From: Ingo Molnar <[email protected]>
If we're not rearranging pages, support even PRIVATE vma.
This is needed to make MAP_POPULATE|MAP_PRIVATE to work, since it calls
remap_file_pages.
Notes from: Paolo 'Blaisorblade' Giarrusso <[email protected]>
We don't support private VMA because when they're swapped out we need to store
the swap entry in the PTE, not the file offset and protections; so, I suppose
that with remap-file-pages-prot, we must punt on private VMA even when we're
just changing protections. This change is in a separate patch.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <[email protected]>
---
linux-2.6.git-paolo/mm/fremap.c | 55 ++++++++++++++++++++++++----------------
linux-2.6.git-paolo/mm/mmap.c | 4 ++
2 files changed, 38 insertions(+), 21 deletions(-)
diff -puN mm/fremap.c~rfp-private-vma mm/fremap.c
--- linux-2.6.git/mm/fremap.c~rfp-private-vma 2005-08-11 23:02:45.000000000 +0200
+++ linux-2.6.git-paolo/mm/fremap.c 2005-08-11 23:02:45.000000000 +0200
@@ -218,34 +218,47 @@ retry:
goto out_unlock;
if (((prot & PROT_EXEC) && !(vma->vm_flags & VM_MAYEXEC)))
goto out_unlock;
+ err = -EINVAL;
pgprot = protection_map[calc_vm_prot_bits(prot) | VM_SHARED];
} else
pgprot = vma->vm_page_prot;
- if ((vma->vm_flags & VM_SHARED) &&
- (!vma->vm_private_data ||
- (vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) &&
- vma->vm_ops && vma->vm_ops->populate &&
- end > start && start >= vma->vm_start &&
- end <= vma->vm_end) {
+ if (!vma->vm_ops || !vma->vm_ops->populate || end <= start || start <
+ vma->vm_start || end > vma->vm_end)
+ goto out_unlock;
+
+ if (!vma->vm_private_data ||
+ (vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) {
/* Must set VM_NONLINEAR before any pages are populated. */
- if (pgoff != linear_page_index(vma, start) &&
- !(vma->vm_flags & VM_NONLINEAR)) {
- if (!has_write_lock) {
- up_read(&mm->mmap_sem);
- down_write(&mm->mmap_sem);
- has_write_lock = 1;
- goto retry;
+ if (pgoff != linear_page_index(vma, start)) {
+ if (!(vma->vm_flags & VM_NONLINEAR)) {
+ if (!has_write_lock) {
+ up_read(&mm->mmap_sem);
+ down_write(&mm->mmap_sem);
+ has_write_lock = 1;
+ goto retry;
+ }
+ /* XXX: we check VM_SHARED after re-getting the
+ * (write) semaphore but I guess that we could
+ * check it earlier as we're not allowed to turn
+ * a VM_PRIVATE vma into a VM_SHARED one! */
+ if (!(vma->vm_flags & VM_SHARED))
+ goto out_unlock;
+
+ mapping = vma->vm_file->f_mapping;
+ spin_lock(&mapping->i_mmap_lock);
+ flush_dcache_mmap_lock(mapping);
+ vma->vm_flags |= VM_NONLINEAR;
+ vma_prio_tree_remove(vma, &mapping->i_mmap);
+ vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
+ flush_dcache_mmap_unlock(mapping);
+ spin_unlock(&mapping->i_mmap_lock);
+ } else {
+ /* Won't drop the lock, check it here.*/
+ if (!(vma->vm_flags & VM_SHARED))
+ goto out_unlock;
}
- mapping = vma->vm_file->f_mapping;
- spin_lock(&mapping->i_mmap_lock);
- flush_dcache_mmap_lock(mapping);
- vma->vm_flags |= VM_NONLINEAR;
- vma_prio_tree_remove(vma, &mapping->i_mmap);
- vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
- flush_dcache_mmap_unlock(mapping);
- spin_unlock(&mapping->i_mmap_lock);
}
err = vma->vm_ops->populate(vma, start, size, pgprot, pgoff,
diff -puN mm/mmap.c~rfp-private-vma mm/mmap.c
--- linux-2.6.git/mm/mmap.c~rfp-private-vma 2005-08-11 23:02:45.000000000 +0200
+++ linux-2.6.git-paolo/mm/mmap.c 2005-08-11 23:02:45.000000000 +0200
@@ -1120,6 +1120,10 @@ out:
}
if (flags & MAP_POPULATE) {
up_write(&mm->mmap_sem);
+ /*
+ * remap_file_pages() works even if the mapping is private,
+ * in the linearly-mapped case:
+ */
sys_remap_file_pages(addr, len, 0,
pgoff, flags & MAP_NONBLOCK);
down_write(&mm->mmap_sem);
_
-
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/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
| |
 |