On 8 Aug 2021, at 4:23, Mike Rapoport wrote: > On Thu, Aug 05, 2021 at 03:02:52PM -0400, Zi Yan wrote: >> From: Zi Yan >> >> For other MAX_ORDER uses (described below), there is no need or too much >> hassle to convert certain static array to dynamic ones. Add >> MIN_MAX_ORDER to serve as compile time constant in place of MAX_ORDER. >> >> ARM64 hypervisor maintains its own free page list and does not import >> any core kernel symbols, so soon-to-be runtime variable MAX_ORDER is not >> accessible in ARM64 hypervisor code. Also there is no need to allocating >> very large pages. >> >> In SLAB/SLOB/SLUB, 2-D array kmalloc_caches uses MAX_ORDER in its second >> dimension. It is too much hassle to allocate memory for kmalloc_caches >> before any proper memory allocator is set up. >> >> Signed-off-by: Zi Yan >> Cc: Marc Zyngier >> Cc: Catalin Marinas >> Cc: Christoph Lameter >> Cc: Vlastimil Babka >> Cc: Quentin Perret >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: kvmarm@lists.cs.columbia.edu >> Cc: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org >> --- >> arch/arm64/kvm/hyp/include/nvhe/gfp.h | 2 +- >> arch/arm64/kvm/hyp/nvhe/page_alloc.c | 3 ++- >> include/linux/mmzone.h | 3 +++ >> include/linux/slab.h | 8 ++++---- >> mm/slab.c | 2 +- >> mm/slub.c | 7 ++++--- >> 6 files changed, 15 insertions(+), 10 deletions(-) >> >> diff --git a/arch/arm64/kvm/hyp/include/nvhe/gfp.h b/arch/arm64/kvm/hyp/include/nvhe/gfp.h >> index fb0f523d1492..c774b4a98336 100644 >> --- a/arch/arm64/kvm/hyp/include/nvhe/gfp.h >> +++ b/arch/arm64/kvm/hyp/include/nvhe/gfp.h >> @@ -16,7 +16,7 @@ struct hyp_pool { >> * API at EL2. >> */ >> hyp_spinlock_t lock; >> - struct list_head free_area[MAX_ORDER]; >> + struct list_head free_area[MIN_MAX_ORDER]; >> phys_addr_t range_start; >> phys_addr_t range_end; >> unsigned short max_order; >> diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c >> index 41fc25bdfb34..a1cc1b648de0 100644 >> --- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c >> +++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c >> @@ -226,7 +226,8 @@ int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages, >> int i; >> >> hyp_spin_lock_init(&pool->lock); >> - pool->max_order = min(MAX_ORDER, get_order(nr_pages << PAGE_SHIFT)); >> + >> + pool->max_order = min(MIN_MAX_ORDER, get_order(nr_pages << PAGE_SHIFT)); >> for (i = 0; i < pool->max_order; i++) >> INIT_LIST_HEAD(&pool->free_area[i]); >> pool->range_start = phys; >> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h >> index 09aafc05aef4..379dada82d4b 100644 >> --- a/include/linux/mmzone.h >> +++ b/include/linux/mmzone.h >> @@ -27,11 +27,14 @@ >> #ifndef CONFIG_ARCH_FORCE_MAX_ORDER >> #ifdef CONFIG_SET_MAX_ORDER >> #define MAX_ORDER CONFIG_SET_MAX_ORDER >> +#define MIN_MAX_ORDER CONFIG_SET_MAX_ORDER >> #else >> #define MAX_ORDER 11 >> +#define MIN_MAX_ORDER MAX_ORDER >> #endif /* CONFIG_SET_MAX_ORDER */ >> #else >> #define MAX_ORDER CONFIG_ARCH_FORCE_MAX_ORDER >> +#define MIN_MAX_ORDER CONFIG_ARCH_FORCE_MAX_ORDER >> #endif /* CONFIG_ARCH_FORCE_MAX_ORDER */ >> #define MAX_ORDER_NR_PAGES (1 << (MAX_ORDER - 1)) > > The end result of this #ifdef explosion looks entirely unreadable: Just to clarify the use of #ifdef: MAX_ORDER is changed to a boot time variable and it cannot be used for static array declaration, so I added MIN_MAX_ORDER. At the moment, there are three cases of setting MAX_ORDER and MIN_MAX_ORDER: 1. CONFIG_ARCH_FORCE_MAX_ORDER tells the MAX_ORDER certain arch needs at compilation time. 2. CONFIG_SET_MAX_ORDER allows to change MAX_ORDER when an arch does not set its MAX_ORER and SPARSEMEM_VMEMMAP is set. 3. !SPARSEMEM_VMEMMAP and no