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Donenfeld" , "Guenter Roeck" Subject: Re: [GIT PULL] Please pull powerpc/linux.git powerpc-6.1-1 tag From: "Nicholas Piggin" X-Mailer: aerc 0.11.0 References: <87edvhntv0.fsf@mpe.ellerman.id.au> <20221012141827.GA2405914@roeck-us.net> <20221012164452.GA2990467@roeck-us.net> <20221012174826.GB2995920@roeck-us.net> In-Reply-To: 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: david@redhat.com, linux-kernel@vger.kernel.org, wsa+renesas@sang-engineering.com, nicholas@linux.ibm.com, windhl@126.com, cuigaosheng1@huawei.com, mikey@neuling.org, paul@paul-moore.com, haren@linux.ibm.com, joel@jms.id.au, lukas.bulwahn@gmail.com, nathanl@linux.ibm.com, ajd@linux.ibm.com, ye.xingchen@zte.com.cn, nathan@kernel.org, rmclure@linux.ibm.com, hbathini@linux.ibm.com, atrajeev@linux.vnet.ibm.com, yuanjilin@cdjrlc.com, pali@kernel.org, farosas@linux.ibm.com, geoff@infradead.org, Linus Torvalds , gustavoars@kernel.org, lihuafei1@huawei.com, aneesh.kumar@linux.ibm.com, zhengyongjun3@huawei.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu Oct 13, 2022 at 4:37 AM AEST, Jason A. Donenfeld wrote: > On Wed, Oct 12, 2022 at 10:48:26AM -0700, Guenter Roeck wrote: > > > I've also managed to not hit this bug a few times. When it triggers, > > > after "kprobes: kprobe jump-optimization is enabled. All kprobes are > > > optimized if possible.", there's a long hang - tens seconds before it > > > continues. When it doesn't trigger, there's no hang at that point in = the > > > boot process. > > >=20 > >=20 > > That probably explains why my attempts to bisect the problem were > > unsuccessful. > > So I just did this: > > diff --git a/drivers/char/random.c b/drivers/char/random.c > index 2fe28eeb2f38..2d70bc09db7e 100644 > --- a/drivers/char/random.c > +++ b/drivers/char/random.c > @@ -1212,6 +1212,7 @@ static void __cold try_to_generate_entropy(void) > struct entropy_timer_state stack; > unsigned int i, num_different =3D 0; > unsigned long last =3D random_get_entropy(); > + return; > > for (i =3D 0; i < NUM_TRIAL_SAMPLES - 1; ++i) { > stack.entropy =3D random_get_entropy(); > > And then ran it, and now we get the lockup from the idle process: Yep that rules out the random code. And really if it was calling schedule() it shouldn't be getting a softlockup anyway. Thanks, Nick