6.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 661f951e371cc134ea31c84238dbdc9a898b8403 ]
Leon [1] and Vinicius [2] noted a topology_span_sane() warning during their testing starting from v6.16-rc1. Debug that followed pointed to the tl->mask() for the NODE domain being incorrectly resolved to that of the highest NUMA domain.
tl->mask() for NODE is set to the sd_numa_mask() which depends on the global "sched_domains_curr_level" hack. "sched_domains_curr_level" is set to the "tl->numa_level" during tl traversal in build_sched_domains() calling sd_init() but was not reset before topology_span_sane().
Since "tl->numa_level" still reflected the old value from build_sched_domains(), topology_span_sane() for the NODE domain trips when the span of the last NUMA domain overlaps.
Instead of replicating the "sched_domains_curr_level" hack, get rid of it entirely and instead, pass the entire "sched_domain_topology_level" object to tl->cpumask() function to prevent such mishap in the future.
sd_numa_mask() now directly references "tl->numa_level" instead of relying on the global "sched_domains_curr_level" hack to index into sched_domains_numa_masks[].
The original warning was reproducible on the following NUMA topology reported by Leon:
$ sudo numactl -H available: 5 nodes (0-4) node 0 cpus: 0 1 node 0 size: 2927 MB node 0 free: 1603 MB node 1 cpus: 2 3 node 1 size: 3023 MB node 1 free: 3008 MB node 2 cpus: 4 5 node 2 size: 3023 MB node 2 free: 3007 MB node 3 cpus: 6 7 node 3 size: 3023 MB node 3 free: 3002 MB node 4 cpus: 8 9 node 4 size: 3022 MB node 4 free: 2718 MB node distances: node 0 1 2 3 4 0: 10 39 38 37 36 1: 39 10 38 37 36 2: 38 38 10 37 36 3: 37 37 37 10 36 4: 36 36 36 36 10
The above topology can be mimicked using the following QEMU cmd that was used to reproduce the warning and test the fix:
sudo qemu-system-x86_64 -enable-kvm -cpu host \ -m 20G -smp cpus=10,sockets=10 -machine q35 \ -object memory-backend-ram,size=4G,id=m0 \ -object memory-backend-ram,size=4G,id=m1 \ -object memory-backend-ram,size=4G,id=m2 \ -object memory-backend-ram,size=4G,id=m3 \ -object memory-backend-ram,size=4G,id=m4 \ -numa node,cpus=0-1,memdev=m0,nodeid=0 \ -numa node,cpus=2-3,memdev=m1,nodeid=1 \ -numa node,cpus=4-5,memdev=m2,nodeid=2 \ -numa node,cpus=6-7,memdev=m3,nodeid=3 \ -numa node,cpus=8-9,memdev=m4,nodeid=4 \ -numa dist,src=0,dst=1,val=39 \ -numa dist,src=0,dst=2,val=38 \ -numa dist,src=0,dst=3,val=37 \ -numa dist,src=0,dst=4,val=36 \ -numa dist,src=1,dst=0,val=39 \ -numa dist,src=1,dst=2,val=38 \ -numa dist,src=1,dst=3,val=37 \ -numa dist,src=1,dst=4,val=36 \ -numa dist,src=2,dst=0,val=38 \ -numa dist,src=2,dst=1,val=38 \ -numa dist,src=2,dst=3,val=37 \ -numa dist,src=2,dst=4,val=36 \ -numa dist,src=3,dst=0,val=37 \ -numa dist,src=3,dst=1,val=37 \ -numa dist,src=3,dst=2,val=37 \ -numa dist,src=3,dst=4,val=36 \ -numa dist,src=4,dst=0,val=36 \ -numa dist,src=4,dst=1,val=36 \ -numa dist,src=4,dst=2,val=36 \ -numa dist,src=4,dst=3,val=36 \ ...
[ prateek: Moved common functions to include/linux/sched/topology.h, reuse the common bits for s390 and ppc, commit message ]
Closes: https://lore.kernel.org/lkml/20250610110701.GA256154@unreal/ [1] Fixes: ccf74128d66c ("sched/topology: Assert non-NUMA topology masks don't (partially) overlap") # ce29a7da84cd, f55dac1dafb3 Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reported-by: Leon Romanovsky leon@kernel.org Signed-off-by: K Prateek Nayak kprateek.nayak@amd.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Valentin Schneider vschneid@redhat.com Reviewed-by: Shrikanth Hegde sshegde@linux.ibm.com Tested-by: Valentin Schneider vschneid@redhat.com # x86 Tested-by: Shrikanth Hegde sshegde@linux.ibm.com # powerpc Link: https://lore.kernel.org/lkml/a3de98387abad28592e6ab591f3ff6107fe01dc1.175589... [2] Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/Kconfig | 4 ++++ arch/powerpc/include/asm/topology.h | 2 ++ arch/powerpc/kernel/smp.c | 27 +++++++++++---------------- arch/s390/kernel/topology.c | 20 +++++++------------- arch/x86/kernel/smpboot.c | 8 ++++---- include/linux/sched/topology.h | 28 +++++++++++++++++++++++++++- include/linux/topology.h | 2 +- kernel/sched/topology.c | 28 ++++++++++------------------ 8 files changed, 66 insertions(+), 53 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 93402a1d9c9fc..e51a595a06228 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -971,6 +971,10 @@ config SCHED_SMT when dealing with POWER5 cpus at a cost of slightly increased overhead in some places. If unsure say N here.
