in the THP PMD zapping using:
      
      		orig_pmd = pmdp_get_and_clear(tlb->mm, addr, pmd);
      		page = pmd_page(orig_pmd);
      		tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
      
      And we properly accomodate TLB flush mechanims like the one described
      above.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f5c8ad47
    • David Miller's avatar
      mm: Add and use update_mmu_cache_pmd() in transparent huge page code. · b113da65
      David Miller authored
      The transparent huge page code passes a PMD pointer in as the third
      argument of update_mmu_cache(), which expects a PTE pointer.
      
      This never got noticed because X86 implements update_mmu_cache() as a
      macro and thus we don't get any type checking, and X86 is the only
      architecture which supports transparent huge pages currently.
      
      Before other architectures can support transparent huge pages properly we
      need to add a new interface which will take a PMD pointer as the third
      argument rather than a PTE pointer.
      
      [akpm@linux-foundation.org: implement update_mm_cache_pmd() for s390]
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b113da65
    • David Miller's avatar
      sparc64: Document PGD and PMD layout. · dbc9fdf0
      David Miller authored
      We're going to be messing around with the PMD interpretation and layout
      for the sake of transparent huge pages, so we better clearly document what
      we're starting with.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      dbc9fdf0
    • David Miller's avatar
      sparc64: Eliminate PTE table memory wastage. · c460bec7
      David Miller authored
      We've split up the PTE tables so that they take up half a page instead of
      a full page.  This is in order to facilitate transparent huge page
      support, which works much better if our PMDs cover 4MB instead of 8MB.
      
      What we do is have a one-behind cache for PTE table allocations in the
      mm struct.
      
      This logic triggers only on allocations.  For example, we don't try to
      keep track of free'd up page table blocks in the style that the s390 port
      does.
      
      There were only two slightly annoying aspects to this change:
      
      1) Changing pgtable_t to be a "pte_t *".  There's all of this special
         logic in the TLB free paths that needed adjustments, as did the
         PMD populate interfaces.
      
      2) init_new_context() needs to zap the pointer, since the mm struct
         just gets copied from the parent on fork.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c460bec7
    • David Miller's avatar
      sparc64: Halve the size of PTE tables · 56a70b8c
      David Miller authored
      The reason we want to do this is to facilitate transparent huge page
      support.
      
      Right now PMD's cover 8MB of address space, and our huge page size is 4MB.
       The current transparent hugepage support is not able to handle HPAGE_SIZE
      != PMD_SIZE.
      
      So make PTE tables be sized to half of a page instead of a full page.
      
      We can still map properly the whole supported virtual address range which
      on sparc64 requires 44 bits.  Add a compile time CPP test which ensures
      that this requirement is always met.
      
      There is a minor inefficiency added by this change.  We only use half of
      the page for PTE tables.  It's not trivial to use only half of the page
      yet still get all of the pgtable_page_{ctor,dtor}() stuff working
      properly.  It is doable, and that will come in a subsequent change.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      56a70b8c
    • David Miller's avatar
      sparc64: Only support 4MB huge pages and 8KB base pages. · 15b9350a
      David Miller authored
      Narrowing the scope of the page size configurations will make the
      transparent hugepage changes much simpler.
      
      In the end what we really want to do is have the kernel support multiple
      huge page sizes and use whatever is appropriate as the context dictactes.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      15b9350a
    • Yasuaki Ishimatsu's avatar
      memory-hotplug: suppress "Trying to free nonexistent resource... · d760afd4
      Yasuaki Ishimatsu authored
      memory-hotplug: suppress "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning
      
      When our x86 box calls __remove_pages(), release_mem_region() shows many
      warnings.  And x86 box cannot unregister iomem_resource.
      
        "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>"
      
      release_mem_region() has been changed to be called in each
      PAGES_PER_SECTION by commit de7f0cba ("memory hotplug: release
      memory regions in PAGES_PER_SECTION chunks").  Because powerpc registers
      iomem_resource in each PAGES_PER_SECTION chunk.  But when I hot add
      memory on x86 box, iomem_resource is register in each _CRS not
      PAGES_PER_SECTION chunk.  So x86 box unregisters iomem_resource.
      
