From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4C1CC433DF for ; Wed, 17 Jun 2020 11:10:38 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 613B22078D for ; Wed, 17 Jun 2020 11:10:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="uEnXH1vp" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 613B22078D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 49n2Rb28bczDqw4 for ; Wed, 17 Jun 2020 21:10:35 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=willy@infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=bombadil.20170209 header.b=uEnXH1vp; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 49n2PN1WD4zDqkg for ; Wed, 17 Jun 2020 21:08:39 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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; bh=6UMFO2TmbdpnJT0c5EXP2Aydp2MaQ5RYJc+GA8ZrxVg=; b=uEnXH1vpZaG2U8FFM/pYkfHc5Y SeAjiiS0wb4uxVIyAse/Mlkd6U3qaJ4r4kEh9T7lE+/o5L5t1dNjJ28G/NIqVe0DWG/fV4/lQHo1o QDwGZP0qomelniIocS0ybLZQjvlRxX/INLpmjUp5+LL4fh2HQo9F6qYCqhyg1imU2AHxFgkQk0jvm 8nOqGDFYb7CZcfryOG0jsO4VWYAKfvslQU5aBRvXZEAb7odmsPQzoqooHS6qL3UZV2AdZFQmkWhak uKTLzMfmXR1ZbqokaLQoFEtbowD5zP+hhe/qVdQ+y0/QB4rOvsOqTW0JOhm+R3UUkEQZTtPszFNR9 vDBLz4ZQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jlVvY-0007BQ-88; Wed, 17 Jun 2020 11:08:20 +0000 Date: Wed, 17 Jun 2020 04:08:20 -0700 From: Matthew Wilcox To: Michal Hocko Subject: Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() Message-ID: <20200617110820.GG8681@bombadil.infradead.org> References: <20200616015718.7812-1-longman@redhat.com> <20200616230130.GJ27795@twin.jikos.cz> <20200617003711.GD8681@bombadil.infradead.org> <20200617071212.GJ9499@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200617071212.GJ9499@dhcp22.suse.cz> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Jason A . Donenfeld" , linux-btrfs@vger.kernel.org, Jarkko Sakkinen , dsterba@suse.cz, David Howells , linux-mm@kvack.org, linux-sctp@vger.kernel.org, keyrings@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org, linux-scsi@vger.kernel.org, James Morris , kasan-dev@googlegroups.com, linux-wpan@vger.kernel.org, David Rientjes , Waiman Long , Dan Carpenter , "Serge E. Hallyn" , linux-pm@vger.kernel.org, ecryptfs@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-amlogic@lists.infradead.org, virtualization@lists.linux-foundation.org, linux-integrity@vger.kernel.org, linux-nfs@vger.kernel.org, Linus Torvalds , linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org, linux-security-module@vger.kernel.org, target-devel@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-crypto@vger.kernel.org, Johannes Weiner , Joe Perches , Andrew Morton , linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, wireguard@lists.zx2c4.com, linux-ppp@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jun 17, 2020 at 09:12:12AM +0200, Michal Hocko wrote: > On Tue 16-06-20 17:37:11, Matthew Wilcox wrote: > > Not just performance critical, but correctness critical. Since kvfree() > > may allocate from the vmalloc allocator, I really think that kvfree() > > should assert that it's !in_atomic(). Otherwise we can get into trouble > > if we end up calling vfree() and have to take the mutex. > > FWIW __vfree already checks for atomic context and put the work into a > deferred context. So this should be safe. It should be used as a last > resort, though. Actually, it only checks for in_interrupt(). If you call vfree() under a spinlock, you're in trouble. in_atomic() only knows if we hold a spinlock for CONFIG_PREEMPT, so it's not safe to check for in_atomic() in __vfree(). So we need the warning in order that preempt people can tell those without that there is a bug here.