[PATCH v18 42/42] mm: percpu: increase PERCPU_DYNAMIC_SIZE_SHIFT on DEPT and large PAGE_SIZE
From: Byungchul Park <byungchul@sk.com>
Date: 2025-12-05 07:21:20
Also in:
dri-devel, linux-arch, linux-block, linux-doc, linux-ext4, linux-fsdevel, linux-i2c, linux-ide, linux-media, linux-mm, linux-modules, linux-nfs, linux-rt-devel, lkml, rcu, rust-for-linux
Subsystem:
per-cpu memory allocator, the rest · Maintainers:
Dennis Zhou, Tejun Heo, Christoph Lameter, Linus Torvalds
Yunseong reported a build failure due to the BUILD_BUG_ON() statement in alloc_kmem_cache_cpus(). In the following test: PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu) The following factors increase the right side of the equation: 1. PAGE_SIZE > 4KiB increases KMALLOC_SHIFT_HIGH. 2. DEPT increases the size of the local_lock_t in kmem_cache_cpu. Increase PERCPU_DYNAMIC_SIZE_SHIFT to 11 on configs with PAGE_SIZE larger than 4KiB and DEPT enabled. Reported-by: Yunseong Kim <redacted> Signed-off-by: Byungchul Park <byungchul@sk.com> --- include/linux/percpu.h | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 85bf8dd9f087..dd74321d4bbd 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h@@ -43,7 +43,11 @@ # define PERCPU_DYNAMIC_SIZE_SHIFT 12 #endif /* LOCKDEP and PAGE_SIZE > 4KiB */ #else +#if defined(CONFIG_DEPT) && !defined(CONFIG_PAGE_SIZE_4KB) +#define PERCPU_DYNAMIC_SIZE_SHIFT 11 +#else #define PERCPU_DYNAMIC_SIZE_SHIFT 10 +#endif /* DEPT and PAGE_SIZE > 4KiB */ #endif /*
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2.17.1