Messages in this thread | | | Date | Tue, 15 Jun 2010 10:04:24 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH 12/12] vmscan: Do not writeback pages in direct reclaim |
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On 06/15/2010 09:59 AM, Mel Gorman wrote: > On Tue, Jun 15, 2010 at 09:34:18AM -0400, Rik van Riel wrote: >> On 06/15/2010 07:45 AM, Mel Gorman wrote:
>>>>> >>>>> +/* kswapd and memcg can writeback as they are unlikely to overflow stack */ >>>>> +static inline bool reclaim_can_writeback(struct scan_control *sc) >>>>> +{ >>>>> + return current_is_kswapd() || sc->mem_cgroup != NULL; >>>>> +}
>> If direct reclaim can overflow the stack, so can direct >> memcg reclaim. That means this patch does not solve the >> stack overflow, while admitting that we do need the >> ability to get specific pages flushed to disk from the >> pageout code. >> > > What path is taken with memcg != NULL that could overflow the stack? I > couldn't spot one but mm/memcontrol.c is a bit tangled so finding all > its use cases is tricky. The critical path I had in mind though was > direct reclaim and for that path, memcg == NULL or did I miss something?
mem_cgroup_hierarchical_reclaim -> try_to_free_mem_cgroup_pages
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