From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Schwidefsky Subject: Re: [PATCH] s390: Add pmd_mknotpresent() Date: Mon, 29 Oct 2012 12:30:06 +0100 Message-ID: <20121029123006.5eae86ea@mschwide> References: <20121018172201.b81dcc8fe40868256f532364@canb.auug.org.au> <20121018182642.2a541275@thinkpad> <20121028131014.GA10754@gmail.com> <20121029084956.12b512e6@mschwide> <20121029110519.GA22569@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:50957 "EHLO e06smtp12.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758744Ab2J2LaT (ORCPT ); Mon, 29 Oct 2012 07:30:19 -0400 Received: from /spool/local by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 29 Oct 2012 11:30:17 -0000 In-Reply-To: <20121029110519.GA22569@gmail.com> Sender: linux-next-owner@vger.kernel.org List-ID: To: Ingo Molnar Cc: Gerald Schaefer , Stephen Rothwell , Heiko Carstens , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Ralf Baechle , Peter Zijlstra On Mon, 29 Oct 2012 12:05:19 +0100 Ingo Molnar wrote: > > * Martin Schwidefsky wrote: > > > On Sun, 28 Oct 2012 14:10:14 +0100 > > Ingo Molnar 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 --- 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.