On 14/09/16 20:40, santhosh wrote: > >> Michael Ellerman <m...@ellerman.id.au> writes: >> >>> On Fri, 2016-19-02 at 05:38:47 UTC, Rashmica Gupta wrote: >>>> Currently on PPC64 changing kernel pagesize from 4K to 64K leaves >>>> FORCE_MAX_ZONEORDER set to 13 - which produces a compile error. >>>> >>> ... >>>> So, update the range of FORCE_MAX_ZONEORDER from 9-64 to 8-9 for 64K pages >>>> and from 13-64 to 9-13 for 4K pages. >>>> >>>> Signed-off-by: Rashmica Gupta <rashm...@gmail.com> >>>> Reviewed-by: Balbir Singh <bsinghar...@gmail.com> >>> Applied to powerpc next, thanks. >>> >>> https://git.kernel.org/powerpc/c/a7ee539584acf4a565b7439cea >>> >> HPAGE_PMD_ORDER is not something we should check w.r.t 4k linux page >> size. We do have the below constraint w.r.t hugetlb pages >> >> static inline bool hstate_is_gigantic(struct hstate *h) >> { >> return huge_page_order(h) >= MAX_ORDER; >> } >> >> That require MAX_ORDER to be greater than 12. >>
9 to 13 was done based on calculations you can find the commit >> Did we test hugetlbfs 4k config with this patch ? Will it work if we >> start marking hugepage as gigantic page ? >> >> -aneesh >> > Hello Rashmica, > > With upstream linux kernel 4.8.0-rc1-00006-gbae9cc6 compiled with linux 4k > page size we are not able set hugepages, Aneesh had a look at the problem and > he mentioned this commit is causing the issue. > > *Details:* > We are using pkvm ubuntu 16.04 guest with upstream kernel > [4.8.0-rc1-00006-gbae9cc6] compiled with 4k page size > > o/p from guest: > HugePages_Total: 0 > HugePages_Free: 0 > HugePages_Rsvd: 0 > HugePages_Surp: 0 > Hugepagesize: 16384 kB > > Page sizes from device-tree: [dmesg] > [ 0.000000] base_shift=12: shift=12, sllp=0x0000, avpnm=0x00000000, > tlbiel=1, penc=0 > [ 0.000000] base_shift=12: shift=24, sllp=0x0000, avpnm=0x00000000, > tlbiel=1, penc=56 > [ 0.000000] base_shift=24: shift=24, sllp=0x0100, avpnm=0x00000001, > tlbiel=0, penc=0 > > while trying to configure the hugepages inside the guest it throws the below > error: > > echo 100 > /proc/sys/vm/nr_hugepages > -bash: echo: write error: Invalid argument > > *Note*: we do not see the problem when the linux page is 64k Just to reiterate you are seeing this problem using 4k page size and 16M as the hugepage size. With FORCE_MAX_ZONEORDER set to 9 to 13 for 4k pages, you can do upto 32M if FORCE_MAX_ZONEORDER is 13 and same for 64K with FORCE_MAX_ZONEORDER set to 9. Basically the constraint is FORCE_MAX_ZONEBITS <= 25 - PAGESHIFT What is your value of FORCE_MAX_ZONEORDER in the .config? Balbir Singh.