      The patch fixes the problem.
      Signed-off-by: default avatarYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Jiang Liu <liuj97@gmail.com>
      Cc: Len Brown <len.brown@intel.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Wen Congyang <wency@cn.fujitsu.com>
      Cc: Dave Hansen <dave@linux.vnet.ibm.com>
      Cc: Nathan Fontenot <nfont@austin.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d760afd4
    • Johannes Weiner's avatar
      mm: memcg: clean up mm_match_cgroup() signature · 587af308
      Johannes Weiner authored
      It really should return a boolean for match/no match.  And since it takes
      a memcg, not a cgroup, fix that parameter name as well.
      
      [akpm@linux-foundation.org: mm_match_cgroup() is not a macro]
      Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      587af308
    • Andrew Morton's avatar
      mm: document PageHuge somewhat · 7795912c
      Andrew Morton authored
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7795912c
    • Kees Cook's avatar
      mm: use %pK for /proc/vmallocinfo · 45ec1690
      Kees Cook authored
      In the paranoid case of sysctl kernel.kptr_restrict=2, mask the kernel
      virtual addresses in /proc/vmallocinfo too.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Reported-by: default avatarBrad Spengler <spender@grsecurity.net>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      45ec1690
    • David Rientjes's avatar
      mm, thp: fix mlock statistics · 8449d21f
      David Rientjes authored
      NR_MLOCK is only accounted in single page units: there's no logic to
      handle transparent hugepages.  This patch checks the appropriate number of
      pages to adjust the statistics by so that the correct amount of memory is
      reflected.
      
      Currently:
      
      		$ grep Mlocked /proc/meminfo
      		Mlocked:           19636 kB
      
      	#define MAP_SIZE	(4 << 30)	/* 4GB */
      
      	void *ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
      			 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
      	mlock(ptr, MAP_SIZE);
      
      		$ grep Mlocked /proc/meminfo
      		Mlocked:           29844 kB
      
      	munlock(ptr, MAP_SIZE);
      
      		$ grep Mlocked /proc/meminfo
      		Mlocked:           19636 kB
      
      And with this patch:
      
      		$ grep Mlock /proc/meminfo
      		Mlocked:           19636 kB
      
      	mlock(ptr, MAP_SIZE);
      
      		$ grep Mlock /proc/meminfo
      		Mlocked:         4213664 kB
      
      	munlock(ptr, MAP_SIZE);
      
      		$ grep Mlock /proc/meminfo
      		Mlocked:           19636 kB
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Reported-by: default avatarHugh Dickens <hughd@google.com>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Reviewed-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Reviewed-by: default avatarMichel Lespinasse <walken@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8449d21f
    • David Rientjes's avatar
      mm, thp: fix mapped pages avoiding unevictable list on mlock · b676b293
      David Rientjes authored
      When a transparent hugepage is mapped and it is included in an mlock()
      range, follow_page() incorrectly avoids setting the page's mlock bit and
      moving it to the unevictable lru.
      
      This is evident if you try to mlock(), munlock(), and then mlock() a
      range again.  Currently:
      
      	#define MAP_SIZE	(4 << 30)	/* 4GB */
      
      	void *ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
      			 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
      	mlock(ptr, MAP_SIZE);
      
      		$ grep -E "Unevictable|Inactive\(anon" /proc/meminfo
      		Inactive(anon):     6304 kB
      		Unevictable:     4213924 kB
      
      	munlock(ptr, MAP_SIZE);
      
      		Inactive(anon):  4186252 kB
      		Unevictable:       19652 kB
      
      	mlock(ptr, MAP_SIZE);
      
      		Inactive(anon):  4198556 kB
      		Unevictable:       21684 kB
      
      Notice that less than 2MB was added to the unevictable list; this is
      because these pages in the range are not transparent hugepages since the
      4GB range was allocated with mmap() and has no specific alignment.  If
      posix_memalign() were used instead, unevictable would not have grown at
      all on the second mlock().
      
