- 01 Jul, 2021 26 commits
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Muchun Song authored
When using HUGETLB_PAGE_FREE_VMEMMAP, the freeing unused vmemmap pages associated with each HugeTLB page is default off. Now the vmemmap is PMD mapped. So there is no side effect when this feature is enabled with no HugeTLB pages in the system. Someone may want to enable this feature in the compiler time instead of using boot command line. So add a config to make it default on when someone do not want to enable it via command line. Link: https://lkml.kernel.org/r/20210616094915.34432-4-songmuchun@bytedance.comSigned-off-by:
Muchun Song <songmuchun@bytedance.com> Cc: Chen Huang <chenhuang5@huawei.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Muchun Song authored
The preparation of splitting huge PMD mapping of vmemmap pages is ready, so switch the mapping from PTE to PMD. Link: https://lkml.kernel.org/r/20210616094915.34432-3-songmuchun@bytedance.comSigned-off-by:
Mike Kravetz <mike.kravetz@oracle.com> Cc: Chen Huang <chenhuang5@huawei.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by:
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Muchun Song authored
Patch series "Split huge PMD mapping of vmemmap pages", v4. In order to reduce the difficulty of code review in series[1]. We disable huge PMD mapping of vmemmap pages when that feature is enabled. In this series, we do not disable huge PMD mapping of vmemmap pages anymore. We will split huge PMD mapping when needed. When HugeTLB pages are freed from the pool we do not attempt coalasce and move back to a PMD mapping because it is much more complex. [1] https://lore.kernel.org/linux-doc/20210510030027.56044-1-songmuchun@bytedance.com/ This patch (of 3): In [1], PMD mappings of vmemmap pages were disabled if the the feature hugetlb_free_vmemmap was enabled. This was done to simplify the initial implementation of vmmemap freeing for hugetlb pages. Now, remove this simplification by allowing PMD mapping and switching to PTE mappings as needed for allocated hugetlb pages. When a hugetlb page is allocated, the vmemmap page tables are walked to free vmemmap pages. During this walk, split huge PMD mappings to PTE mappings as required. In the unlikely case PTE pages can not be allocated, return error(ENOMEM) and do not optimize vmemmap of the hugetlb page. When HugeTLB pages are freed from the pool, we do not attempt to coalesce and move back to a PMD mapping because it is much more complex. [1] https://lkml.kernel.org/r/20210510030027.56044-8-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20210616094915.34432-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20210616094915.34432-2-songmuchun@bytedance.comSigned-off-by:
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Mina Almasry authored
On UFFDIO_COPY, if we fail to copy the page contents while holding the hugetlb_fault_mutex, we will drop the mutex and return to the caller after allocating a page that consumed a reservation. In this case there may be a fault that double consumes the reservation. To handle this, we free the allocated page, fix the reservations, and allocate a temporary hugetlb page and return that to the caller. When the caller does the copy outside of the lock, we again check the cache, and allocate a page consuming the reservation, and copy over the contents. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning and the copy_huge_page_from_user() always fails, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [yuehaibing@huawei.com: remove set but not used variable 'vm_alloc_shared'] Link: https://lkml.kernel.org/r/20210601141610.28332-1-yuehaibing@huawei.com [almasrymina@google.com: fix allocation error check and copy func name] Link: https://lkml.kernel.org/r/20210605010626.1459873-1-almasrymina@google.com Link: https://lkml.kernel.org/r/20210528005029.88088-1-almasrymina@google.comSigned-off-by:Mina Almasry <almasrymina@google.com> Signed-off-by:
YueHaibing <yuehaibing@huawei.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by:
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Nanyong Sun authored
The debug_cow attribute had been removed since commit 4958e4d8 ("mm: thp: remove debug_cow switch"), so remove it in selftest code too, otherwise the khugepaged test will fail. Link: https://lkml.kernel.org/r/20210430051117.400189-1-sunnanyong@huawei.com Fixes: 4958e4d8 ("mm: thp: remove debug_cow switch") Signed-off-by:
Nanyong Sun <sunnanyong@huawei.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by:
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Christophe Leroy authored
powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires vmalloc to support hugepd tables. Link: https://lkml.kernel.org/r/8b972f1c03fb6bd59953035f0a3e4d26659de4f8.1620795204.git.christophe.leroy@csgroup.euSigned-off-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Signed-off-by:
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Christophe Leroy authored
On some architectures like powerpc, there are huge pages that are mapped at pte level. Enable it in vmalloc. For that, architectures can provide arch_vmap_pte_supported_shift() that returns the shift for pages to map at pte level. Link: https://lkml.kernel.org/r/2c717e3b1fba1894d890feb7669f83025bfa314d.1620795204.git.christophe.leroy@csgroup.euSigned-off-by:
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Christophe Leroy authored
On some architectures like powerpc, there are huge pages that are mapped at pte level. Enable it in vmap. For that, architectures can provide arch_vmap_pte_range_map_size() that returns the size of pages to map at pte level. Link: https://lkml.kernel.org/r/fb3ccc73377832ac6708181ec419128a2f98ce36.1620795204.git.christophe.leroy@csgroup.euSigned-off-by:
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Christophe Leroy authored
For architectures with no PMD and/or no PUD, add stubs similar to what we have for architectures without P4D. [christophe.leroy@csgroup.eu: arm64: define only {pud/pmd}_{set/clear}_huge when useful] Link: https://lkml.kernel.org/r/73ec95f40cafbbb69bdfb43a7f53876fd845b0ce.1620990479.git.christophe.leroy@csgroup.eu [christophe.leroy@csgroup.eu: x86: define only {pud/pmd}_{set/clear}_huge when useful] Link: https://lkml.kernel.org/r/7fbf1b6bc3e15c07c24fa45278d57064f14c896b.1620930415.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/5ac5976419350e8e048d463a64cae449eb3ba4b0.1620795204.git.christophe.leroy@csgroup.euSigned-off-by: -
Christophe Leroy authored
Patch series "Subject: [PATCH v2 0/5] Implement huge VMAP and VMALLOC on powerpc 8xx", v2. This series implements huge VMAP and VMALLOC on powerpc 8xx. Powerpc 8xx has 4 page sizes: - 4k - 16k - 512k - 8M At the time being, vmalloc and vmap only support huge pages which are leaf at PMD level. Here the PMD level is 4M, it doesn't correspond to any supported page size. For now, implement use of 16k and 512k pages which is done at PTE level. Support of 8M pages will be implemented later, it requires use of hugepd tables. To allow this, the architecture provides two functions: - arch_vmap_pte_range_map_size() which tells vmap_pte_range() what page size to use. A stub returning PAGE_SIZE is provided when the architecture doesn't provide this function. - arch_vmap_pte_supported_shift() which tells __vmalloc_node_range() what page shift to use for a given area size. A stub returning PAGE_SHIFT is provided when the architecture doesn't provide this function. This patch (of 5): At the time being, arch_make_huge_pte() has the following prototype: pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, struct page *page, int writable); vma is used to get the pages shift or size. vma is also used on Sparc to get vm_flags. page is not used. writable is not used. In order to use this function without a vma, replace vma by shift and flags. Also remove the used parameters. Link: https://lkml.kernel.org/r/cover.1620795204.git.christophe.leroy@csgroup.eu Link: https://lkml.kernel.org/r/f4633ac6a7da2f22f31a04a89e0a7026bb78b15b.1620795204.git.christophe.leroy@csgroup.euSigned-off-by:
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Miaohe Lin authored
If other processes are mapping any other subpages of the hugepage, i.e. in pte-mapped thp case, page_mapcount() will return 1 incorrectly. Then we would discard the page while other processes are still mapping it. Fix it by using total_mapcount() which can tell whether other processes are still mapping it. Link: https://lkml.kernel.org/r/20210511134857.1581273-6-linmiaohe@huawei.com Fixes: b8d3c4c3 ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called") Reviewed-by:
Yang Shi <shy828301@gmail.com> Signed-off-by:
Miaohe Lin <linmiaohe@huawei.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Rik van Riel <riel@surriel.com> Cc: Song Liu <songliubraving@fb.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by:
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Miaohe Lin authored
