Messages in this thread | | | From | "Kirill A. Shutemov" <> | Subject | Re: + mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch added to -mm tree | Date | Wed, 26 Feb 2014 17:22:35 +0200 (EET) |
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Christian Borntraeger wrote: > On 26/02/14 15:50, Oleg Nesterov wrote: > [...] > > >> NAK. > >> > >> Since 2012 qemu does call "qemu_madvise(new_block->host, size, QEMU_MADV_HUGEPAGE);" for all kvm pages. > >> (commit ad0b5321f1f797274603ebbe20108b0750baee94 Call MADV_HUGEPAGE for guest RAM allocations) so this > >> breaks any recent kvm guest on s390. > > > > Well, I can't really discuss the changes in arch/s390. > > > > But perhaps qemu can be changed to avoid MADV_HUGEPAGE on s390 ? > > Otherwise I'd suggest the change below. > > > > Oleg. > > > > > > --- x/mm/huge_memory.c > > +++ x/mm/huge_memory.c > > @@ -1968,8 +1968,6 @@ out: > > int hugepage_madvise(struct vm_area_struct *vma, > > unsigned long *vm_flags, int advice) > > { > > - struct mm_struct *mm = vma->vm_mm; > > - > > switch (advice) { > > case MADV_HUGEPAGE: > > /* > > @@ -1977,8 +1975,16 @@ int hugepage_madvise(struct vm_area_stru > > */ > > if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) > > return -EINVAL; > > - if (mm->def_flags & VM_NOHUGEPAGE) > > + > > +/* > > + * MADV_HUGEPAGE after PRCTL_THP_DISABLE is broken on s390 because > > + * qemu blindly does madvise(MADV_HUGEPAGE) after s390_enable_sie(). > > + */ > > +#ifdef CONFIG_S390 > > + if (vma->vm_mm->def_flags & VM_NOHUGEPAGE) > > return -EINVAL; > > +#endif > > + > > Ifdefs are ugly
IS_ENABLED(CONFIG_S390) should help with this.
-- Kirill A. Shutemov
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