      The fix is to call mlock_vma_page() so that the mlock bit is set and the
      page is added to the unevictable list.  With this patch:
      
      	mlock(ptr, MAP_SIZE);
      
      		Inactive(anon):     4056 kB
      		Unevictable:     4213940 kB
      
      	munlock(ptr, MAP_SIZE);
      
      		Inactive(anon):  4198268 kB
      		Unevictable:       19636 kB
      
      	mlock(ptr, MAP_SIZE);
      
      		Inactive(anon):     4008 kB
      		Unevictable:     4213940 kB
      Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Acked-by: default avatarHugh Dickins <hughd@google.com>
      Reviewed-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Michel Lespinasse <walken@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b676b293
    • Wen Congyang's avatar
      memory-hotplug: update memory block's state and notify userspace · e90bdb7f
      Wen Congyang authored
      remove_memory() will be called when hot removing a memory device.  But
      even if offlining memory, we cannot notice it.  So the patch updates the
      memory block's state and sends notification to userspace.
      
      Additionally, the memory device may contain more than one memory block.
      If the memory block has been offlined, __offline_pages() will fail.  So we
      should try to offline one memory block at a time.
      
      Thus remove_memory() also check each memory block's state.  So there is no
      need to check the memory block's state before calling remove_memory().
      Signed-off-by: default avatarWen Congyang <wency@cn.fujitsu.com>
      Signed-off-by: default avatarYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Jiang Liu <liuj97@gmail.com>
      Cc: Len Brown <len.brown@intel.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e90bdb7f
    • Wen Congyang's avatar
      memory-hotplug: preparation to notify memory block's state at memory hot remove · a16cee10
      Wen Congyang authored
      remove_memory() is called in two cases:
      1. echo offline >/sys/devices/system/memory/memoryXX/state
      2. hot remove a memory device
      
      In the 1st case, the memory block's state is changed and the notification
      that memory block's state changed is sent to userland after calling
      remove_memory().  So user can notice memory block is changed.
      
      But in the 2nd case, the memory block's state is not changed and the
      notification is not also sent to userspcae even if calling
      remove_memory().  So user cannot notice memory block is changed.
      
      For adding the notification at memory hot remove, the patch just prepare
      as follows:
      1st case uses offline_pages() for offlining memory.
      2nd case uses remove_memory() for offlining memory and changing memory block's
          state and notifing the information.
      
      The patch does not implement notification to remove_memory().
      Signed-off-by: default avatarWen Congyang <wency@cn.fujitsu.com>
      Signed-off-by: default avatarYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Jiang Liu <liuj97@gmail.com>
      Cc: Len Brown <len.brown@intel.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a16cee10
    • Raghavendra D Prabhu's avatar
      mm: avoid section mismatch warning for memblock_type_name · c2233116
      Raghavendra D Prabhu authored
      Following section mismatch warning is thrown during build;
      
          WARNING: vmlinux.o(.text+0x32408f): Section mismatch in reference from the function memblock_type_name() to the variable .meminit.data:memblock
          The function memblock_type_name() references
          the variable __meminitdata memblock.
          This is often because memblock_type_name lacks a __meminitdata
          annotation or the annotation of memblock is wrong.
      
      This is because memblock_type_name makes reference to memblock variable
      with attribute __meminitdata.  Hence, the warning (even if the function is
      inline).
      
      [akpm@linux-foundation.org: remove inline]
      Signed-off-by: default avatarRaghavendra D Prabhu <rprabhu@wnohang.net>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c2233116
    • Glauber Costa's avatar
      make GFP_NOTRACK definition unconditional · 3e648ebe
      Glauber Costa authored
      There was a general sentiment in a recent discussion (See
      https://lkml.org/lkml/2012/9/18/258) that the __GFP flags should be
      defined unconditionally.  Currently, the only offender is GFP_NOTRACK,
      which is conditional to KMEMCHECK.
      Signed-off-by: default avatarGlauber Costa <glommer@parallels.com>
      Acked-by: default avatarChristoph Lameter <cl@linux.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3e648ebe
    • Minchan Kim's avatar
      cma: decrease cc.nr_migratepages after reclaiming pagelist · beb51eaa
      Minchan Kim authored
      reclaim_clean_pages_from_list() reclaims clean pages before migration so
      cc.nr_migratepages should be updated.  Currently, there is no problem but
      it can be wrong if we try to use the value in future.
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Michal Nazarewicz <mina86@mina86.com>
      Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
      Cc: Marek Szyprowski <m.szyprowski@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      beb51eaa
    • Minchan Kim's avatar
      CMA: migrate mlocked pages · e46a2879
      Minchan Kim authored
      Presently CMA cannot migrate mlocked pages so it ends up failing to allocate
      contiguous memory space.
      
