This reverts commit 8e72033f2a489b6c98c4e3c7cc281b1afd6cb85c, and adds in code to fix up any issues caused by the revert.
The revert is necessary because hugepage_madvise would return -EINVAL when VM_NOHUGEPAGE is set, which will break subsequent chunks of this patch set. Here's a snip of an e-mail from Gerald detailing the original purpose of this code, and providing justification for the revert: <snip> The intent of 8e72033f2a48 was to guard against any future programming errors that may result in an madvice(MADV_HUGEPAGE) on guest mappings, which would crash the kernel. Martin suggested adding the bit to arch/s390/mm/pgtable.c, if 8e72033f2a48 was to be reverted, because that check will also prevent a kernel crash in the case described above, it will now send a SIGSEGV instead. This would now also allow to do the madvise on other parts, if needed, so it is a more flexible approach. One could also say that it would have been better to do it this way right from the beginning... </snip> Signed-off-by: Alex Thorlton <[email protected]> Suggested-by: Oleg Nesterov <[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] --- arch/s390/mm/pgtable.c | 3 +++ mm/huge_memory.c | 4 ---- 2 files changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 3584ed9..a87cdb4 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -504,6 +504,9 @@ static int gmap_connect_pgtable(unsigned long address, unsigned long segment, if (!pmd_present(*pmd) && __pte_alloc(mm, vma, pmd, vmaddr)) return -ENOMEM; + /* large pmds cannot yet be handled */ + if (pmd_large(*pmd)) + return -EFAULT; /* pmd now points to a valid segment table entry. */ rmap = kmalloc(sizeof(*rmap), GFP_KERNEL|__GFP_REPEAT); if (!rmap) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 82166bf..a4310a5 100644 --- a/mm/huge_memory.c +++ b/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 +1975,6 @@ int hugepage_madvise(struct vm_area_struct *vma, */ if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) return -EINVAL; - if (mm->def_flags & VM_NOHUGEPAGE) - return -EINVAL; *vm_flags &= ~VM_NOHUGEPAGE; *vm_flags |= VM_HUGEPAGE; /* -- 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/
