• Hugh Dickins's avatar
    [PATCH] unpaged: VM_UNPAGED · 0b14c179
    Hugh Dickins authored
    Although we tend to associate VM_RESERVED with remap_pfn_range, quite a few
    drivers set VM_RESERVED on areas which are then populated by nopage.  The
    PageReserved removal in 2.6.15-rc1 changed VM_RESERVED not to free pages in
    zap_pte_range, without changing those drivers not to set it: so their pages
    just leak away.
    
    Let's not change miscellaneous drivers now: introduce VM_UNPAGED at the core,
    to flag the special areas where the ptes may have no struct page, or if they
    have then it's not to be touched.  Replace most instances of VM_RESERVED in
    core mm by VM_UNPAGED.  Force it on in remap_pfn_range, and the sparc and
    sparc64 io_remap_pfn_range.
    
    Revert addition of VM_RESERVED to powerpc vdso, it's not needed there.  Is it
    needed anywhere?  It still governs the mm->reserved_vm statistic, and special
    vmas not to be merged, and areas not to be core dumped; but could probably be
    eliminated later (the drivers are probably specifying it because in 2.4 it
    kept swapout off the vma, but in 2.6 we work from the LRU, which these pages
    don't get on).
    
    Use the VM_SHM slot for VM_UNPAGED, and define VM_SHM to 0: it serves no
    purpose whatsoever, and should be removed from drivers when we clean up.
    Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
    Acked-by: default avatarWilliam Irwin <wli@holomorphy.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    0b14c179
madvise.c 7.17 KB