lkml.org 
[lkml]   [2007]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [patch 4/6] mm: merge populate and nopage into fault (fixes nonlinear)
    On Wed, Mar 07, 2007 at 09:27:55AM +0100, Ingo Molnar wrote:
    >
    > * Nick Piggin <npiggin@suse.de> wrote:
    >
    > > Then 4,5,6 is the fault/nonlinear rewrite, take it or leave it. I
    > > thought you would have liked the patches...
    >
    > btw., if we decide that nonlinear isnt worth the continuing maintainance
    > pain, we could internally implement/emulate sys_remap_file_pages() via a
    > call to mremap() and essentially deprecate it, without breaking the ABI
    > - and remove all the nonlinear code. (This would split fremap areas into
    > separate vmas)

    Well I think it has a few possible uses outside the PAE database
    workloads. UML for one seem to be interested... as much as I don't
    use them, I think nonlinear mappings are kinda cool ;)

    After these patches, I don't think there is too much burden. The main
    thing left really is just the objrmap stuff, but that is just handled
    with a minimal 'dumb' algorithm that doesn't cost much.

    Then the core of it is just the file pte handling, which really doesn't
    seem to be much problem.

    Apart from a handful of trivial if (pte_file()) cases throughout mm/,
    our maintainance burden basically now amounts to the following patch.
    Even the rmap.c change looks bigger than it is because I split out
    the nonlinear unmapping code from try_to_unmap_file. Not too bad, eh? :)

    --

    include/asm-powerpc/pgtable.h | 12 ++++
    mm/Kconfig | 6 ++
    mm/Makefile | 6 +-
    mm/rmap.c | 101 +++++++++++++++++++++++++-----------------
    4 files changed, 83 insertions(+), 42 deletions(-)

    Index: linux-2.6/include/asm-powerpc/pgtable.h
    ===================================================================
    --- linux-2.6.orig/include/asm-powerpc/pgtable.h
    +++ linux-2.6/include/asm-powerpc/pgtable.h
    @@ -243,7 +243,12 @@ static inline int pte_write(pte_t pte) {
    static inline int pte_exec(pte_t pte) { return pte_val(pte) & _PAGE_EXEC;}
    static inline int pte_dirty(pte_t pte) { return pte_val(pte) & _PAGE_DIRTY;}
    static inline int pte_young(pte_t pte) { return pte_val(pte) & _PAGE_ACCESSED;}
    +
    +#ifdef CONFIG_NONLINEAR
    static inline int pte_file(pte_t pte) { return pte_val(pte) & _PAGE_FILE;}
    +#else
    +static inline int pte_file(pte_t pte) { return 0; }
    +#endif

    static inline void pte_uncache(pte_t pte) { pte_val(pte) |= _PAGE_NO_CACHE; }
    static inline void pte_cache(pte_t pte) { pte_val(pte) &= ~_PAGE_NO_CACHE; }
    @@ -483,9 +488,16 @@ extern void update_mmu_cache(struct vm_a
    #define __swp_entry(type, offset) ((swp_entry_t){((type)<< 1)|((offset)<<8)})
    #define __pte_to_swp_entry(pte) ((swp_entry_t){pte_val(pte) >> PTE_RPN_SHIFT})
    #define __swp_entry_to_pte(x) ((pte_t) { (x).val << PTE_RPN_SHIFT })
    +
    +#ifdef CONFIG_NONLINEAR
    #define pte_to_pgoff(pte) (pte_val(pte) >> PTE_RPN_SHIFT)
    #define pgoff_to_pte(off) ((pte_t) {((off) << PTE_RPN_SHIFT)|_PAGE_FILE})
    #define PTE_FILE_MAX_BITS (BITS_PER_LONG - PTE_RPN_SHIFT)
    +#else
    +#define pte_to_pgoff(pte) ({BUG(); -1;})
    +#define pgoff_to_pte(off) ({BUG(); (pte_t){-1};})
    +#define PTE_FILE_MAX_BITS 0
    +#endif

    /*
    * kern_addr_valid is intended to indicate whether an address is a valid
    Index: linux-2.6/mm/Kconfig
    ===================================================================
    --- linux-2.6.orig/mm/Kconfig
    +++ linux-2.6/mm/Kconfig
    @@ -142,6 +142,12 @@ config SPLIT_PTLOCK_CPUS
    #
    # support for page migration
    #
    +config NONLINEAR
    + bool "Non linear mappings"
    + def_bool y
    + help
    + Provides support for the remap_file_pages syscall.
    +
    config MIGRATION
    bool "Page migration"
    def_bool y
    Index: linux-2.6/mm/Makefile
    ===================================================================
    --- linux-2.6.orig/mm/Makefile
    +++ linux-2.6/mm/Makefile
    @@ -3,9 +3,8 @@
    #

    mmu-y := nommu.o
    -mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \
    - mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
    - vmalloc.o
    +mmu-$(CONFIG_MMU) := highmem.o madvise.o memory.o mincore.o mlock.o \
    + mmap.o mprotect.o mremap.o msync.o rmap.o vmalloc.o

    obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
    page_alloc.o page-writeback.o pdflush.o \
    @@ -27,5 +26,6 @@ obj-$(CONFIG_SLOB) += slob.o
    obj-$(CONFIG_SLAB) += slab.o
    obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
    obj-$(CONFIG_FS_XIP) += filemap_xip.o
    +obj-$(CONFIG_NONLINEAR) += fremap.o
    obj-$(CONFIG_MIGRATION) += migrate.o
    obj-$(CONFIG_SMP) += allocpercpu.o
    Index: linux-2.6/mm/rmap.c
    ===================================================================
    --- linux-2.6.orig/mm/rmap.c
    +++ linux-2.6/mm/rmap.c
    @@ -756,6 +756,7 @@ out:
    return ret;
    }

    +#ifdef CONFIG_NONLINEAR
    /*
    * objrmap doesn't work for nonlinear VMAs because the assumption that
    * offset-into-file correlates with offset-into-virtual-addresses does not hold.
    @@ -845,53 +846,18 @@ static void try_to_unmap_cluster(unsigne
    pte_unmap_unlock(pte - 1, ptl);
    }

    -static int try_to_unmap_anon(struct page *page, int migration)
    -{
    - struct anon_vma *anon_vma;
    - struct vm_area_struct *vma;
    - int ret = SWAP_AGAIN;
    -
    - anon_vma = page_lock_anon_vma(page);
    - if (!anon_vma)
    - return ret;
    -
    - list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
    - ret = try_to_unmap_one(page, vma, migration);
    - if (ret == SWAP_FAIL || !page_mapped(page))
    - break;
    - }
    -
    - page_unlock_anon_vma(anon_vma);
    - return ret;
    -}
    -
    -/**
    - * try_to_unmap_file - unmap file page using the object-based rmap method
    - * @page: the page to unmap
    - *
    - * Find all the mappings of a page using the mapping pointer and the vma chains
    - * contained in the address_space struct it points to.
    - *
    - * This function is only called from try_to_unmap for object-based pages.
    +/*
    + * Called with page->mapping->i_mmap_lock held.
    */
    -static int try_to_unmap_file(struct page *page, int migration)
    +static int try_to_unmap_file_nonlinear(struct page *page, int migration)
    {
    struct address_space *mapping = page->mapping;
    - pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
    struct vm_area_struct *vma;
    - struct prio_tree_iter iter;
    - int ret = SWAP_AGAIN;
    unsigned long cursor;
    unsigned long max_nl_cursor = 0;
    unsigned long max_nl_size = 0;
    unsigned int mapcount;
    -
    - spin_lock(&mapping->i_mmap_lock);
    - vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
    - ret = try_to_unmap_one(page, vma, migration);
    - if (ret == SWAP_FAIL || !page_mapped(page))
    - goto out;
    - }
    + int ret = SWAP_AGAIN;

    if (list_empty(&mapping->i_mmap_nonlinear))
    goto out;
    @@ -956,6 +922,63 @@ static int try_to_unmap_file(struct page
    */
    list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
    vma->vm_private_data = NULL;
    +
    +out:
    + return ret;
    +}
    +
    +#else /* CONFIG_NONLINEAR */
    +static int try_to_unmap_file_nonlinear(struct page *page, int migration)
    +{
    + return SWAP_AGAIN;
    +}
    +#endif
    +
    +static int try_to_unmap_anon(struct page *page, int migration)
    +{
    + struct anon_vma *anon_vma;
    + struct vm_area_struct *vma;
    + int ret = SWAP_AGAIN;
    +
    + anon_vma = page_lock_anon_vma(page);
    + if (!anon_vma)
    + return ret;
    +
    + list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
    + ret = try_to_unmap_one(page, vma, migration);
    + if (ret == SWAP_FAIL || !page_mapped(page))
    + break;
    + }
    +
    + page_unlock_anon_vma(anon_vma);
    + return ret;
    +}
    +
    +/**
    + * try_to_unmap_file - unmap file page using the object-based rmap method
    + * @page: the page to unmap
    + *
    + * Find all the mappings of a page using the mapping pointer and the vma chains
    + * contained in the address_space struct it points to.
    + *
    + * This function is only called from try_to_unmap for object-based pages.
    + */
    +static int try_to_unmap_file(struct page *page, int migration)
    +{
    + struct address_space *mapping = page->mapping;
    + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
    + struct vm_area_struct *vma;
    + struct prio_tree_iter iter;
    + int ret = SWAP_AGAIN;
    +
    + spin_lock(&mapping->i_mmap_lock);
    + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
    + ret = try_to_unmap_one(page, vma, migration);
    + if (ret == SWAP_FAIL || !page_mapped(page))
    + goto out;
    + }
    +
    + ret = try_to_unmap_file_nonlinear(page, migration);
    out:
    spin_unlock(&mapping->i_mmap_lock);
    return ret;
    -
    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/
    \
     
     \ /
      Last update: 2007-03-07 10:03    [W:4.851 / U:0.176 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site