Messages in this thread | | | From | <> | Subject | Re: [PATCH -next] arch_topology: Fix cache attributes detection in the CPU hotplug path | Date | Mon, 18 Jul 2022 17:57:33 +0000 |
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On 18/07/2022 18:41, Guenter Roeck wrote: > On Wed, Jul 13, 2022 at 02:33:44PM +0100, Sudeep Holla wrote: >> init_cpu_topology() is called only once at the boot and all the cache >> attributes are detected early for all the possible CPUs. However when >> the CPUs are hotplugged out, the cacheinfo gets removed. While the >> attributes are added back when the CPUs are hotplugged back in as part >> of CPU hotplug state machine, it ends up called quite late after the >> update_siblings_masks() are called in the secondary_start_kernel() >> resulting in wrong llc_sibling_masks. >> >> Move the call to detect_cache_attributes() inside update_siblings_masks() >> to ensure the cacheinfo is updated before the LLC sibling masks are >> updated. This will fix the incorrect LLC sibling masks generated when >> the CPUs are hotplugged out and hotplugged back in again. >> >> Reported-by: Ionela Voinescu <ionela.voinescu@arm.com> >> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> >> --- >> drivers/base/arch_topology.c | 16 ++++++---------- >> 1 file changed, 6 insertions(+), 10 deletions(-) >> >> Hi Conor, >> >> Ionela reported an issue with the CPU hotplug and as a fix I need to >> move the call to detect_cache_attributes() which I had thought to keep >> it there from first but for no reason had moved it to init_cpu_topology(). >> >> Wonder if this fixes the -ENOMEM on RISC-V as this one is called on the >> cpu in the secondary CPUs init path while init_cpu_topology executed >> detect_cache_attributes() for all possible CPUs much earlier. I think >> this might help as the percpu memory might be initialised in this case. >> >> Anyways give this a try, also test the CPU hotplug and check if nothing >> is broken on RISC-V. We noticed this bug only on one platform while >> > > arm64, with next-20220718: > > ... > [ 0.823405] Detected PIPT I-cache on CPU1 > [ 0.824456] BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:164 > [ 0.824550] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/1 > [ 0.824600] preempt_count: 1, expected: 0 > [ 0.824633] RCU nest depth: 0, expected: 0 > [ 0.824899] no locks held by swapper/1/0. > [ 0.825035] irq event stamp: 0 > [ 0.825072] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.826017] hardirqs last disabled at (0): [<ffff800008158870>] copy_process+0x5e0/0x18e4 > [ 0.826123] softirqs last enabled at (0): [<ffff800008158870>] copy_process+0x5e0/0x18e4 > [ 0.826191] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.826764] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.19.0-rc7-next-20220718 #1 > [ 0.827397] Call trace: > [ 0.827456] dump_backtrace.part.0+0xd4/0xe0 > [ 0.827574] show_stack+0x18/0x50 > [ 0.827625] dump_stack_lvl+0x9c/0xd8 > [ 0.827678] dump_stack+0x18/0x34 > [ 0.827722] __might_resched+0x178/0x220 > [ 0.827778] __might_sleep+0x48/0x80 > [ 0.827833] down_timeout+0x2c/0xa0 > [ 0.827896] acpi_os_wait_semaphore+0x68/0x9c > [ 0.827952] acpi_ut_acquire_mutex+0x4c/0xb8 > [ 0.828008] acpi_get_table+0x38/0xbc > [ 0.828059] acpi_find_last_cache_level+0x44/0x130 > [ 0.828112] init_cache_level+0xb8/0xcc > [ 0.828165] detect_cache_attributes+0x240/0x580 > [ 0.828217] update_siblings_masks+0x28/0x270 > [ 0.828270] store_cpu_topology+0x64/0x74 > [ 0.828326] secondary_start_kernel+0xd0/0x150 > [ 0.828386] __secondary_switched+0xb0/0xb4 > > I know the problem has already been reported, but I think the backtrace > above is slightly different.
Aye, I got a different BT on RISC-V + DT - but that should be fixed in next-20220718. This is a different problem unfortunately.
Thanks, Conor.
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