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Darwish" Subject: Re: [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables Message-ID: <20200623163730.GA4800@hirez.programming.kicks-ass.net> References: <20200623083645.277342609@infradead.org> <20200623083721.512673481@infradead.org> <20200623150031.GA2986783@debian-buster-darwi.lab.linutronix.de> <20200623152450.GM4817@hirez.programming.kicks-ass.net> <20200623161320.GA2996373@debian-buster-darwi.lab.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200623161320.GA2996373@debian-buster-darwi.lab.linutronix.de> 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: linux-s390@vger.kernel.org, elver@google.com, linuxppc-dev@lists.ozlabs.org, bigeasy@linutronix.de, x86@kernel.org, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, davem@davemloft.net, sparclinux@vger.kernel.org, linux@armlinux.org.uk, tglx@linutronix.de, will@kernel.org, mingo@kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Jun 23, 2020 at 06:13:21PM +0200, Ahmed S. Darwish wrote: > Well, freshly merged code is using it. For example, KCSAN: > > => f1bc96210c6a ("kcsan: Make KCSAN compatible with lockdep") > => kernel/kcsan/report.c: > > void kcsan_report(...) > { > ... > /* > * With TRACE_IRQFLAGS, lockdep's IRQ trace state becomes corrupted if > * we do not turn off lockdep here; this could happen due to recursion > * into lockdep via KCSAN if we detect a race in utilities used by > * lockdep. > */ > lockdep_off(); > ... > } Marco, do you remember what exactly happened there? Because I'm about to wreck that. That is, I'm going to make TRACE_IRQFLAGS ignore lockdep_off().