From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A073E29AD for ; Fri, 18 Nov 2022 10:33:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=ery4e7DXynGUHcFDdPwXSq/cHJt8hNQ6mXrrfbI6xLk=; b=EIGeQOPHkYWExKKZj8puEdHFeG 3uF7oA7oIK4hx+OZebNmAvZGuL3ecRuBR9gvsGIjdiUJ4yC4uURrDvGR5k+ITrfnIN4oHVlgyPR5I D9nZ0xZyxdjb+JrMOYqCiin876QRJQN+hx3l3Kdd7sf95yKGzo+idh+uVVmFnzn/hzMNR5/urvAlT dI0QMG5YBg+sT7jGX8Y/UcIR9S5TIJaVeN4N+oByK2TayIcf1aO/CQna0NxS+JOnz/bXR8zP7S7nx rwBIlkL8NIzGToNjO6PMoZIv2z3mfsN649W0Rk7hDNd6kOEMR2AtDQYZ3UWuq2cV9hf8p6LN//MVv nrWWxBEQ==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ovyg3-001x27-EE; Fri, 18 Nov 2022 10:32:55 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6F817300462; Fri, 18 Nov 2022 11:32:54 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 527C520C9821C; Fri, 18 Nov 2022 11:32:54 +0100 (CET) Date: Fri, 18 Nov 2022 11:32:54 +0100 From: Peter Zijlstra To: Dave Hansen Cc: Marco Elver , Naresh Kamboju , kasan-dev , X86 ML , open list , linux-mm , regressions@lists.linux.dev, lkft-triage@lists.linaro.org, Andrew Morton , Alexander Potapenko Subject: Re: WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/kfence.h:46 kfence_protect Message-ID: References: <4208866d-338f-4781-7ff9-023f016c5b07@intel.com> <41ac24c4-6c95-d946-2679-c1be2cb20536@intel.com> Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41ac24c4-6c95-d946-2679-c1be2cb20536@intel.com> On Thu, Nov 17, 2022 at 03:54:21PM -0800, Dave Hansen wrote: > On 11/17/22 15:23, Marco Elver wrote: > > Yes - it's the 'level != PG_LEVEL_4K'. > > That plus the bisect made it pretty easy to find, thanks for the effort! > > Could you double-check that the attached patch fixes it? It seemed to > for me. > > The issue was that the new "No changes, easy!" check in the suspect > commit didn't check the cpa->force_split option. It didn't split down > to 4k and then all hell broke loose. > > Oh, and I totally misread the kfence ability to tolerate partial TLB > flushes. Sorry for the noise there! > diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c > index 220361ceb997..9b4e2ad957f6 100644 > --- a/arch/x86/mm/pat/set_memory.c > +++ b/arch/x86/mm/pat/set_memory.c > @@ -1727,7 +1727,8 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int primary) > /* > * No changes, easy! > */ > - if (!(pgprot_val(cpa->mask_set) | pgprot_val(cpa->mask_clr))) > + if (!(pgprot_val(cpa->mask_set) | pgprot_val(cpa->mask_clr)) > + && !cpa->force_split) (operators go at the end of the previous line) > return ret; > > while (rempages) { Urgh.. sorry about that.