Messages in this thread | | | Date | Fri, 4 Nov 2005 22:38:10 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 6/5] cpuset: rebind numa vma mempolicy fix |
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Paul Jackson <pj@sgi.com> wrote: > > It's ok to not complete the refresh_mems() operation > if we notice we are already holding mmap_sem. We > will try again, next time we allocate memory.
What's the call path? alloc_pages_current() and alloc_page_vma()?
> > --- 2.6.14-rc5-mm1-cpuset-patches.orig/kernel/cpuset.c 2005-11-03 21:18:26.783391082 -0800 > +++ 2.6.14-rc5-mm1-cpuset-patches/kernel/cpuset.c 2005-11-03 23:11:15.480042373 -0800 > @@ -656,7 +656,12 @@ static void refresh_mems(void) > if (current->cpuset_mems_generation != my_cpusets_mem_gen) { > struct cpuset *cs; > nodemask_t oldmem = current->mems_allowed; > + struct mm_struct *mm = current->mm; > > + /* numa_policy_rebind() needs mmap_sem - don't nest */ > + if (!mm || !down_write_trylock(&mm->mmap_sem)) > + return; > + up_write(&mm->mmap_sem);
What happens if the task is doing _all_ its allocation under down_read(mmap_sem)? Like, memset(malloc(lots))? Does all that memory end up in the wrong place, or what?
Something less hacky^W^W more deterministic would be nice. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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