      This patch makes mlocked pages be migrated out.  Of course, it can affect
      realtime processes but in CMA usecase, contiguous memory allocation failing
      is far worse than access latency to an mlocked page being variable while
      CMA is running.  If someone wants to make the system realtime, he shouldn't
      enable CMA because stalls can still happen at random times.
      
      [akpm@linux-foundation.org: tweak comment text, per Mel]
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Acked-by: default avatarMel Gorman <mgorman@suse.de>
      Cc: Michal Nazarewicz <mina86@mina86.com>
      Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
      Cc: Marek Szyprowski <m.szyprowski@samsung.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e46a2879
    • Naoya Horiguchi's avatar
      kpageflags: fix wrong KPF_THP on non-huge compound pages · 7a71932d
      Naoya Horiguchi authored
      KPF_THP can be set on non-huge compound pages (like slab pages or pages
      allocated by drivers with __GFP_COMP) because PageTransCompound only
      checks PG_head and PG_tail.  Obviously this is a bug and breaks user space
      applications which look for thp via /proc/kpageflags.
      
      This patch rules out setting KPF_THP wrongly by additionally checking
      PageLRU on the head pages.
      Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Acked-by: default avatarDavid Rientjes <rientjes@google.com>
      Reviewed-by: default avatarFengguang Wu <fengguang.wu@intel.com>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7a71932d
    • Yan Hong's avatar
      fs/fs-writeback.c: remove unneccesary parameter of __writeback_single_inode() · cd8ed2a4
      Yan Hong authored
      The parameter 'wb' is never used in this function.
      Signed-off-by: default avatarYan Hong <clouds.yan@gmail.com>
      Acked-by: default avatarWu Fengguang <fengguang.wu@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      cd8ed2a4
    • Robert P. J. Day's avatar
    • Hugh Dickins's avatar
      mm: remove unevictable_pgs_mlockfreed · 8befedfe
      Hugh Dickins authored
      Simply remove UNEVICTABLE_MLOCKFREED and unevictable_pgs_mlockfreed line
      from /proc/vmstat: Johannes and Mel point out that it was very unlikely to
      have been used by any tool, and of course we can restore it easily enough
      if that turns out to be wrong.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Michel Lespinasse <walken@google.com>
      Cc: Ying Han <yinghan@google.com>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8befedfe
    • Minchan Kim's avatar
      memory-hotplug: fix zone stat mismatch · 5a883813
      Minchan Kim authored
      During memory-hotplug, I found NR_ISOLATED_[ANON|FILE] are increasing,
      causing the kernel to hang.  When the system doesn't have enough free
      pages, it enters reclaim but never reclaim any pages due to
      too_many_isolated()==true and loops forever.
      
      The cause is that when we do memory-hotadd after memory-remove,
      __zone_pcp_update() clears a zone's ZONE_STAT_ITEMS in setup_pageset()
      although the vm_stat_diff of all CPUs still have values.
      
      In addtion, when we offline all pages of the zone, we reset them in
      zone_pcp_reset without draining so we loss some zone stat item.
      Reviewed-by: default avatarWen Congyang <wency@cn.fujitsu.com>
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5a883813
    • Minchan Kim's avatar
      mm: revert 0def08e3 ("mm/mempolicy.c: check return code of check_range") · 08270807
      Minchan Kim authored
      Revert commit 0def08e3 because check_range can't fail in
      migrate_to_node with considering current usecases.
      
