Messages in this thread | | | Date | Sun, 9 Mar 2008 12:14:56 +0100 | From | Ingo Molnar <> | Subject | Re: quicklists confuse meminfo |
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* Thomas Gleixner <tglx@linutronix.de> wrote:
> Bart reported http://bugzilla.kernel.org/show_bug.cgi?id=9991. He > assumed a memory leak in 32bit kernels when he analyzed the output of > /proc/meminfo. > > The leak is not a leak, it's an accounting bug. quicklists keep a > large amount of pages which are accounted as used memory. [...] > Another strange observation about quicklists is the imbalance of the > quicklists across CPUs. Running the above loop on a 2way machine I can > observe that the quicklist pages are acuumulating on one CPU. Stopping > and restarting the loop a couple of times can shift the accumulation > from one to the other CPU.
hm. I think we should not let this much RAM hang around in a special-purpose allocator like quicklists. Shouldnt the quicklists be temporary in nature, and be trimmed much more agressively?
in fact, we have a check_pgt_cache() call in cpu_idle(), which does:
quicklist_trim(0, pgd_dtor, 25, 16);
but it appears we dont do quicklist trimming anywhere else! So if a system has no idle time, the quicklist can grow unbounded, and that's a real memory leak IMO.
Ingo
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