On 09/26/2013 11:48 PM, Tejun Heo wrote: > On Thu, Sep 26, 2013 at 11:43:02PM +0800, Zhang Yanfei wrote: >>> As Yinghai pointed out in another thread, do we need to worry about >>> falling back to top-down? >> >> I've explained to him. Nop, we don't need to worry about that. Because even >> the min_pfn_mapped becomes ISA_END_ADDRESS in the second call below, we won't >> allocate memory below the kernel because we have limited the allocation above >> the kernel. > > Maybe I misunderstood but wasn't he worrying about there not being > enough space above kernel? In that case, it'd automatically fall back > to top-down allocation anyway, right? Ah, I see. You are saying another issue. He is worrying that if we use kexec to load the kernel high, say we have 16GB, we put the kernel in 15.99GB (just an example), so we only have less than 100MB above the kernel. But as I've explained to him, in almost all the cases, if we want our memory hotplug work, we don't do that. And yeah, assume we have this problem, it'd fall back to top down and that return backs to patch 2, we will trigger the WARN_ONCE, and the admin will know what has happened. Thanks. -- Thanks. Zhang Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
