Messages in this thread Patch in this message | | | Subject | [patch 14/39] remap_file_pages protection support: assume VM_SHARED never disappears | From | blaisorblade@yahoo ... | Date | Fri, 12 Aug 2005 19:32:05 +0200 |
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From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Assume that even after dropping and reacquiring the lock, (vma->vm_flags & VM_SHARED) won't change, thus moving a check earlier.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> ---
linux-2.6.git-paolo/mm/fremap.c | 12 ++---------- 1 files changed, 2 insertions(+), 10 deletions(-)
diff -puN mm/fremap.c~rfp-assume-VM_PRIVATE-stays mm/fremap.c --- linux-2.6.git/mm/fremap.c~rfp-assume-VM_PRIVATE-stays 2005-08-11 12:58:07.000000000 +0200 +++ linux-2.6.git-paolo/mm/fremap.c 2005-08-11 13:38:56.000000000 +0200 @@ -232,6 +232,8 @@ retry: /* Must set VM_NONLINEAR before any pages are populated. */ if (pgoff != linear_page_index(vma, start)) { + if (!(vma->vm_flags & VM_SHARED)) + goto out_unlock; if (!(vma->vm_flags & VM_NONLINEAR)) { if (!has_write_lock) { up_read(&mm->mmap_sem); @@ -239,12 +241,6 @@ retry: 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); @@ -254,10 +250,6 @@ retry: 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; } } _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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