From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id DE7BC2096AEFC for ; Wed, 9 May 2018 03:46:37 -0700 (PDT) Date: Wed, 9 May 2018 12:46:35 +0200 From: Jan Kara Subject: Re: [PATCH v9 5/9] mm: fix __gup_device_huge vs unmap Message-ID: <20180509104635.57upe2fri7abqu7p@quack2.suse.cz> References: <152461278149.17530.2867511144531572045.stgit@dwillia2-desk3.amr.corp.intel.com> <152461280975.17530.2817946409563456285.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <152461280975.17530.2817946409563456285.stgit@dwillia2-desk3.amr.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams Cc: Jan Kara , linux-nvdimm@lists.01.org, david@fromorbit.com, stable@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, hch@lst.de List-ID: On Tue 24-04-18 16:33:29, Dan Williams wrote: > get_user_pages_fast() for device pages is missing the typical validation > that all page references have been taken while the mapping was valid. > Without this validation truncate operations can not reliably coordinate > against new page reference events like O_DIRECT. > > Cc: > Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings") > Reported-by: Jan Kara > Signed-off-by: Dan Williams The patch looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > mm/gup.c | 36 ++++++++++++++++++++++++++---------- > 1 file changed, 26 insertions(+), 10 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 76af4cfeaf68..84dd2063ca3d 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1456,32 +1456,48 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr, > return 1; > } > > -static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr, > +static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > unsigned long end, struct page **pages, int *nr) > { > unsigned long fault_pfn; > + int nr_start = *nr; > + > + fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > + if (!__gup_device_huge(fault_pfn, addr, end, pages, nr)) > + return 0; > > - fault_pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > - return __gup_device_huge(fault_pfn, addr, end, pages, nr); > + if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) { > + undo_dev_pagemap(nr, nr_start, pages); > + return 0; > + } > + return 1; > } > > -static int __gup_device_huge_pud(pud_t pud, unsigned long addr, > +static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > unsigned long end, struct page **pages, int *nr) > { > unsigned long fault_pfn; > + int nr_start = *nr; > + > + fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > + if (!__gup_device_huge(fault_pfn, addr, end, pages, nr)) > + return 0; > > - fault_pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > - return __gup_device_huge(fault_pfn, addr, end, pages, nr); > + if (unlikely(pud_val(orig) != pud_val(*pudp))) { > + undo_dev_pagemap(nr, nr_start, pages); > + return 0; > + } > + return 1; > } > #else > -static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr, > +static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > unsigned long end, struct page **pages, int *nr) > { > BUILD_BUG(); > return 0; > } > > -static int __gup_device_huge_pud(pud_t pud, unsigned long addr, > +static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr, > unsigned long end, struct page **pages, int *nr) > { > BUILD_BUG(); > @@ -1499,7 +1515,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, > return 0; > > if (pmd_devmap(orig)) > - return __gup_device_huge_pmd(orig, addr, end, pages, nr); > + return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr); > > refs = 0; > page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > @@ -1537,7 +1553,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr, > return 0; > > if (pud_devmap(orig)) > - return __gup_device_huge_pud(orig, addr, end, pages, nr); > + return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr); > > refs = 0; > page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); > -- Jan Kara SUSE Labs, CR _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm