diff options
| author | Pierre Gondois <pierre.gondois@arm.com> | 2023-01-04 19:30:29 +0100 |
|---|---|---|
| committer | Sudeep Holla <sudeep.holla@arm.com> | 2023-01-18 09:58:40 +0000 |
| commit | 5944ce092b97caed5d86d961e963b883b5c44ee2 (patch) | |
| tree | c2cb319504a77324b00f5a4b9c3008d05f05edb8 /include/linux/cacheinfo.h | |
| parent | bd500361a937c03a3da57178287ce543c8f3681b (diff) | |
arch_topology: Build cacheinfo from primary CPU
commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection
in the CPU hotplug path")
adds a call to detect_cache_attributes() to populate the cacheinfo
before updating the siblings mask. detect_cache_attributes() allocates
memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT
kernels, on secondary CPUs, this triggers a:
'BUG: sleeping function called from invalid context' [1]
as the code is executed with preemption and interrupts disabled.
The primary CPU was previously storing the cache information using
the now removed (struct cpu_topology).llc_id:
commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from
the CPU topology")
allocate_cache_info() tries to build the cacheinfo from the primary
CPU prior secondary CPUs boot, if the DT/ACPI description
contains cache information.
If allocate_cache_info() fails, then fallback to the current state
for the cacheinfo allocation. [1] will be triggered in such case.
When unplugging a CPU, the cacheinfo memory cannot be freed. If it
was, then the memory would be allocated early by the re-plugged
CPU and would trigger [1].
Note that populate_cache_leaves() might be called multiple times
due to populate_leaves being moved up. This is required since
detect_cache_attributes() might be called with per_cpu_cacheinfo(cpu)
being allocated but not populated.
[1]:
| BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
| in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111
| preempt_count: 1, expected: 0
| RCU nest depth: 1, expected: 1
| 3 locks held by swapper/111/0:
| #0: (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8
| #1: (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0
| #2: (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80
| irq event stamp: 0
| hardirqs last enabled at (0): 0x0
| hardirqs last disabled at (0): copy_process+0x5dc/0x1ab8
| softirqs last enabled at (0): copy_process+0x5dc/0x1ab8
| softirqs last disabled at (0): 0x0
| Preemption disabled at:
| migrate_enable+0x30/0x130
| CPU: 111 PID: 0 Comm: swapper/111 Tainted: G W 6.0.0-rc4-rt6-[...]
| Call trace:
| __kmalloc+0xbc/0x1e8
| detect_cache_attributes+0x2d4/0x5f0
| update_siblings_masks+0x30/0x368
| store_cpu_topology+0x78/0xb8
| secondary_start_kernel+0xd0/0x198
| __secondary_switched+0xb0/0xb4
Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20230104183033.755668-7-pierre.gondois@arm.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Diffstat (limited to 'include/linux/cacheinfo.h')
| -rw-r--r-- | include/linux/cacheinfo.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h index 00d8e7f9d1c6..dfef57077cd0 100644 --- a/include/linux/cacheinfo.h +++ b/include/linux/cacheinfo.h @@ -85,6 +85,7 @@ int populate_cache_leaves(unsigned int cpu); int cache_setup_acpi(unsigned int cpu); bool last_level_cache_is_valid(unsigned int cpu); bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y); +int fetch_cache_info(unsigned int cpu); int detect_cache_attributes(unsigned int cpu); #ifndef CONFIG_ACPI_PPTT /* |