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[209.85.208.172]) by smtp.gmail.com with ESMTPSA id u11sm8367289ljh.80.2019.04.12.08.32.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Apr 2019 08:32:55 -0700 (PDT) Received: by mail-lj1-f172.google.com with SMTP id l7so9251975ljg.6 for ; Fri, 12 Apr 2019 08:32:55 -0700 (PDT) X-Received: by 2002:a2e:9a91:: with SMTP id p17mr30639609lji.127.1555083174727; Fri, 12 Apr 2019 08:32:54 -0700 (PDT) MIME-Version: 1.0 References: <5cae03c4.iIPk2cWlfmzP0Zgy%lkp@intel.com> <20190411193906.GA12232@hirez.programming.kicks-ass.net> <20190411195424.GL14281@hirez.programming.kicks-ass.net> <20190411211348.GA8451@worktop.programming.kicks-ass.net> <20190412105633.GM14281@hirez.programming.kicks-ass.net> In-Reply-To: <20190412105633.GM14281@hirez.programming.kicks-ass.net> From: Linus Torvalds Date: Fri, 12 Apr 2019 08:32:38 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: 1808d65b55 ("asm-generic/tlb: Remove arch_tlb*_mmu()"): BUG: KASAN: stack-out-of-bounds in __change_page_attr_set_clr To: Peter Zijlstra Cc: kernel test robot , LKP , Linux List Kernel Mailing , Linux-MM , linux-arch , Ingo Molnar , Thomas Gleixner , Will Deacon , Andy Lutomirski , Nadav Amit , Linus Torvalds Content-Type: text/plain; charset="UTF-8" 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 Fri, Apr 12, 2019 at 3:56 AM Peter Zijlstra wrote: > > --- a/arch/x86/mm/tlb.c > +++ b/arch/x86/mm/tlb.c > @@ -728,7 +728,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, > { > int cpu; > > - struct flush_tlb_info info __aligned(SMP_CACHE_BYTES) = { > + struct flush_tlb_info info = { > .mm = mm, > .stride_shift = stride_shift, > .freed_tables = freed_tables, > Ack. We should never have stack alignment bigger than 16 bytes. And preferably not even that. Trying to align stack at a cacheline boundary is wrong - if you *really* need things to be that aligned, do something else (regular kmalloc, percpu temp area, static allocation - whatever). Linus