As Christian pointed out, the recent 'Revert "thp: make MADV_HUGEPAGE check for mm->def_flags"' breaks qemu, it does QEMU_MADV_HUGEPAGE for all kvm pages but this doesn't work after s390_enable_sie/thp_split_mm.
Paolo suggested that instead of failing on the call to madvise, we simply ignore the call (return 0). Reported-by: Christian Borntraeger <[email protected]> Suggested-by: Paolo Bonzini <[email protected]> Suggested-by: Oleg Nesterov <[email protected]> Signed-off-by: Alex Thorlton <[email protected]> Cc: Gerald Schaefer <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: Christian Borntraeger <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: "Eric W. Biederman" <[email protected]> Cc: Alexander Viro <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] --- mm/huge_memory.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index a4310a5..61d234d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1970,6 +1970,15 @@ int hugepage_madvise(struct vm_area_struct *vma, { switch (advice) { case MADV_HUGEPAGE: +#ifdef CONFIG_S390 + /* + * qemu blindly sets MADV_HUGEPAGE on all allocations, but s390 + * can't handle this properly after s390_enable_sie, so we simply + * ignore the madvise to prevent qemu from causing a SIGSEGV. + */ + if (mm_has_pgste(vma->vm_mm)) + return 0; +#endif /* * Be somewhat over-protective like KSM for now! */ -- 1.7.12.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
