On Thu, 16 Aug 2007, Paul Mackerras wrote:

Herbert Xu writes:

quoted

It doesn't matter.  The memory pressure flag is an *advisory*
flag.  If we get it wrong the worst that'll happen is that we'd
waste some time doing work that'll be thrown away.

Ah, so it's the "racy but I don't care because it's only an
optimization" case.  That's fine.  Somehow I find it hard to believe
that all the racy uses of atomic_read in the kernel are like that,
though. :)

My use of atomic_read in SLUB is like that. Volatile does not magically 
sync up reads somehow.