+config SCHED_MC + def_bool y + depends on SMP + config PPC_DENORMALISATION bool "PowerPC denormalisation exception handling" depends on PPC_BOOK3S_64 diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h index da15b5efe8071..f19ca44512d1e 100644 --- a/arch/powerpc/include/asm/topology.h +++ b/arch/powerpc/include/asm/topology.h @@ -131,6 +131,8 @@ static inline int cpu_to_coregroup_id(int cpu) #ifdef CONFIG_SMP #include <asm/cputable.h>
+struct cpumask *cpu_coregroup_mask(int cpu); + #ifdef CONFIG_PPC64 #include <asm/smp.h>
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index f59e4b9cc2074..68edb66c2964b 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1028,19 +1028,19 @@ static int powerpc_shared_proc_flags(void) * We can't just pass cpu_l2_cache_mask() directly because * returns a non-const pointer and the compiler barfs on that. */ -static const struct cpumask *shared_cache_mask(int cpu) +static const struct cpumask *tl_cache_mask(struct sched_domain_topology_level *tl, int cpu) { return per_cpu(cpu_l2_cache_map, cpu); }
#ifdef CONFIG_SCHED_SMT -static const struct cpumask *smallcore_smt_mask(int cpu) +static const struct cpumask *tl_smallcore_smt_mask(struct sched_domain_topology_level *tl, int cpu) { return cpu_smallcore_mask(cpu); } #endif
-static struct cpumask *cpu_coregroup_mask(int cpu) +struct cpumask *cpu_coregroup_mask(int cpu) { return per_cpu(cpu_coregroup_map, cpu); } @@ -1054,11 +1054,6 @@ static bool has_coregroup_support(void) return coregroup_enabled; }
-static const struct cpumask *cpu_mc_mask(int cpu) -{ - return cpu_coregroup_mask(cpu); -} - static int __init init_big_cores(void) { int cpu; @@ -1448,7 +1443,7 @@ static bool update_mask_by_l2(int cpu, cpumask_var_t *mask) return false; }
- cpumask_and(*mask, cpu_online_mask, cpu_cpu_mask(cpu)); + cpumask_and(*mask, cpu_online_mask, cpu_node_mask(cpu));
/* Update l2-cache mask with all the CPUs that are part of submask */ or_cpumasks_related(cpu, cpu, submask_fn, cpu_l2_cache_mask); @@ -1538,7 +1533,7 @@ static void update_coregroup_mask(int cpu, cpumask_var_t *mask) return; }
- cpumask_and(*mask, cpu_online_mask, cpu_cpu_mask(cpu)); + cpumask_and(*mask, cpu_online_mask, cpu_node_mask(cpu));
/* Update coregroup mask with all the CPUs that are part of submask */ or_cpumasks_related(cpu, cpu, submask_fn, cpu_coregroup_mask); @@ -1601,7 +1596,7 @@ static void add_cpu_to_masks(int cpu)
/* If chip_id is -1; limit the cpu_core_mask to within PKG */ if (chip_id == -1) - cpumask_and(mask, mask, cpu_cpu_mask(cpu)); + cpumask_and(mask, mask, cpu_node_mask(cpu));
for_each_cpu(i, mask) { if (chip_id == cpu_to_chip_id(i)) { @@ -1701,22 +1696,22 @@ static void __init build_sched_topology(void) if (has_big_cores) { pr_info("Big cores detected but using small core scheduling\n"); powerpc_topology[i++] = - SDTL_INIT(smallcore_smt_mask, powerpc_smt_flags, SMT); + SDTL_INIT(tl_smallcore_smt_mask, powerpc_smt_flags, SMT); } else { - powerpc_topology[i++] = SDTL_INIT(cpu_smt_mask, powerpc_smt_flags, SMT); + powerpc_topology[i++] = SDTL_INIT(tl_smt_mask, powerpc_smt_flags, SMT); } #endif if (shared_caches) { powerpc_topology[i++] = - SDTL_INIT(shared_cache_mask, powerpc_shared_cache_flags, CACHE); + SDTL_INIT(tl_cache_mask, powerpc_shared_cache_flags, CACHE); }
if (has_coregroup_support()) { powerpc_topology[i++] = - SDTL_INIT(cpu_mc_mask, powerpc_shared_proc_flags, MC); + SDTL_INIT(tl_mc_mask, powerpc_shared_proc_flags, MC); }
- powerpc_topology[i++] = SDTL_INIT(cpu_cpu_mask, powerpc_shared_proc_flags, PKG); + powerpc_topology[i++] = SDTL_INIT(tl_pkg_mask, powerpc_shared_proc_flags, PKG);