      Quote from Johannes
      
      : I think it makes sense to revert.  Not because of the semantics, but I
      : just don't see how check_range() could even fail for this callsite:
      :
      : 1. we pass mm->mmap->vm_start in there, so we should not fail due to
      :    find_vma()
      :
      : 2. we pass MPOL_MF_DISCONTIG_OK, so the discontig checks do not apply
      :    and so can not fail
      :
      : 3. we pass MPOL_MF_MOVE | MPOL_MF_MOVE_ALL, the page table loops will
      :    continue until addr == end, so we never fail with -EIO
      
      And I added a new VM_BUG_ON for checking migrate_to_node's future usecase
      which might pass to MPOL_MF_STRICT.
      Suggested-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
      Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Vasiliy Kulikov <segooon@gmail.com>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      08270807
    • Haggai Eran's avatar
      mm: wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end · 6bdb913f
      Haggai Eran authored
      In order to allow sleeping during invalidate_page mmu notifier calls, we
      need to avoid calling when holding the PT lock.  In addition to its direct
      calls, invalidate_page can also be called as a substitute for a change_pte
      call, in case the notifier client hasn't implemented change_pte.
      
      This patch drops the invalidate_page call from change_pte, and instead
      wraps all calls to change_pte with invalidate_range_start and
      invalidate_range_end calls.
      
      Note that change_pte still cannot sleep after this patch, and that clients
      implementing change_pte should not take action on it in case the number of
      outstanding invalidate_range_start calls is larger than one, otherwise
      they might miss a later invalidation.
      Signed-off-by: default avatarHaggai Eran <haggaie@mellanox.com>
      Cc: Andrea Arcangeli <andrea@qumranet.com>
      Cc: Sagi Grimberg <sagig@mellanox.com>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
      Cc: Or Gerlitz <ogerlitz@mellanox.com>
      Cc: Haggai Eran <haggaie@mellanox.com>
      Cc: Shachar Raindel <raindel@mellanox.com>
      Cc: Liran Liss <liranl@mellanox.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Avi Kivity <avi@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6bdb913f
    • Sagi Grimberg's avatar
      mm: move all mmu notifier invocations to be done outside the PT lock · 2ec74c3e
      Sagi Grimberg authored
      In order to allow sleeping during mmu notifier calls, we need to avoid
      invoking them under the page table spinlock.  This patch solves the
      problem by calling invalidate_page notification after releasing the lock
      (but before freeing the page itself), or by wrapping the page invalidation
      with calls to invalidate_range_begin and invalidate_range_end.
      
      To prevent accidental changes to the invalidate_range_end arguments after
      the call to invalidate_range_begin, the patch introduces a convention of
      saving the arguments in consistently named locals:
      
      	unsigned long mmun_start;	/* For mmu_notifiers */
      	unsigned long mmun_end;	/* For mmu_notifiers */
      
      	...
      
      	mmun_start = ...
      	mmun_end = ...
      	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
      
      	...
      
      	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
      
      The patch changes code to use this convention for all calls to
      mmu_notifier_invalidate_range_start/end, except those where the calls are
      close enough so that anyone who glances at the code can see the values
      aren't changing.
      
      This patchset is a preliminary step towards on-demand paging design to be
      added to the RDMA stack.
      
      Why do we want on-demand paging for Infiniband?
      
        Applications register memory with an RDMA adapter using system calls,
        and subsequently post IO operations that refer to the corresponding
        virtual addresses directly to HW.  Until now, this was achieved by
        pinning the memory during the registration calls.  The goal of on demand
        paging is to avoid pinning the pages of registered memory regions (MRs).
         This will allow users the same flexibility they get when swapping any
        other part of their processes address spaces.  Instead of requiring the
        entire MR to fit in physical memory, we can allow the MR to be larger,
        and only fit the current working set in physical memory.
      
      Why should anyone care?  What problems are users currently experiencing?
      
        This can make programming with RDMA much simpler.  Today, developers
        that are working with more data than their RAM can hold need either to
        deregister and reregister memory regions throughout their process's
        life, or keep a single memory region and copy the data to it.  On demand
        paging will allow these developers to register a single MR at the
        beginning of their process's life, and let the operating system manage
        which pages needs to be fetched at a given time.  In the future, we
        might be able to provide a single memory access key for each process
        that would provide the entire process's address as one large memory
        region, and the developers wouldn't need to register memory regions at
        all.
      