CONFIG_ARCH_FORCE_MAX_ORDER, then MAX_ORDER is set to 11 by default. I agree the code is hard to read, I will clean this up. > > /* Free memory management - zoned buddy allocator. */ > #ifndef CONFIG_ARCH_FORCE_MAX_ORDER > #ifdef CONFIG_SET_MAX_ORDER > /* Defined in mm/page_alloc.c */ > extern int buddy_alloc_max_order; > > #define MAX_ORDER buddy_alloc_max_order > #define MIN_MAX_ORDER CONFIG_SET_MAX_ORDER > #else > #define MAX_ORDER 11 > #define MIN_MAX_ORDER MAX_ORDER > #endif /* CONFIG_SET_MAX_ORDER */ > #else > > #ifdef CONFIG_SPARSEMEM_VMEMMAP > /* Defined in mm/page_alloc.c */ > extern int buddy_alloc_max_order; > > #define MAX_ORDER buddy_alloc_max_order > #else > #define MAX_ORDER CONFIG_ARCH_FORCE_MAX_ORDER > #endif /* CONFIG_SPARSEMEM_VMEMMAP */ > #define MIN_MAX_ORDER CONFIG_ARCH_FORCE_MAX_ORDER > #endif /* CONFIG_ARCH_FORCE_MAX_ORDER */ > >> diff --git a/include/linux/slab.h b/include/linux/slab.h >> index 2c0d80cca6b8..d8747c158db6 100644 >> --- a/include/linux/slab.h >> +++ b/include/linux/slab.h >> @@ -244,8 +244,8 @@ static inline void __check_heap_object(const void *ptr, unsigned long n, >> * to do various tricks to work around compiler limitations in order to >> * ensure proper constant folding. >> */ >> -#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \ >> - (MAX_ORDER + PAGE_SHIFT - 1) : 25) >> +#define KMALLOC_SHIFT_HIGH ((MIN_MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \ >> + (MIN_MAX_ORDER + PAGE_SHIFT - 1) : 25) >> #define KMALLOC_SHIFT_MAX KMALLOC_SHIFT_HIGH >> #ifndef KMALLOC_SHIFT_LOW >> #define KMALLOC_SHIFT_LOW 5 >> @@ -258,7 +258,7 @@ static inline void __check_heap_object(const void *ptr, unsigned long n, >> * (PAGE_SIZE*2). Larger requests are passed to the page allocator. >> */ >> #define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1) >> -#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1) >> +#define KMALLOC_SHIFT_MAX (MIN_MAX_ORDER + PAGE_SHIFT - 1) >> #ifndef KMALLOC_SHIFT_LOW >> #define KMALLOC_SHIFT_LOW 3 >> #endif >> @@ -271,7 +271,7 @@ static inline void __check_heap_object(const void *ptr, unsigned long n, >> * be allocated from the same page. >> */ >> #define KMALLOC_SHIFT_HIGH PAGE_SHIFT >> -#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT - 1) >> +#define KMALLOC_SHIFT_MAX (MIN_MAX_ORDER + PAGE_SHIFT - 1) >> #ifndef KMALLOC_SHIFT_LOW >> #define KMALLOC_SHIFT_LOW 3 >> #endif >> diff --git a/mm/slab.c b/mm/slab.c >> index d0f725637663..0041de8ec0e9 100644 >> --- a/mm/slab.c >> +++ b/mm/slab.c >> @@ -466,7 +466,7 @@ static int __init slab_max_order_setup(char *str) >> { >> get_option(&str, &slab_max_order); >> slab_max_order = slab_max_order < 0 ? 0 : >> - min(slab_max_order, MAX_ORDER - 1); >> + min(slab_max_order, MIN_MAX_ORDER - 1); >> slab_max_order_set = true; >> >> return 1; >> diff --git a/mm/slub.c b/mm/slub.c >> index b6c5205252eb..228e4a77c678 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -3564,8 +3564,9 @@ static inline int calculate_order(unsigned int size) >> /* >> * Doh this slab cannot be placed using slub_max_order. >> */ >> - order = slab_order(size, 1, MAX_ORDER, 1); >> - if (order < MAX_ORDER) >> + >> + order = slab_order(size, 1, MIN_MAX_ORDER, 1); >> + if (order < MIN_MAX_ORDER) >> return order; >> return -ENOSYS; >> } >> @@ -4079,7 +4080,7 @@ __setup("slub_min_order=", setup_slub_min_order); >> static int __init setup_slub_max_order(char *str) >> { >> get_option(&str, (int *)&slub_max_order); >> - slub_max_order = min(slub_max_order, (unsigned int)MAX_ORDER - 1); >> + slub_max_order = min(slub_max_order, (unsigned int)MIN_MAX_ORDER - 1); >> >> return 1; >> } >> -- >> 2.30.2 >> > > -- > Sincerely yours, > Mike. — Best Regards, Yan, Zi