Re: BUG FIX?: mm->rss is modified in some places without holding the page_table_lock

From: Theodore Y. Ts'o (tytso@MIT.EDU)
Date: Fri Nov 03 2000 - 09:56:15 EST


   Date: Fri, 3 Nov 2000 03:33:37 -0800
   From: "David S. Miller" <davem@redhat.com>

      Given that we don't have a 64-bit atomic_t type, what do people
      think of Davej's patch? (attached, below)

   Broken, in 9 out of 10 places where he adds page_table_lock
   acquisitions, this lock is already held --> instant deadlock.

   This report is complicated by the fact that people were forgetting
   that vmlist_*_{lock,unlock}(mm) was actually just spin_{lock,unlock}
   on mm->page_table_lock. I fixed that already by removing the dumb
   vmlist locking macros which were causing all of this confusion.

Are you saying that the original bug report may not actually be a
problem? Is ms->rss actually protected in _all_ of the right places, but
people got confused because of the syntactic sugar?

                                                - Ted
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