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[2001:8b0:10b:1231::1]) by mx.google.com with ESMTPS id x6si5536853wmc.107.2019.04.12.11.19.38 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 12 Apr 2019 11:19:38 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) client-ip=2001:8b0:10b:1231::1; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=SyI3VINw; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=KpJsBc8SapSFzeXew9+sq3mf1ByhcdS4G0yhgcMADv4=; b=SyI3VINwNFgLzvaWksaXcp57z OrBAd86qQeWRtn4Gdt9uziZE4aq7ToC5Tnfpu4N3NXuW6PMlNq3fWO4f03wLNaSMRjUwBvJEnCCfg CtUaHXVvyjRBs+NvtqLt1apQ51+dZYEAXA8xEAyizv4v9KVsHjaekuqY9U+spyCcS1UwGB8BbzMGR APuailpptjRAjn8LmBLLairGX37lhLp1cNkd7D/0MaWUqLYPRH1Keb9QJ/dr1aaC+nqgNrVrbWmfD +lWdvRcIjVM/Oten7rbKgGYRENjKF8J0TtOJ9enf+7e2vrpvkq8WrFIhCbPAZnHeHca+meF6XC9JO +uq7yLbsw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hF0lv-0003Q9-NP; Fri, 12 Apr 2019 18:19:31 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 73C1529B20C3F; Fri, 12 Apr 2019 20:19:30 +0200 (CEST) Date: Fri, 12 Apr 2019 20:19:30 +0200 From: Peter Zijlstra To: Nadav Amit Cc: kernel test robot , LKP , Linux List Kernel Mailing , Linux-MM , linux-arch , Ingo Molnar , Thomas Gleixner , Will Deacon , Andy Lutomirski , Linus Torvalds , Dave Hansen Subject: Re: 1808d65b55 ("asm-generic/tlb: Remove arch_tlb*_mmu()"): BUG: KASAN: stack-out-of-bounds in __change_page_attr_set_clr Message-ID: <20190412181930.GD12232@hirez.programming.kicks-ass.net> 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> <20190412111756.GO14281@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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 03:11:22PM +0000, Nadav Amit wrote: > > On Apr 12, 2019, at 4:17 AM, Peter Zijlstra wrote: > > To clarify, 'that' is Nadav's patch: > > > > 515ab7c41306 ("x86/mm: Align TLB invalidation info") > > > > which turns out to be the real problem. > > Sorry for that. I still think it should be aligned, especially with all the > effort the Intel puts around to avoid bus-locking on unaligned atomic > operations. No atomics anywhere in sight, so that's not a concern. > So the right solution seems to me as putting this data structure off stack. > It would prevent flush_tlb_mm_range() from being reentrant, so we can keep a > few entries for this matter and atomically increase the entry number every > time we enter flush_tlb_mm_range(). > > But my question is - should flush_tlb_mm_range() be reentrant, or can we > assume no TLB shootdowns are initiated in interrupt handlers and #MC > handlers? There _should_ not be, but then don't look at those XPFO patches that were posted (they're broken anyway).