/* There must be one trailing NULL entry left. */ BUG_ON(i >= ARRAY_SIZE(powerpc_topology) - 1); diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c index 46569b8e47dde..1594c80e9bc4d 100644 --- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -509,33 +509,27 @@ int topology_cpu_init(struct cpu *cpu) return rc; }
-static const struct cpumask *cpu_thread_mask(int cpu) -{ - return &cpu_topology[cpu].thread_mask; -} - - const struct cpumask *cpu_coregroup_mask(int cpu) { return &cpu_topology[cpu].core_mask; }
-static const struct cpumask *cpu_book_mask(int cpu) +static const struct cpumask *tl_book_mask(struct sched_domain_topology_level *tl, int cpu) { return &cpu_topology[cpu].book_mask; }
-static const struct cpumask *cpu_drawer_mask(int cpu) +static const struct cpumask *tl_drawer_mask(struct sched_domain_topology_level *tl, int cpu) { return &cpu_topology[cpu].drawer_mask; }
static struct sched_domain_topology_level s390_topology[] = { - SDTL_INIT(cpu_thread_mask, cpu_smt_flags, SMT), - SDTL_INIT(cpu_coregroup_mask, cpu_core_flags, MC), - SDTL_INIT(cpu_book_mask, NULL, BOOK), - SDTL_INIT(cpu_drawer_mask, NULL, DRAWER), - SDTL_INIT(cpu_cpu_mask, NULL, PKG), + SDTL_INIT(tl_smt_mask, cpu_smt_flags, SMT), + SDTL_INIT(tl_mc_mask, cpu_core_flags, MC), + SDTL_INIT(tl_book_mask, NULL, BOOK), + SDTL_INIT(tl_drawer_mask, NULL, DRAWER), + SDTL_INIT(tl_pkg_mask, NULL, PKG), { NULL, }, };
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 33e166f6ab122..eb289abece237 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -479,14 +479,14 @@ static int x86_cluster_flags(void) static bool x86_has_numa_in_package;
static struct sched_domain_topology_level x86_topology[] = { - SDTL_INIT(cpu_smt_mask, cpu_smt_flags, SMT), + SDTL_INIT(tl_smt_mask, cpu_smt_flags, SMT), #ifdef CONFIG_SCHED_CLUSTER - SDTL_INIT(cpu_clustergroup_mask, x86_cluster_flags, CLS), + SDTL_INIT(tl_cls_mask, x86_cluster_flags, CLS), #endif #ifdef CONFIG_SCHED_MC - SDTL_INIT(cpu_coregroup_mask, x86_core_flags, MC), + SDTL_INIT(tl_mc_mask, x86_core_flags, MC), #endif - SDTL_INIT(cpu_cpu_mask, x86_sched_itmt_flags, PKG), + SDTL_INIT(tl_pkg_mask, x86_sched_itmt_flags, PKG), { NULL }, };
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 5263746b63e8c..a3a24e115d446 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -30,11 +30,19 @@ struct sd_flag_debug { }; extern const struct sd_flag_debug sd_flag_debug[];
+struct sched_domain_topology_level; + #ifdef CONFIG_SCHED_SMT static inline int cpu_smt_flags(void) { return SD_SHARE_CPUCAPACITY | SD_SHARE_LLC; } + +static inline const +struct cpumask *tl_smt_mask(struct sched_domain_topology_level *tl, int cpu) +{ + return cpu_smt_mask(cpu); +} #endif
#ifdef CONFIG_SCHED_CLUSTER @@ -42,6 +50,12 @@ static inline int cpu_cluster_flags(void) { return SD_CLUSTER | SD_SHARE_LLC; } + +static inline const +struct cpumask *tl_cls_mask(struct sched_domain_topology_level *tl, int cpu) +{ + return cpu_clustergroup_mask(cpu); +} #endif
#ifdef CONFIG_SCHED_MC @@ -49,8 +63,20 @@ static inline int cpu_core_flags(void) { return SD_SHARE_LLC; } + +static inline const +struct cpumask *tl_mc_mask(struct sched_domain_topology_level *tl, int cpu) +{ + return cpu_coregroup_mask(cpu); +} #endif
+static inline const +struct cpumask *tl_pkg_mask(struct sched_domain_topology_level *tl, int cpu) +{ + return cpu_node_mask(cpu); +} + #ifdef CONFIG_NUMA static inline int cpu_numa_flags(void) { @@ -172,7 +198,7 @@ bool cpus_equal_capacity(int this_cpu, int that_cpu); bool cpus_share_cache(int this_cpu, int that_cpu); bool cpus_share_resources(int this_cpu, int that_cpu);
