Messages in this thread | | | From | KOSAKI Motohiro <> | Date | Tue, 16 Oct 2012 21:53:02 -0400 | Subject | Re: [patch for-3.7] mm, mempolicy: fix printing stack contents in numa_maps |
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On Tue, Oct 16, 2012 at 9:49 PM, David Rientjes <rientjes@google.com> wrote: > On Tue, 16 Oct 2012, KOSAKI Motohiro wrote: > >> > diff --git a/mm/mempolicy.c b/mm/mempolicy.c >> > index 0b78fb9..d04a8a5 100644 >> > --- a/mm/mempolicy.c >> > +++ b/mm/mempolicy.c >> > @@ -1536,9 +1536,8 @@ asmlinkage long compat_sys_mbind(compat_ulong_t start, compat_ulong_t len, >> > * >> > * Returns effective policy for a VMA at specified address. >> > * Falls back to @task or system default policy, as necessary. >> > - * Current or other task's task mempolicy and non-shared vma policies >> > - * are protected by the task's mmap_sem, which must be held for read by >> > - * the caller. >> > + * Current or other task's task mempolicy and non-shared vma policies must be >> > + * protected by task_lock(task) by the caller. >> >> This is not correct. mmap_sem is needed for protecting vma. task_lock() >> is needed to close vs exit race only when task != current. In other word, >> caller must held both mmap_sem and task_lock if task != current. > > The comment is specifically addressing non-shared vma policies, you do not > need to hold mmap_sem to access another thread's mempolicy.
I didn't say old comment is true. I just only your new comment also false.
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