On Thu, 14 Jul 2016, David Rientjes wrote:
> On Thu, 14 Jul 2016, Tetsuo Handa wrote: > > > David Rientjes wrote: > > > On Wed, 13 Jul 2016, Mikulas Patocka wrote: > > > > > > > What are the real problems that > > > > f9054c70d28bc214b2857cf8db8269f4f45a5e23 > > > > tries to fix? > > > > > > > > > > It prevents the whole system from livelocking due to an oom killed > > > process > > > stalling forever waiting for mempool_alloc() to return. No other threads > > > may be oom killed while waiting for it to exit. > > > > Is that concern still valid? We have the OOM reaper for CONFIG_MMU=y case. > > > > Umm, show me an explicit guarantee where the oom reaper will free memory > such that other threads may return memory to this process's mempool so it > can make forward progress in mempool_alloc() without the need of utilizing > memory reserves. First, it might be helpful to show that the oom reaper > is ever guaranteed to free any memory for a selected oom victim. The function mempool_alloc sleeps with "io_schedule_timeout(5*HZ);" So, if the oom reaper frees some memory into the page allocator, the process that is stuck in mempoo_alloc will sleep for up to 5 seconds, then it will retry the allocation with "element = pool->alloc(gfp_temp, pool->pool_data)" (that will allocate from the page allocator) and succed. Mikulas
