On Wed, 28 Aug 2024 18:07:04 +0200 Mateusz Guzik <mjguzik@xxxxxxxxx> wrote: > The mutex array pointer shares a cacheline with the spinlock: > ffffffff84187480 B hugetlb_fault_mutex_table > ffffffff84187488 B hugetlb_lock Fair enough. My x86_64 defconfig now has num_fault_mutexes: .zero 4 .globl hugetlb_lock .section .data..cacheline_aligned,"aw" .align 64 .type hugetlb_lock, @object .size hugetlb_lock, 4 hugetlb_lock: .zero 4 .section .init.data .align 32 .type default_hugepages_in_node, @object .size default_hugepages_in_node, 256 default_hugepages_in_node: .zero 256 .type parsed_default_hugepagesz, @object .size parsed_default_hugepagesz, 1 which looks good. > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -72,14 +72,14 @@ static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata; > * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages, > * free_huge_pages, and surplus_huge_pages. > */ > -DEFINE_SPINLOCK(hugetlb_lock); > +__cacheline_aligned_in_smp DEFINE_SPINLOCK(hugetlb_lock); > > /* > * Serializes faults on the same logical page. This is used to > * prevent spurious OOMs when the hugepage pool is fully utilized. > */ > -static int num_fault_mutexes; > -struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp; > +static __ro_after_init int num_fault_mutexes; > +__ro_after_init struct mutex *hugetlb_fault_mutex_table; It's conventional (within MM, at least) to put the section thing at the end of the definition, so tweak: --- a/mm/hugetlb.c~mm-hugetlb-sort-out-global-lock-annotations-fix +++ a/mm/hugetlb.c @@ -72,14 +72,14 @@ static unsigned int default_hugepages_in * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages, * free_huge_pages, and surplus_huge_pages. */ -__cacheline_aligned_in_smp DEFINE_SPINLOCK(hugetlb_lock); +DEFINE_SPINLOCK(hugetlb_lock) __cacheline_aligned_in_smp; /* * Serializes faults on the same logical page. This is used to * prevent spurious OOMs when the hugepage pool is fully utilized. */ -static __ro_after_init int num_fault_mutexes; -__ro_after_init struct mutex *hugetlb_fault_mutex_table; +static int num_fault_mutexes __ro_after_init; +struct mutex *hugetlb_fault_mutex_table __ro_after_init; /* Forward declaration */ static int hugetlb_acct_memory(struct hstate *h, long delta); _
