| Message ID | 20221121171217.3581004-6-pierre.gondois@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arch_topology: Build cacheinfo from primary CPU | expand |
On Mon, Nov 21, 2022 at 06:12:13PM +0100, Pierre Gondois wrote: > 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]: > [ 7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 > [ 7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111 > [ 7.560796] preempt_count: 1, expected: 0 > [ 7.560797] RCU nest depth: 1, expected: 1 > [ 7.560799] 3 locks held by swapper/111/0: > [ 7.560800] #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8 > [ 7.560811] #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0 > [ 7.560820] #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80 > [ 7.560824] irq event stamp: 0 > [ 7.560825] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 7.560827] hardirqs last disabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8 > [ 7.560830] softirqs last enabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8 > [ 7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 7.560834] Preemption disabled at: > [ 7.560835] [<ffffc5f8e9fd3c28>] migrate_enable+0x30/0x130 > [ 7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G W 6.0.0-rc4-rt6-[...] > [ 7.560841] Call trace: > [...] > [ 7.560870] __kmalloc+0xbc/0x1e8 > [ 7.560873] detect_cache_attributes+0x2d4/0x5f0 > [ 7.560876] update_siblings_masks+0x30/0x368 > [ 7.560880] store_cpu_topology+0x78/0xb8 > [ 7.560883] secondary_start_kernel+0xd0/0x198 > [ 7.560885] __secondary_switched+0xb0/0xb4 > > Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> > --- > drivers/base/arch_topology.c | 10 ++++++- > drivers/base/cacheinfo.c | 56 +++++++++++++++++++++++++++++------- > include/linux/cacheinfo.h | 1 + > 3 files changed, 55 insertions(+), 12 deletions(-) > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index e7d6e6657ffa..54be88f658a0 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -825,7 +825,7 @@ __weak int __init parse_acpi_topology(void) > #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) > void __init init_cpu_topology(void) > { > - int ret; > + int cpu, ret; > > reset_cpu_topology(); > ret = parse_acpi_topology(); > @@ -840,6 +840,14 @@ void __init init_cpu_topology(void) > reset_cpu_topology(); > return; > } > + > + for_each_possible_cpu(cpu) { > + ret = allocate_cache_info(cpu); > + if (ret) { > + pr_err("Early cacheinfo failed, ret = %d\n", ret); Is it better to be more specific in the error message or do you think error code will suffice ? Something like "Early cacheinfo allocation failed, ret = %d\n" > + break; > + } > + } > } > > void store_cpu_topology(unsigned int cpuid) > diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c > index 6f6cd120c4f1..429a55e7c5e2 100644 > --- a/drivers/base/cacheinfo.c > +++ b/drivers/base/cacheinfo.c > @@ -371,10 +371,6 @@ static void free_cache_attributes(unsigned int cpu) > return; > > cache_shared_cpu_map_remove(cpu); > - > - kfree(per_cpu_cacheinfo(cpu)); > - per_cpu_cacheinfo(cpu) = NULL; > - cache_leaves(cpu) = 0; > } > > int __weak init_cache_level(unsigned int cpu) > @@ -387,18 +383,56 @@ int __weak populate_cache_leaves(unsigned int cpu) > return -ENOENT; > } > > +int allocate_cache_info(unsigned int cpu) > +{ > + struct cpu_cacheinfo *this_cpu_ci; > + unsigned int levels, split_levels; > + int ret; > + > + if (acpi_disabled) { > + ret = init_of_cache_level(cpu); > + if (ret < 0) > + return ret; > + } else { > + ret = acpi_get_cache_info(cpu, &levels, &split_levels); > + if (ret < 0) > + return ret; > + > + this_cpu_ci = get_cpu_cacheinfo(cpu); > + this_cpu_ci->num_levels = levels; > + /* > + * This assumes that: > + * - there cannot be any split caches (data/instruction) > + * above a unified cache > + * - data/instruction caches come by pair > + */ > + this_cpu_ci->num_leaves = levels + split_levels; > + } > + if (!cache_leaves(cpu)) > + return -ENOENT; > + The above part is more fetching info than allocating. Does it make sense to rename along similar lines. > + per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu), > + sizeof(struct cacheinfo), GFP_ATOMIC); > + if (per_cpu_cacheinfo(cpu) == NULL) { > + cache_leaves(cpu) = 0; > + return -ENOMEM; > + } > + IIReadC, detect_cache_attributes also have above allocation, does it make sense to consolidate into one inline function or something ? > + return ret; > +} > + > int detect_cache_attributes(unsigned int cpu) > { > int ret; > > - /* Since early detection of the cacheinfo is allowed via this > - * function and this also gets called as CPU hotplug callbacks via > - * cacheinfo_cpu_online, the initialisation can be skipped and only > - * CPU maps can be updated as the CPU online status would be update > - * if called via cacheinfo_cpu_online path. > + /* Since early initialization/allocation of the cacheinfo is allowed > + * via allocate_cache_info() and this also gets called as CPU hotplug > + * callbacks via cacheinfo_cpu_online, the init/alloc can be skipped > + * as it will happen only once (the cacheinfo memory is never freed). > + * Just populate the cacheinfo. > */ > if (per_cpu_cacheinfo(cpu)) > - goto update_cpu_map; > + goto populate_leaves; > > if (init_cache_level(cpu) || !cache_leaves(cpu)) > return -ENOENT; > @@ -410,6 +444,7 @@ int detect_cache_attributes(unsigned int cpu) > return -ENOMEM; > } > > +populate_leaves: > /* > * populate_cache_leaves() may completely setup the cache leaves and > * shared_cpu_map or it may leave it partially setup. > @@ -418,7 +453,6 @@ int detect_cache_attributes(unsigned int cpu) > if (ret) > goto free_ci; > > -update_cpu_map: > /* > * For systems using DT for cache hierarchy, fw_token > * and shared_cpu_map will be set up here only if they are > diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h > index f992d81d211f..7d390806b788 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 allocate_cache_info(unsigned int cpu); > int detect_cache_attributes(unsigned int cpu); > #ifndef CONFIG_ACPI_PPTT > /* > -- > 2.25.1 > With above nits fixed or discussed further to retain as is, you can add Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index e7d6e6657ffa..54be88f658a0 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -825,7 +825,7 @@ __weak int __init parse_acpi_topology(void) #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) void __init init_cpu_topology(void) { - int ret; + int cpu, ret; reset_cpu_topology(); ret = parse_acpi_topology(); @@ -840,6 +840,14 @@ void __init init_cpu_topology(void) reset_cpu_topology(); return; } + + for_each_possible_cpu(cpu) { + ret = allocate_cache_info(cpu); + if (ret) { + pr_err("Early cacheinfo failed, ret = %d\n", ret); + break; + } + } } void store_cpu_topology(unsigned int cpuid) diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index 6f6cd120c4f1..429a55e7c5e2 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -371,10 +371,6 @@ static void free_cache_attributes(unsigned int cpu) return; cache_shared_cpu_map_remove(cpu); - - kfree(per_cpu_cacheinfo(cpu)); - per_cpu_cacheinfo(cpu) = NULL; - cache_leaves(cpu) = 0; } int __weak init_cache_level(unsigned int cpu) @@ -387,18 +383,56 @@ int __weak populate_cache_leaves(unsigned int cpu) return -ENOENT; } +int allocate_cache_info(unsigned int cpu) +{ + struct cpu_cacheinfo *this_cpu_ci; + unsigned int levels, split_levels; + int ret; + + if (acpi_disabled) { + ret = init_of_cache_level(cpu); + if (ret < 0) + return ret; + } else { + ret = acpi_get_cache_info(cpu, &levels, &split_levels); + if (ret < 0) + return ret; + + this_cpu_ci = get_cpu_cacheinfo(cpu); + this_cpu_ci->num_levels = levels; + /* + * This assumes that: + * - there cannot be any split caches (data/instruction) + * above a unified cache + * - data/instruction caches come by pair + */ + this_cpu_ci->num_leaves = levels + split_levels; + } + if (!cache_leaves(cpu)) + return -ENOENT; + + per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu), + sizeof(struct cacheinfo), GFP_ATOMIC); + if (per_cpu_cacheinfo(cpu) == NULL) { + cache_leaves(cpu) = 0; + return -ENOMEM; + } + + return ret; +} + int detect_cache_attributes(unsigned int cpu) { int ret; - /* Since early detection of the cacheinfo is allowed via this - * function and this also gets called as CPU hotplug callbacks via - * cacheinfo_cpu_online, the initialisation can be skipped and only - * CPU maps can be updated as the CPU online status would be update - * if called via cacheinfo_cpu_online path. + /* Since early initialization/allocation of the cacheinfo is allowed + * via allocate_cache_info() and this also gets called as CPU hotplug + * callbacks via cacheinfo_cpu_online, the init/alloc can be skipped + * as it will happen only once (the cacheinfo memory is never freed). + * Just populate the cacheinfo. */ if (per_cpu_cacheinfo(cpu)) - goto update_cpu_map; + goto populate_leaves; if (init_cache_level(cpu) || !cache_leaves(cpu)) return -ENOENT; @@ -410,6 +444,7 @@ int detect_cache_attributes(unsigned int cpu) return -ENOMEM; } +populate_leaves: /* * populate_cache_leaves() may completely setup the cache leaves and * shared_cpu_map or it may leave it partially setup. @@ -418,7 +453,6 @@ int detect_cache_attributes(unsigned int cpu) if (ret) goto free_ci; -update_cpu_map: /* * For systems using DT for cache hierarchy, fw_token * and shared_cpu_map will be set up here only if they are diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h index f992d81d211f..7d390806b788 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 allocate_cache_info(unsigned int cpu); int detect_cache_attributes(unsigned int cpu); #ifndef CONFIG_ACPI_PPTT /*
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]: [ 7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 [ 7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111 [ 7.560796] preempt_count: 1, expected: 0 [ 7.560797] RCU nest depth: 1, expected: 1 [ 7.560799] 3 locks held by swapper/111/0: [ 7.560800] #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8 [ 7.560811] #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0 [ 7.560820] #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80 [ 7.560824] irq event stamp: 0 [ 7.560825] hardirqs last enabled at (0): [<0000000000000000>] 0x0 [ 7.560827] hardirqs last disabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8 [ 7.560830] softirqs last enabled at (0): [<ffffc5f8e9f7d594>] copy_process+0x5dc/0x1ab8 [ 7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 7.560834] Preemption disabled at: [ 7.560835] [<ffffc5f8e9fd3c28>] migrate_enable+0x30/0x130 [ 7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G W 6.0.0-rc4-rt6-[...] [ 7.560841] Call trace: [...] [ 7.560870] __kmalloc+0xbc/0x1e8 [ 7.560873] detect_cache_attributes+0x2d4/0x5f0 [ 7.560876] update_siblings_masks+0x30/0x368 [ 7.560880] store_cpu_topology+0x78/0xb8 [ 7.560883] secondary_start_kernel+0xd0/0x198 [ 7.560885] __secondary_switched+0xb0/0xb4 Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> --- drivers/base/arch_topology.c | 10 ++++++- drivers/base/cacheinfo.c | 56 +++++++++++++++++++++++++++++------- include/linux/cacheinfo.h | 1 + 3 files changed, 55 insertions(+), 12 deletions(-)