diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2024-10-07 17:30:49 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-10-17 10:28:07 +0300 |
| commit | 8f3ce3d996bf1e2f8474ec3ddabdb8765c19e6ea (patch) | |
| tree | 22f5c3ebb9f38a173d1bf098cc7445df489e8e1a /include/linux/percpu.h | |
| parent | e142cc87ac4ec618f2ccf5f68aedcd6e28a59d9d (diff) | |
| download | linux-8f3ce3d996bf1e2f8474ec3ddabdb8765c19e6ea.tar.xz | |
mm: percpu: increase PERCPU_DYNAMIC_SIZE_SHIFT on certain builds.
Arnd reported a build failure due to the BUILD_BUG_ON() statement in
alloc_kmem_cache_cpus(). The test
PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu)
The factors that increase the right side of the equation:
- PAGE_SIZE > 4KiB increases KMALLOC_SHIFT_HIGH
- For the local_lock_t in kmem_cache_cpu:
- PREEMPT_RT adds an actual lock.
- LOCKDEP increases the size of the lock.
- LOCK_STAT adds additional bytes plus padding to the lockdep
structure.
The net difference with and without PREEMPT_RT is 88 bytes for the
lock_lock_t, 96 bytes for kmem_cache_cpu due to additional padding. This
is enough to exceed the 80KiB limit with 16KiB page size - the 8KiB page
size is fine.
Increase PERCPU_DYNAMIC_SIZE_SHIFT to 13 on configs with PAGE_SIZE larger
than 4KiB and LOCKDEP enabled.
Link: https://lkml.kernel.org/r/20241007143049.gyMpEu89@linutronix.de
Fixes: d8fccd9ca5f9 ("arm64: Allow to enable PREEMPT_RT.")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202410020326.iaZIteIx-lkp@intel.com/
Reported-by: Arnd Bergmann <arnd@kernel.org>
Closes: https://lore.kernel.org/20241004095702.637528-1-arnd@kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/percpu.h')
| -rw-r--r-- | include/linux/percpu.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/percpu.h b/include/linux/percpu.h index b6321fc49159..52b5ea663b9f 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -41,7 +41,11 @@ PCPU_MIN_ALLOC_SHIFT) #ifdef CONFIG_RANDOM_KMALLOC_CACHES -#define PERCPU_DYNAMIC_SIZE_SHIFT 12 +# if defined(CONFIG_LOCKDEP) && !defined(CONFIG_PAGE_SIZE_4KB) +# define PERCPU_DYNAMIC_SIZE_SHIFT 13 +# else +# define PERCPU_DYNAMIC_SIZE_SHIFT 12 +#endif /* LOCKDEP and PAGE_SIZE > 4KiB */ #else #define PERCPU_DYNAMIC_SIZE_SHIFT 10 #endif |