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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id i7-v6sm29336566wrb.30.2018.10.18.22.58.45 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 18 Oct 2018 22:58:46 -0700 (PDT) Date: Fri, 19 Oct 2018 07:58:44 +0200 From: Ingo Molnar To: "Eric W. Biederman" Cc: tip-bot for Dave Hansen , linux-tip-commits@vger.kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, hpa@zytor.com, jannh@google.com, sean.j.christopherson@intel.com, peterz@infradead.org, luto@kernel.org Subject: Re: [tip:x86/mm] x86/mm: Break out user address space handling Message-ID: <20181019055844.GA50013@gmail.com> References: <20180928160223.9C4F6440@viggo.jf.intel.com> <87k1mjpxwi.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k1mjpxwi.fsf@xmission.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Eric W. Biederman wrote: > tip-bot for Dave Hansen writes: > > > Commit-ID: aa37c51b9421d66f7931c5fdcb9ce80c450974be > > Gitweb: https://git.kernel.org/tip/aa37c51b9421d66f7931c5fdcb9ce80c450974be > > Author: Dave Hansen > > AuthorDate: Fri, 28 Sep 2018 09:02:23 -0700 > > Committer: Peter Zijlstra > > CommitDate: Tue, 9 Oct 2018 16:51:15 +0200 > > > > x86/mm: Break out user address space handling > > > > The last patch broke out kernel address space handing into its own > > helper. Now, do the same for user address space handling. > > > > Cc: x86@kernel.org > > Cc: Jann Horn > > Cc: Sean Christopherson > > Cc: Thomas Gleixner > > Cc: Andy Lutomirski > > Signed-off-by: Dave Hansen > > Signed-off-by: Peter Zijlstra (Intel) > > Link: http://lkml.kernel.org/r/20180928160223.9C4F6440@viggo.jf.intel.com > > --- > > arch/x86/mm/fault.c | 47 ++++++++++++++++++++++++++++------------------- > > 1 file changed, 28 insertions(+), 19 deletions(-) > > > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > > index c7e32f453852..0d1f5d39fc63 100644 > > --- a/arch/x86/mm/fault.c > > +++ b/arch/x86/mm/fault.c > > @@ -966,6 +966,7 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code, > > __bad_area(regs, error_code, address, vma, SEGV_ACCERR); > > } > > > > +/* Handle faults in the kernel portion of the address space */ > ^^^^^^ > I believe you mean the __user__ portion of the address space. > Given that the call chain is: > > do_user_addr_fault > handle_mm_fault > do_sigbus It's both: /* Handle faults in the kernel portion of the address space */ static void do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, u32 *pkey, unsigned int fault) { struct task_struct *tsk = current; int code = BUS_ADRERR; /* Kernel mode? Handle exceptions or die: */ if (!(error_code & X86_PF_USER)) { no_context(regs, error_code, address, SIGBUS, BUS_ADRERR); return; } /* User-space => ok to do another page fault: */ if (is_prefetch(regs, error_code, address)) return; tsk->thread.cr2 = address; tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_PF; Note the X86_PF_USER check: that's what determines whether the fault was for user or system mappings. I agree that the comment is misleading and should be clarified. Thanks, Ingo