From c451fde27db0bbb3b0f48b6c752e222c3a8a2191 Mon Sep 17 00:00:00 2001 From: Ricardo Neri Date: Mon, 4 Mar 2024 18:32:04 +0800 Subject: [PATCH] UBUNTU: SAUCE: cacheinfo: Allocate memory for memory if not done from the primary CPU BugLink: https://bugs.launchpad.net/bugs/2049793 Commit 5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU") adds functionality that architectures can use to optionally allocate and build cacheinfo early during boot. Commit 6539cffa9495 ("cacheinfo: Add arch specific early level initializer") lets secondary CPUs correct (and reallocate memory) cacheinfo data if needed. If the early build functionality is not used and cacheinfo does not need correction, memory for cacheinfo is never allocated. x86 does not use the early build functionality. Consequently, during the cacheinfo CPU hotplug callback, last_level_cache_is_valid() attempts to dereference a NULL pointer: BUG: kernel NULL pointer dereference, address: 0000000000000100 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not present page PGD 0 P4D 0 Oops: 0000 [#1] PREEPMT SMP NOPTI CPU: 0 PID 19 Comm: cpuhp/0 Not tainted 6.4.0-rc2 #1 RIP: 0010: last_level_cache_is_valid+0x95/0xe0a Allocate memory for cacheinfo during the cacheinfo CPU hotplug callback if not done earlier. Cc: Andreas Herrmann Cc: Catalin Marinas Cc: Chen Yu Cc: Huang Ying Cc: Len Brown Cc: Radu Rendec Cc: Pierre Gondois Cc: Pu Wen Cc: "Rafael J. Wysocki" Cc: Sudeep Holla Cc: Srinivas Pandruvada Cc: Will Deacon Cc: Zhang Rui Cc: linux-arm-kernel@lists.infradead.org Cc: stable@vger.kernel.org Reviewed-by: Radu Rendec Reviewed-by: Sudeep Holla Fixes: 6539cffa9495 ("cacheinfo: Add arch specific early level initializer") Signed-off-by: Ricardo Neri (cherry-picked from https://lore.kernel.org/all/20231212222519.12834-3-ricardo.neri-calderon@linux.intel.com/raw) Signed-off-by: You-Sheng Yang Signed-off-by: Paolo Pisati --- drivers/base/cacheinfo.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index 967c5cf3fb1d..735ccead190e 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -557,7 +557,11 @@ static inline int init_level_allocate_ci(unsigned int cpu) */ ci_cacheinfo(cpu)->early_ci_levels = false; - if (cache_leaves(cpu) <= early_leaves) + /* + * Some architectures (e.g., x86) do not use early initialization. + * Allocate memory now in such case. + */ + if (cache_leaves(cpu) <= early_leaves && per_cpu_cacheinfo(cpu)) return 0; kfree(per_cpu_cacheinfo(cpu));