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))
_
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