On 4/9/20 6:18 PM, Peter Xu wrote: > On Thu, Apr 09, 2020 at 03:08:07PM -0700, Mike Kravetz wrote: >> On 4/9/20 2:58 PM, Peter Xu wrote: >>> The hugepage options are not documented clearly. >>> >>> Firstly, default_hugepagesz= should always be specified after the >>> declaration of the same type of huge page using hugepagesz=. For >>> example, if we boot a x86_64 system with kernel cmdline >>> "default_hugepagesz=2M", we'll get a very funny error message: >>> >>> "HugeTLB: unsupported default_hugepagesz 2097152. Reverting to 2097152" >>> >>> It's understandable from code-wise because when hugetlb_init() we >>> didn't have the 2M page hstate registered, so it's unsupported. >>> However 2M is actually the default huge page size on x86_64, so we'll >>> register it right after the error message. However it's very >>> confusing if without these knowledges. >>> >>> Secondly, hugepages= option must be used _after_ another hugepagesz=. >>> The word "interleave" is fine but it didn't declare the fact that >>> each of the hugepages= option will be applied to the previous parsed >>> hugepagesz= option. >>> >>> State all these clear. >>> >>> Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> >> Hi Peter, >> >> Did you happen to see this patch series? >> >> https://lore.kernel.org/linux-mm/20200401183819.20647-1-mike.kravetz@xxxxxxxxxx/ >> >> That should address the documentation issue and more. > Great! > > I missed that, but I'll definitely read it (probably tomorrow). Let's > ignore this patch then. My bad, I didn't realize that Mike has already pointed you in the right direction. Please ignore my earlier email. :) > > Thanks, > -- Nitesh
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