On Mon, 29 Oct 2012 12:05:19 +0100 Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > * Martin Schwidefsky <schwidefsky@xxxxxxxxxx> wrote: > > > On Sun, 28 Oct 2012 14:10:14 +0100 > > Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > > > > > > > There's a related problem on s390: other THP implementations > > > have pmd_mknotpresent() while s390 not, resulting in: > > > > > > mm/huge_memory.c:1543:2: error: implicit declaration of function 'pmd_mknotpresent' > > > > > > The (untested!) patch below adds the s390 version of this > > > method. > > > > > > Gerald, Martin, did I get the S390 details right? > > > > This won't work I'm afraid. S390 uses invalid bits which need > > to be set to make an entry not present. Just setting the > > _SEGMENT_ENTRY_INV bit is not good enough either, there is > > _HPAGE_TYPE_NONE to consider. The patch to fix this for > > pmd_none & pmd_present just got added to the s390 tree on > > kernel.org: > > > > https://git.kernel.org/?p=linux/kernel/git/s390/linux.git;a=shortlog;h=refs/heads/fixes > > > > Now, if pmd_mknotpresent is supposed to make the entry invalid > > so that pmd_present will return false the function needs to do > > two things, 1) set the _SEGMENT_ENTRY_INV bit, and 2) clear > > the _SEGMENT_ENTRY_RO bit. > > Would be nice if you could send me your suggested > pmd_mknotpresent(). > > (Writing it into the email would be enough, I can turn it into a > patch - but a patch would be welcome as well.) This would look like the following, the patch should apply to all recent kernel version. -- Subject: [PATCH] s390,mm: add pmd_mknotpresent Fix the following build problem in huge_memory: mm/huge_memory.c:1543:2: error: implicit declaration of function 'pmd_mknotpresent' Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> --- arch/s390/include/asm/pgtable.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 335b601..4a84431 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1326,6 +1326,13 @@ static inline pmd_t pmd_mkyoung(pmd_t pmd) return pmd; } +static inline pmd_t pmd_mknotpresent(pmd_t pmd) +{ + pmd_val(pmd) |= _SEGMENT_ENTRY_INV; + pmd_val(pmd) &= ~_SEGMENT_ENTRY_RO; + return pmd; +} + #define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp) -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