      Is there any prospect that any other subsystems will utilise these
      infrastructural changes?  If so, which and how, etc?
      
        As for other subsystems, I understand that XPMEM wanted to sleep in
        MMU notifiers, as Christoph Lameter wrote at
        http://lkml.indiana.edu/hypermail/linux/kernel/0802.1/0460.html and
        perhaps Andrea knows about other use cases.
      
        Scheduling in mmu notifications is required since we need to sync the
        hardware with the secondary page tables change.  A TLB flush of an IO
        device is inherently slower than a CPU TLB flush, so our design works by
        sending the invalidation request to the device, and waiting for an
        interrupt before exiting the mmu notifier handler.
      
      Avi said:
      
        kvm may be a buyer.  kvm::mmu_lock, which serializes guest page
        faults, also protects long operations such as destroying large ranges.
        It would be good to convert it into a spinlock, but as it is used inside
        mmu notifiers, this cannot be done.
      
        (there are alternatives, such as keeping the spinlock and using a
        generation counter to do the teardown in O(1), which is what the "may"
        is doing up there).
      
      [akpm@linux-foundation.orgpossible speed tweak in hugetlb_cow(), cleanups]
      Signed-off-by: default avatarAndrea Arcangeli <andrea@qumranet.com>
      Signed-off-by: default avatarSagi Grimberg <sagig@mellanox.com>
      Signed-off-by: default avatarHaggai Eran <haggaie@mellanox.com>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
      Cc: Or Gerlitz <ogerlitz@mellanox.com>
      Cc: Haggai Eran <haggaie@mellanox.com>
      Cc: Shachar Raindel <raindel@mellanox.com>
      Cc: Liran Liss <liranl@mellanox.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Cc: Avi Kivity <avi@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2ec74c3e
    • Michal Hocko's avatar
      hugetlb: do not use vma_hugecache_offset() for vma_prio_tree_foreach · 36e4f20a
      Michal Hocko authored
      Commit 0c176d52 ("mm: hugetlb: fix pgoff computation when unmapping
      page from vma") fixed pgoff calculation but it has replaced it by
      vma_hugecache_offset() which is not approapriate for offsets used for
      vma_prio_tree_foreach() because that one expects index in page units
      rather than in huge_page_shift.
      
      Johannes said:
      
      : The resulting index may not be too big, but it can be too small: assume
      : hpage size of 2M and the address to unmap to be 0x200000.  This is regular
      : page index 512 and hpage index 1.  If you have a VMA that maps the file
      : only starting at the second huge page, that VMAs vm_pgoff will be 512 but
      : you ask for offset 1 and miss it even though it does map the page of
      : interest.  hugetlb_cow() will try to unmap, miss the vma, and retry the
      : cow until the allocation succeeds or the skipped vma(s) go away.
      Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarHillf Danton <dhillf@gmail.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: David Rientjes <rientjes@google.com>
      Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      36e4f20a
    • Andrea Arcangeli's avatar
      mm: thp: fix pmd_present for split_huge_page and PROT_NONE with THP · 027ef6c8
      Andrea Arcangeli authored
      In many places !pmd_present has been converted to pmd_none.  For pmds
      that's equivalent and pmd_none is quicker so using pmd_none is better.
      
      However (unless we delete pmd_present) we should provide an accurate
      pmd_present too.  This will avoid the risk of code thinking the pmd is non
      present because it's under __split_huge_page_map, see the pmd_mknotpresent
      there and the comment above it.
      
      If the page has been mprotected as PROT_NONE, it would also lead to a
      pmd_present false negative in the same way as the race with
      split_huge_page.
      
      Because the PSE bit stays on at all times (both during split_huge_page and
      when the _PAGE_PROTNONE bit get set), we could only check for the PSE bit,
      but checking the PROTNONE bit too is still good to remember pmd_present
      must always keep PROT_NONE into account.
      
      This explains a not reproducible BUG_ON that was seldom reported on the
      lists.
      
      The same issue is in pmd_large, it would go wrong with both PROT_NONE and
      if it races with split_huge_page.
      Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Acked-by: default avatarRik van Riel <riel@redhat.com>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      027ef6c8