From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Date: Wed, 17 Jun 2020 12:23:21 +0000 Subject: Re: [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() Message-Id: <20200617122321.GJ8681@bombadil.infradead.org> List-Id: References: <20200616015718.7812-1-longman@redhat.com> <20200616230130.GJ27795@twin.jikos.cz> <20200617003711.GD8681@bombadil.infradead.org> <20200617071212.GJ9499@dhcp22.suse.cz> <20200617110820.GG8681@bombadil.infradead.org> <20200617113157.GM9499@dhcp22.suse.cz> In-Reply-To: <20200617113157.GM9499@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko 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 , 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 On Wed, Jun 17, 2020 at 01:31:57PM +0200, Michal Hocko wrote: > On Wed 17-06-20 04:08:20, Matthew Wilcox wrote: > > 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. > > ... Unless I am missing something in_interrupt depends on preempt_count() as > well so neither of the two is reliable without PREEMPT_COUNT configured. preempt_count() always tracks whether we're in interrupt context, regardless of CONFIG_PREEMPT. The difference is that CONFIG_PREEMPT will track spinlock acquisitions as well.