-typedef const struct cpumask *(*sched_domain_mask_f)(int cpu); +typedef const struct cpumask *(*sched_domain_mask_f)(struct sched_domain_topology_level *tl, int cpu); typedef int (*sched_domain_flags_f)(void);
struct sd_data { diff --git a/include/linux/topology.h b/include/linux/topology.h index 33b7fda97d390..6575af39fd10f 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -260,7 +260,7 @@ static inline bool topology_is_primary_thread(unsigned int cpu)
#endif
-static inline const struct cpumask *cpu_cpu_mask(int cpu) +static inline const struct cpumask *cpu_node_mask(int cpu) { return cpumask_of_node(cpu_to_node(cpu)); } diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 6e2f54169e66c..36d4f9f063516 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1591,7 +1591,6 @@ static void claim_allocations(int cpu, struct sched_domain *sd) enum numa_topology_type sched_numa_topology_type;
static int sched_domains_numa_levels; -static int sched_domains_curr_level;
int sched_max_numa_distance; static int *sched_domains_numa_distance; @@ -1632,14 +1631,7 @@ sd_init(struct sched_domain_topology_level *tl, int sd_id, sd_weight, sd_flags = 0; struct cpumask *sd_span;
-#ifdef CONFIG_NUMA - /* - * Ugly hack to pass state to sd_numa_mask()... - */ - sched_domains_curr_level = tl->numa_level; -#endif - - sd_weight = cpumask_weight(tl->mask(cpu)); + sd_weight = cpumask_weight(tl->mask(tl, cpu));
if (tl->sd_flags) sd_flags = (*tl->sd_flags)(); @@ -1677,7 +1669,7 @@ sd_init(struct sched_domain_topology_level *tl, };
sd_span = sched_domain_span(sd); - cpumask_and(sd_span, cpu_map, tl->mask(cpu)); + cpumask_and(sd_span, cpu_map, tl->mask(tl, cpu)); sd_id = cpumask_first(sd_span);
sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map); @@ -1737,17 +1729,17 @@ sd_init(struct sched_domain_topology_level *tl, */ static struct sched_domain_topology_level default_topology[] = { #ifdef CONFIG_SCHED_SMT - SDTL_INIT(cpu_smt_mask, cpu_smt_flags, SMT), + SDTL_INIT(tl_smt_mask, cpu_smt_flags, SMT), #endif
#ifdef CONFIG_SCHED_CLUSTER - SDTL_INIT(cpu_clustergroup_mask, cpu_cluster_flags, CLS), + SDTL_INIT(tl_cls_mask, cpu_cluster_flags, CLS), #endif
#ifdef CONFIG_SCHED_MC - SDTL_INIT(cpu_coregroup_mask, cpu_core_flags, MC), + SDTL_INIT(tl_mc_mask, cpu_core_flags, MC), #endif - SDTL_INIT(cpu_cpu_mask, NULL, PKG), + SDTL_INIT(tl_pkg_mask, NULL, PKG), { NULL, }, };
@@ -1769,9 +1761,9 @@ void __init set_sched_topology(struct sched_domain_topology_level *tl)
#ifdef CONFIG_NUMA
-static const struct cpumask *sd_numa_mask(int cpu) +static const struct cpumask *sd_numa_mask(struct sched_domain_topology_level *tl, int cpu) { - return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)]; + return sched_domains_numa_masks[tl->numa_level][cpu_to_node(cpu)]; }
static void sched_numa_warn(const char *str) @@ -2413,7 +2405,7 @@ static bool topology_span_sane(const struct cpumask *cpu_map) * breaks the linking done for an earlier span. */ for_each_cpu(cpu, cpu_map) { - const struct cpumask *tl_cpu_mask = tl->mask(cpu); + const struct cpumask *tl_cpu_mask = tl->mask(tl, cpu); int id;
/* lowest bit set in this mask is used as a unique id */ @@ -2421,7 +2413,7 @@ static bool topology_span_sane(const struct cpumask *cpu_map)
if (cpumask_test_cpu(id, id_seen)) { /* First CPU has already been seen, ensure identical spans */ - if (!cpumask_equal(tl->mask(id), tl_cpu_mask)) + if (!cpumask_equal(tl->mask(tl, id), tl_cpu_mask)) return false; } else { /* First CPU hasn't been seen before, ensure it's a completely new span */