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[2a0a:51c0:0:12e:550::1]) by mx.google.com with ESMTPS id y16si20482234wmc.177.2019.07.17.14.43.53 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Wed, 17 Jul 2019 14:43:53 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a0a:51c0:0:12e:550::1 as permitted sender) client-ip=2a0a:51c0:0:12e:550::1; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a0a:51c0:0:12e:550::1 as permitted sender) smtp.mailfrom=tglx@linutronix.de Received: from pd9ef1cb8.dip0.t-ipconnect.de ([217.239.28.184] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1hnriC-0005hz-EP; Wed, 17 Jul 2019 23:43:44 +0200 Date: Wed, 17 Jul 2019 23:43:43 +0200 (CEST) From: Thomas Gleixner To: Joerg Roedel cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Ingo Molnar , Borislav Petkov , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joerg Roedel Subject: Re: [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_one() In-Reply-To: <20190717071439.14261-3-joro@8bytes.org> Message-ID: References: <20190717071439.14261-1-joro@8bytes.org> <20190717071439.14261-3-joro@8bytes.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 17 Jul 2019, Joerg Roedel wrote: > From: Joerg Roedel > > With huge-page ioremap areas the unmappings also need to be > synced between all page-tables. Otherwise it can cause data > corruption when a region is unmapped and later re-used. > > Make the vmalloc_sync_one() function ready to sync > unmappings. > > Fixes: 5d72b4fba40ef ('x86, mm: support huge I/O mapping capability I/F') > Signed-off-by: Joerg Roedel > --- > arch/x86/mm/fault.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > index 4a4049f6d458..d71e167662c3 100644 > --- a/arch/x86/mm/fault.c > +++ b/arch/x86/mm/fault.c > @@ -194,11 +194,12 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) > > pmd = pmd_offset(pud, address); > pmd_k = pmd_offset(pud_k, address); > - if (!pmd_present(*pmd_k)) > - return NULL; > > - if (!pmd_present(*pmd)) > + if (pmd_present(*pmd) ^ pmd_present(*pmd_k)) > set_pmd(pmd, *pmd_k); > + > + if (!pmd_present(*pmd_k)) > + return NULL; > else > BUG_ON(pmd_pfn(*pmd) != pmd_pfn(*pmd_k)); So in case of unmap, this updates only the first entry in the pgd_list because vmalloc_sync_all() will break out of the iteration over pgd_list when NULL is returned from vmalloc_sync_one(). I'm surely missing something, but how is that supposed to sync _all_ page tables on unmap as the changelog claims? Thanks, tglx