[<prev] [next>] [day] [month] [year] [list]
Message-Id: <20060826174249.14790.91862.stgit@memento.home.lan>
Date: Sat, 26 Aug 2006 19:42:49 +0200
From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@...oo.it>
To: Andrew Morton <akpm@...l.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH RFP-V4 12/13] RFP prot support: also set VM_NONLINEAR on nonuniform VMAs
From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@...oo.it>
To simplify the VM code, and to reflect expected application usage, we decide
to also set VM_NONLINEAR when setting VM_MANYPROTS. Otherwise, we'd have to
possibly save nonlinear PTEs even on paths which cope with linear VMAs. It's
possible, but intrusive (it's done in one of the next patches).
Obviously, this has a performance cost, since we potentially have to handle a
linear VMA with nonlinear handling code. But I didn't know of any application
which might have this usage.
XXX: update: glibc wants to replace mprotect() with linear VM_MANYPROTS areas,
to handle guard pages and data mappings of shared objects.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@...oo.it>
---
mm/fremap.c | 27 ++++++++++++++-------------
1 files changed, 14 insertions(+), 13 deletions(-)
diff --git a/mm/fremap.c b/mm/fremap.c
index b1db410..3438caf 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -213,8 +213,9 @@ retry:
if (!vma->vm_private_data || (vma->vm_flags & VM_NONLINEAR)) {
/* Must set VM_NONLINEAR before any pages are populated. */
- if (pgoff != linear_page_index(vma, start) &&
- !(vma->vm_flags & VM_NONLINEAR)) {
+ if (!(vma->vm_flags & VM_NONLINEAR) &&
+ (pgoff != linear_page_index(vma, start) ||
+ pgprot_val(pgprot) != pgprot_val(vma->vm_page_prot))) {
if (!(vma->vm_flags & VM_SHARED))
goto out_unlock;
if (!has_write_lock) {
@@ -231,19 +232,19 @@ retry:
vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
flush_dcache_mmap_unlock(mapping);
spin_unlock(&mapping->i_mmap_lock);
- }
- if (pgprot_val(pgprot) != pgprot_val(vma->vm_page_prot) &&
- !(vma->vm_flags & VM_MANYPROTS)) {
- if (!(vma->vm_flags & VM_SHARED))
- goto out_unlock;
- if (!has_write_lock) {
- up_read(&mm->mmap_sem);
- down_write(&mm->mmap_sem);
- has_write_lock = 1;
- goto retry;
+ if (!(vma->vm_flags & VM_MANYPROTS) &&
+ pgprot_val(pgprot) != pgprot_val(vma->vm_page_prot)) {
+ if (!(vma->vm_flags & VM_SHARED))
+ goto out_unlock;
+ if (!has_write_lock) {
+ up_read(&mm->mmap_sem);
+ down_write(&mm->mmap_sem);
+ has_write_lock = 1;
+ goto retry;
+ }
+ vma->vm_flags |= VM_MANYPROTS;
}
- vma->vm_flags |= VM_MANYPROTS;
}
err = vma->vm_ops->populate(vma, start, size, pgprot, pgoff,
Chiacchiera con i tuoi amici in tempo reale!
http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists