Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964961AbWLTLnn (ORCPT ); Wed, 20 Dec 2006 06:43:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964965AbWLTLnn (ORCPT ); Wed, 20 Dec 2006 06:43:43 -0500 Received: from amsfep15-int.chello.nl ([62.179.120.10]:64417 "EHLO amsfep15-int.chello.nl" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S964961AbWLTLnm (ORCPT ); Wed, 20 Dec 2006 06:43:42 -0500 Subject: Re: [PATCH] mm: fix page_mkclean_one (was: 2.6.19 file content corruption on ext3) From: Peter Zijlstra To: Jesper Juhl Cc: Arjan van de Ven , Linus Torvalds , Andrei Popa , Andrew Morton , Linux Kernel Mailing List , Hugh Dickins , Florian Weimer , Marc Haber , Martin Michlmayr , Martin Schwidefsky , Heiko Carstens , Arnd Bergmann In-Reply-To: <9a8748490612200339x4b50f0e1i3da4313bea85fbc6@mail.gmail.com> References: <1166314399.7018.6.camel@localhost> <1166468651.6983.6.camel@localhost> <1166471069.6940.4.camel@localhost> <1166571749.10372.178.camel@twins> <1166605296.10372.191.camel@twins> <1166607554.3365.1354.camel@laptopd505.fenrus.org> <1166614001.10372.205.camel@twins> <9a8748490612200339x4b50f0e1i3da4313bea85fbc6@mail.gmail.com> Content-Type: text/plain Date: Wed, 20 Dec 2006 12:42:19 +0100 Message-Id: <1166614939.10372.208.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2918 Lines: 76 On Wed, 2006-12-20 at 12:39 +0100, Jesper Juhl wrote: > On 20/12/06, Peter Zijlstra wrote: > > > > fix page_mkclean_one() > > > > it had several issues: > > - it failed to flush the cache > > - it failed to flush the tlb > > - it failed to do s390 (s390 guys, please verify this is now correct) > > > > Also, clear in a loop to ensure SMP safeness as suggested by Arjan. > > > > Signed-off-by: Peter Zijlstra > > --- > > mm/rmap.c | 29 +++++++++++++++-------------- > > 1 file changed, 15 insertions(+), 14 deletions(-) > > > > Index: linux-2.6/mm/rmap.c > > =================================================================== > > --- linux-2.6.orig/mm/rmap.c > > +++ linux-2.6/mm/rmap.c > > @@ -432,7 +432,7 @@ static int page_mkclean_one(struct page > > { > > struct mm_struct *mm = vma->vm_mm; > > unsigned long address; > > - pte_t *pte, entry; > > + pte_t *ptep; > > spinlock_t *ptl; > > int ret = 0; > > > > @@ -440,22 +440,23 @@ static int page_mkclean_one(struct page > > if (address == -EFAULT) > > goto out; > > > > - pte = page_check_address(page, mm, address, &ptl); > > - if (!pte) > > + ptep = page_check_address(page, mm, address, &ptl); > > + if (!ptep) > > goto out; > > > > - if (!pte_dirty(*pte) && !pte_write(*pte)) > > - goto unlock; > > - > > - entry = ptep_get_and_clear(mm, address, pte); > > - entry = pte_mkclean(entry); > > - entry = pte_wrprotect(entry); > > - ptep_establish(vma, address, pte, entry); > > - lazy_mmu_prot_update(entry); > > - ret = 1; > > + while (pte_dirty(*ptep) || pte_write(*ptep)) { > > + pte_t entry = ptep_get_and_clear(mm, address, ptep); > > + flush_cache_page(vma, address, pte_pfn(entry)); > > + flush_tlb_page(vma, address); > > + (void)page_test_and_clear_dirty(page); /* do the s390 thing */ > > + entry = pte_wrprotect(entry); > > + entry = pte_mkclean(entry); > > + set_pte_at(vma, address, ptep, entry); > > + lazy_mmu_prot_update(entry); > > + ret = 1; > > + } > > > Having the assignment of "ret = 1;" inside the loop seems a little > pointless. Perhaps gcc can optimize it, but still, that assignment > really only needs to happen once outside the loop. Sure, but I was hoping gcc was smart enough. Placing it outside the loop would require an extra if stmt. Also the chance this loop will actually be traversed more than once is _very_ small. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/