From: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]> For linear VMA's, there is no need to install pte_file PTEs to remember the offset. We could probably go as far as checking directly the address and protection like in include/linux/pagemap.h:set_nonlinear_pte(), instead of vma->vm_flags. Also add some warnings on the path which used to cope with such PTE's.
Untested yet. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]> --- linux-2.6.git-paolo/mm/fremap.c | 12 ++++++------ linux-2.6.git-paolo/mm/memory.c | 5 +++++ 2 files changed, 11 insertions(+), 6 deletions(-) diff -puN mm/fremap.c~rfp-linear-optim-v3 mm/fremap.c --- linux-2.6.git/mm/fremap.c~rfp-linear-optim-v3 2005-08-11 23:20:09.000000000 +0200 +++ linux-2.6.git-paolo/mm/fremap.c 2005-08-11 23:20:09.000000000 +0200 @@ -125,6 +125,12 @@ int install_file_pte(struct mm_struct *m BUG_ON(!uniform && !(vma->vm_flags & VM_SHARED)); + /* We're being called by mmap(MAP_NONBLOCK|MAP_POPULATE) on an uniform + * VMA. So don't need to take the lock, and to install a PTE for the + * page we'd fault in anyway. */ + if (uniform) + return 0; + pgd = pgd_offset(mm, addr); spin_lock(&mm->page_table_lock); @@ -139,12 +145,6 @@ int install_file_pte(struct mm_struct *m pte = pte_alloc_map(mm, pmd, addr); if (!pte) goto err_unlock; - /* - * Skip uniform non-existent ptes: - */ - err = 0; - if (uniform && pte_none(*pte)) - goto err_unlock; zap_pte(mm, vma, addr, pte); diff -puN mm/memory.c~rfp-linear-optim-v3 mm/memory.c --- linux-2.6.git/mm/memory.c~rfp-linear-optim-v3 2005-08-11 23:20:09.000000000 +0200 +++ linux-2.6.git-paolo/mm/memory.c 2005-08-11 23:20:09.000000000 +0200 @@ -1969,9 +1969,14 @@ static int do_file_page(struct mm_struct /* * Fall back to the linear mapping if the fs does not support * ->populate; in this case do the protection checks. + * Could have been installed by install_file_pte, for a MAP_NONBLOCK + * pagetable population. */ if (!vma->vm_ops->populate || ((access_mask & VM_WRITE) && !(vma->vm_flags & VM_SHARED))) { + /* remap_file_pages should disallow this, now that + * install_file_pte skips linear ones. */ + WARN_ON(1); /* We're behaving as if pte_file was cleared, so check * protections like in handle_pte_fault. */ if (check_perms(vma, access_mask)) _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/