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Wed, 16 Dec 2020 08:04:48 -0800 (PST) MIME-Version: 1.0 References: <20201213154534.54826-1-songmuchun@bytedance.com> <20201213154534.54826-9-songmuchun@bytedance.com> <20201216144052.GF29394@linux> In-Reply-To: <20201216144052.GF29394@linux> From: Muchun Song Date: Thu, 17 Dec 2020 00:04:11 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v9 08/11] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap To: Oscar Salvador Cc: Jonathan Corbet , Mike Kravetz , Thomas Gleixner , mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, Peter Zijlstra , viro@zeniv.linux.org.uk, Andrew Morton , paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, Randy Dunlap , oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, Mina Almasry , David Rientjes , Matthew Wilcox , Michal Hocko , "Song Bao Hua (Barry Song)" , David Hildenbrand , Xiongchun duan , linux-doc@vger.kernel.org, LKML , Linux Memory Management List , linux-fsdevel Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Dec 16, 2020 at 10:40 PM Oscar Salvador wrote: > > On Sun, Dec 13, 2020 at 11:45:31PM +0800, Muchun Song wrote: > > Add a kernel parameter hugetlb_free_vmemmap to disable the feature of > > freeing unused vmemmap pages associated with each hugetlb page on boot. > I guess this should read "to enable the feature"? > AFAICS, it is disabled by default. > > > Signed-off-by: Muchun Song > > Reviewed-by: Oscar Salvador Thanks Oscar. > > > --- > > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > > Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++ > > arch/x86/mm/init_64.c | 8 ++++++-- > > include/linux/hugetlb.h | 19 +++++++++++++++++++ > > mm/hugetlb_vmemmap.c | 16 ++++++++++++++++ > > 5 files changed, 53 insertions(+), 2 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..3a23c2377acc 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 with 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 0435bee2e172..1bce5f20e6ca 100644 > > --- a/arch/x86/mm/init_64.c > > +++ b/arch/x86/mm/init_64.c > > @@ -34,6 +34,7 @@ > > #include > > #include > > #include > > +#include > > > > #include > > #include > > @@ -1557,7 +1558,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, > > { > > int err; > > > > - if (end - start < PAGES_PER_SECTION * sizeof(struct page)) > > + if (is_hugetlb_free_vmemmap_enabled() || > > + end - start < PAGES_PER_SECTION * sizeof(struct page)) > > err = vmemmap_populate_basepages(start, end, node, NULL); > > else if (boot_cpu_has(X86_FEATURE_PSE)) > > err = vmemmap_populate_hugepages(start, end, node, altmap); > > @@ -1585,6 +1587,8 @@ void register_page_bootmem_memmap(unsigned long section_nr, > > pmd_t *pmd; > > unsigned int nr_pmd_pages; > > struct page *page; > > + bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) || > > + is_hugetlb_free_vmemmap_enabled(); > > > > for (; addr < end; addr = next) { > > pte_t *pte = NULL; > > @@ -1610,7 +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)) { > > + if (base_mapping) { > > 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 ebca2ef02212..7f47f0eeca3b 100644 > > --- a/include/linux/hugetlb.h > > +++ b/include/linux/hugetlb.h > > @@ -770,6 +770,20 @@ 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 {}; > > > > @@ -923,6 +937,11 @@ 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 02201c2e3dfa..64ad929cac61 100644 > > --- a/mm/hugetlb_vmemmap.c > > +++ b/mm/hugetlb_vmemmap.c > > @@ -180,6 +180,22 @@ > > #define RESERVE_VMEMMAP_NR 2U > > #define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT) > > > > +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 long free_vmemmap_pages_size_per_hpage(struct hstate *h) > > { > > return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; > > -- > > 2.11.0 > > > > -- > Oscar Salvador > SUSE L3 -- Yours, Muchun