> -----Original Message----- > From: Muchun Song [mailto:songmuc...@bytedance.com] > Sent: Tuesday, December 1, 2020 4:19 AM > To: cor...@lwn.net; mike.krav...@oracle.com; t...@linutronix.de; > mi...@redhat.com; b...@alien8.de; x...@kernel.org; h...@zytor.com; > dave.han...@linux.intel.com; l...@kernel.org; pet...@infradead.org; > v...@zeniv.linux.org.uk; a...@linux-foundation.org; paul...@kernel.org; > mchehab+hua...@kernel.org; pawan.kumar.gu...@linux.intel.com; > rdun...@infradead.org; oneu...@suse.com; anshuman.khand...@arm.com; > jroe...@suse.de; almasrym...@google.com; rient...@google.com; > wi...@infradead.org; osalva...@suse.de; mho...@suse.com; Song Bao Hua (Barry > Song) <song.bao....@hisilicon.com> > Cc: duanxiongc...@bytedance.com; linux-...@vger.kernel.org; > linux-kernel@vger.kernel.org; linux...@kvack.org; > linux-fsde...@vger.kernel.org; Muchun Song <songmuc...@bytedance.com> > Subject: [PATCH v7 13/15] mm/hugetlb: Add a kernel parameter > hugetlb_free_vmemmap > > Add a kernel parameter hugetlb_free_vmemmap to disable the feature of > freeing unused vmemmap pages associated with each hugetlb page on boot. > > Signed-off-by: Muchun Song <songmuc...@bytedance.com> Reviewed-by: Barry Song <song.bao....@hisilicon.com> > --- > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ > arch/x86/mm/init_64.c | 5 +++-- > include/linux/hugetlb.h | 19 +++++++++++++++++++ > mm/hugetlb_vmemmap.c | 18 +++++++++++++++++- > 5 files changed, 51 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index 3ae25630a223..9e6854f21d55 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1551,6 +1551,15 @@ > Documentation/admin-guide/mm/hugetlbpage.rst. > Format: size[KMG] > > + hugetlb_free_vmemmap= > + [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, > + this controls freeing unused vmemmap pages associated > + with each HugeTLB page. > + Format: { on | off (default) } > + > + on: enable the feature > + off: disable the feature > + > hung_task_panic= > [KNL] Should the hung task detector generate panics. > Format: 0 | 1 > diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst > b/Documentation/admin-guide/mm/hugetlbpage.rst > index f7b1c7462991..6a8b57f6d3b7 100644 > --- a/Documentation/admin-guide/mm/hugetlbpage.rst > +++ b/Documentation/admin-guide/mm/hugetlbpage.rst > @@ -145,6 +145,9 @@ default_hugepagesz > > will all result in 256 2M huge pages being allocated. Valid default > huge page size is architecture dependent. > +hugetlb_free_vmemmap > + When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing > + unused vmemmap pages associated each HugeTLB page. > > When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` > indicates the current number of pre-allocated huge pages of the default size. > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 155cb06a6961..fcdc020904a8 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -34,6 +34,7 @@ > #include <linux/gfp.h> > #include <linux/kcore.h> > #include <linux/bootmem_info.h> > +#include <linux/hugetlb.h> > > #include <asm/processor.h> > #include <asm/bios_ebda.h> > @@ -1557,7 +1558,7 @@ int __meminit vmemmap_populate(unsigned long start, > unsigned long end, int node, > { > int err; > > - if (IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP)) > + if (is_hugetlb_free_vmemmap_enabled()) > err = vmemmap_populate_basepages(start, end, node, NULL); > else if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > err = vmemmap_populate_basepages(start, end, node, NULL); > @@ -1613,7 +1614,7 @@ void register_page_bootmem_memmap(unsigned long > section_nr, > get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO); > > if (!boot_cpu_has(X86_FEATURE_PSE) || > - IS_ENABLED(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP)) { > + is_hugetlb_free_vmemmap_enabled()) { > next = (addr + PAGE_SIZE) & PAGE_MASK; > pmd = pmd_offset(pud, addr); > if (pmd_none(*pmd)) > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 4efeccb7192c..66d82ae7b712 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -773,6 +773,20 @@ static inline void huge_ptep_modify_prot_commit(struct > vm_area_struct *vma, > } > #endif > > +#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP > +extern bool hugetlb_free_vmemmap_enabled; > + > +static inline bool is_hugetlb_free_vmemmap_enabled(void) > +{ > + return hugetlb_free_vmemmap_enabled; > +} > +#else > +static inline bool is_hugetlb_free_vmemmap_enabled(void) > +{ > + return false; > +} > +#endif > + > #else /* CONFIG_HUGETLB_PAGE */ > struct hstate {}; > > @@ -926,6 +940,11 @@ static inline void set_huge_swap_pte_at(struct mm_struct > *mm, unsigned long addr > pte_t *ptep, pte_t pte, unsigned long > sz) > { > } > + > +static inline bool is_hugetlb_free_vmemmap_enabled(void) > +{ > + return false; > +} > #endif /* CONFIG_HUGETLB_PAGE */ > > static inline spinlock_t *huge_pte_lock(struct hstate *h, > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index a3714db7f400..ebc710d148e4 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -131,6 +131,21 @@ typedef void (*vmemmap_remap_pte_func_t)(struct page > *reuse, pte_t *pte, > unsigned long start, unsigned long end, > void *priv); > > +bool hugetlb_free_vmemmap_enabled; > + > +static int __init early_hugetlb_free_vmemmap_param(char *buf) > +{ > + if (!buf) > + return -EINVAL; > + > + if (!strcmp(buf, "on")) > + hugetlb_free_vmemmap_enabled = true; > + else if (strcmp(buf, "off")) > + return -EINVAL; > + > + return 0; > +} > +early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); > > static inline unsigned int vmemmap_pages_per_hpage(struct hstate *h) > { > @@ -325,7 +340,8 @@ void __init hugetlb_vmemmap_init(struct hstate *h) > unsigned int nr_pages = pages_per_huge_page(h); > unsigned int vmemmap_pages; > > - if (!is_power_of_2(sizeof(struct page))) { > + if (!is_power_of_2(sizeof(struct page)) || > + !hugetlb_free_vmemmap_enabled) { > pr_info("disable freeing vmemmap pages for %s\n", h->name); > return; > } > -- > 2.11.0 Thanks Barry
