Messages in this thread | | | Date | Fri, 13 Jul 2012 13:43:33 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH 4/5] uprobes: kill copy_vma()->uprobe_mmap() |
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* Oleg Nesterov <oleg@redhat.com> [2012-07-08 22:30:08]:
> Kill copy_vma()->uprobe_mmap(new_vma), it is absolutely wrong. > > This new_vma was just initialized to represent the new unmapped area, > [vm_start, vm_end) was returned by get_unmapped_area() in the caller. > > This means that uprobe_mmap()->get_user_pages() will fail for sure, > simply because find_vma() can never succeed. And I verified that > sys_mremap()->mremap_to() indeed always fails with the wrong ENOMEM > code if [addr, addr+old_len] is probed. > > And why this uprobe_mmap() was added? I believe the intent was wrong. > Note that the caller is going to do move_page_tables(), all registered > uprobes are already faulted in, we only change the virtual addresses. > > NOTE: However, somehow we need to close the race with uprobe_register() > which relies on map_info->vaddr. This needs another fix I'll try to do > later. Probably we need uprobe_mmap() in move_vma() but we can not do > this right now, this can confuse uprobes_state.counter (which I still > hope we are going to kill). > > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> --- > mm/mmap.c | 3 --- > 1 files changed, 0 insertions(+), 3 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 3edfcdf..e5a4614 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -2418,9 +2418,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, > if (new_vma->vm_file) { > get_file(new_vma->vm_file); > > - if (uprobe_mmap(new_vma)) > - goto out_free_mempol; > - > if (vma->vm_flags & VM_EXECUTABLE) > added_exe_file_vma(mm); > } > -- > 1.5.5.1 >
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