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Tsirkin" , Stefano Garzarella , eperezma , Paolo Bonzini , ming.lei@redhat.com, Petr Mladek , John Ogness , Peter Zijlstra , Jens Axboe Subject: Re: Lockdep warnings on kexec (virtio_blk, hrtimers) In-Reply-To: References: <1f631458c180c975c238d4d33d333f9fa9a4d2a3.camel@infradead.org> <20241211124240.GA310916@fedora> <7717fe2ac0ce5f0a2c43fdab8b11f4483d54a2a4.camel@infradead.org> <87ldwl9g93.ffs@tglx> <10f5d22150b548ec271e0a847ba2eb91139e6f61.camel@infradead.org> <87a5d0aibc.ffs@tglx> <874j38a16p.ffs@tglx> <9c4b189656a0a773227a11568171903989130bb7.camel@infradead.org> Date: Fri, 13 Dec 2024 11:42:59 +0100 Message-ID: <871pybamoc.ffs@tglx> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Fri, Dec 13 2024 at 09:43, David Woodhouse wrote: > On Fri, 2024-12-13 at 09:31 +0000, David Woodhouse wrote: >> >> (gdb) p sysrq_handle_showstate('t') >> >> That didn't work. Maybe if I'd actually had no_console_suspend on this >> boot. Will try again. > > With your fix I get the same thing (both CPUs in idle thread). And with > no_console_suspend on the command line, 'p sysrq_handle_showstate('t')' > does work... > > [ 113.462898] task:loadret state:D stack:0 pid:707 tgid:707 ppid:531 flags:0x00004002 > [ 113.463615] Call Trace: > [ 113.463841] > [ 113.464029] __schedule+0x502/0x1a10 > [ 113.464961] schedule+0x3a/0x140 > [ 113.465234] schedule_timeout+0xcc/0x110 > [ 113.465580] __wait_for_common+0x91/0x1c0 > [ 113.466304] cpuhp_kick_ap_work+0x13e/0x390 > [ 113.466657] _cpu_down+0xd4/0x370 > [ 113.466936] freeze_secondary_cpus.cold+0x3f/0xd4 > [ 113.467326] kernel_kexec+0xa2/0x1a0 That's the control thread on CPU0. The hotplug thread on CPU1 is stuck here: task:cpuhp/1 state:D stack:0 pid:24 tgid:24 ppid:2 flags:0x00004000 Call Trace: __schedule+0x51f/0x1a80 schedule+0x3a/0x140 schedule_timeout+0x90/0x110 msleep+0x2b/0x40 blk_mq_hctx_notify_offline+0x160/0x3a0 cpuhp_invoke_callback+0x2a8/0x6c0 cpuhp_thread_fun+0x1ed/0x270 smpboot_thread_fn+0xda/0x1d0 So something with those blk_mq fixes went sideways. Thanks, tglx