Re: [PATCH 6/7] mm: kill vma flag VM_EXECUTABLE

[Konstantin Khlebnikov]

Oleg Nesterov wrote:
> On 04/02, Konstantin Khlebnikov wrote:
> > In this patch I leave mm->exe_file lockless.
> > After exec/fork we can change it only for current task and only if mm->mm_users == 1.
> >
> > something like this:
> >
> > task_lock(current);
>
> OK, this protects against the race with get_task_mm()
>
> > if (atomic_read(&current->mm->mm_users) == 1)
>
> this means PR_SET_MM_EXE_FILE can fail simply because someone did
> get_task_mm(). Or the caller is multithreaded.

This is sad, seems like we should keep mm->exe_file protection by mm->mmap_sem.
So, I'll rework this patch...

> > 	set_mm_exe_file(current->mm, new_file);
>
> No, fput() can sleep.

Yep

> Oleg.
>
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