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e8753e416c
LKP reported a build failure as below on the following patch "mm/slub,
percpu: correct the calculation of early percpu allocation size"
~~~~~~
In file included from <command-line>:
In function 'alloc_kmem_cache_cpus',
inlined from 'kmem_cache_open' at mm/slub.c:4340:6:
>> >> include/linux/compiler_types.h:357:45: error: call to '__compiletime_assert_474' declared with attribute error:
BUILD_BUG_ON failed: PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu)
357 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
~~~~~~
From the kernel config file provided by LKP, the building was made on
arm64 with below Kconfig item enabled:
CONFIG_ZONE_DMA=y
CONFIG_SLUB_CPU_PARTIAL=y
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_SLUB_STATS=y
CONFIG_ARM64_PAGE_SHIFT=16
CONFIG_ARM64_64K_PAGES=y
Then we will have:
NR_KMALLOC_TYPES:4
KMALLOC_SHIFT_HIGH:17
sizeof(struct kmem_cache_cpu):184
The product of them is 12512, which is bigger than PERCPU_DYNAMIC_EARLY_SIZE,
12K. Hence, the BUILD_BUG_ON in alloc_kmem_cache_cpus() is triggered.
Earlier, in commit 099a19d91c ("percpu: allow limited allocation
before slab is online"), PERCPU_DYNAMIC_EARLY_SIZE was introduced and
set to 12K which is equal to the then PERPCU_DYNAMIC_RESERVE.
Later, in commit 1a4d76076c ("percpu: implement asynchronous chunk
population"), PERPCU_DYNAMIC_RESERVE was increased by 8K, while
PERCPU_DYNAMIC_EARLY_SIZE was kept unchanged.
So, here increase PERCPU_DYNAMIC_EARLY_SIZE by 8K too to accommodate to
the slub's requirement.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.