Commit aa88b68c ("thp: keep huge zero page pinned until tlb flush") introduced tlb_remove_page() for huge zero page to keep it pinned until flush is complete and prevents the page from being split under us. But huge zero page is kept pinned until all relevant mm_users reach zero since the commit 6fcb52a5 ("thp: reduce usage of huge zero page's atomic counter"). So tlb_remove_page_size() for huge zero pmd is unnecessary now. Link: https://lkml.kernel.org/r/20210511134857.1581273-5-linmiaohe@huawei.comReviewed-by:
David Hildenbrand <david@redhat.com> Signed-off-by:
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Miaohe Lin authored
Since commit 99cb0dbd ("mm,thp: add read-only THP support for (non-shmem) FS"), read-only THP file mapping is supported. But it forgot to add checking for it in transparent_hugepage_enabled(). To fix it, we add checking for read-only THP file mapping and also introduce helper transhuge_vma_enabled() to check whether thp is enabled for specified vma to reduce duplicated code. We rename transparent_hugepage_enabled to transparent_hugepage_active to make the code easier to follow as suggested by David Hildenbrand. [linmiaohe@huawei.com: define transhuge_vma_enabled next to transhuge_vma_suitable] Link: https://lkml.kernel.org/r/20210514093007.4117906-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210511134857.1581273-4-linmiaohe@huawei.com Fixes: 99cb0dbd ("mm,thp: add read-only THP support for (non-shmem) FS") Signed-off-by:
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Miaohe Lin authored
Now that we can represent the location of ->deferred_list instead of ->mapping + ->index, make use of it to improve readability. Link: https://lkml.kernel.org/r/20210511134857.1581273-3-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Patch series "Cleanup and fixup for huge_memory:, v3. This series contains cleanups to remove dedicated macro and remove unnecessary tlb_remove_page_size() for huge zero pmd. Also this adds missing read-only THP checking for transparent_hugepage_enabled() and avoids discarding hugepage if other processes are mapping it. More details can be found in the respective changelogs. Thi patch (of 5): Rewrite the pgoff checking logic to remove macro HPAGE_CACHE_INDEX_MASK which is only used here to simplify the code. Link: https://lkml.kernel.org/r/20210511134857.1581273-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210511134857.1581273-2-linmiaohe@huawei.comSigned-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by:
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Shixin Liu authored
Remove redundant pfn_{pmd/pte}() in {pmd/pte}_advanced_tests() and adjust pfn_pud() in pud_advanced_tests() to make it similar with other two functions. In addition, the branch condition should be CONFIG_TRANSPARENT_HUGEPAGE instead of CONFIG_ARCH_HAS_PTE_DEVMAP. Link: https://lkml.kernel.org/r/20210419071820.750217-2-liushixin2@huawei.comSigned-off-by:Shixin Liu <liushixin2@huawei.com> Reviewed-by:
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Shixin Liu authored
The functions {pmd/pud}_set_huge and {pmd/pud}_clear_huge are not dependent on THP. Hence move {pmd/pud}_huge_tests out of CONFIG_TRANSPARENT_HUGEPAGE. Link: https://lkml.kernel.org/r/20210419071820.750217-1-liushixin2@huawei.comSigned-off-by: -
Muchun Song authored
All the infrastructure is ready, so we introduce nr_free_vmemmap_pages field in the hstate to indicate how many vmemmap pages associated with a HugeTLB page that can be freed to buddy allocator. And initialize it in the hugetlb_vmemmap_init(). This patch is actual enablement of the feature. There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct page structs that can be used when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP, so add a BUILD_BUG_ON to catch invalid usage of the tail struct page. Link: https://lkml.kernel.org/r/20210510030027.56044-10-songmuchun@bytedance.comSigned-off-by:
Oscar Salvador <osalvador@suse.de> Reviewed-by:
Chen Huang <chenhuang5@huawei.com> Tested-by:
Bodeddula Balasubramaniam <bodeddub@amazon.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by:
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Muchun Song authored
The parameter of memory_hotplug.memmap_on_memory is not compatible with hugetlb_free_vmemmap. So disable it when hugetlb_free_vmemmap is enabled. [akpm@linux-foundation.org: remove unneeded include, per Oscar] Link: https://lkml.kernel.org/r/20210510030027.56044-9-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
Add a kernel parameter hugetlb_free_vmemmap to enable the feature of freeing unused vmemmap pages associated with each hugetlb page on boot. We disable PMD mapping of vmemmap pages for x86-64 arch when this feature is enabled. Because vmemmap_remap_free() depends on vmemmap being base page mapped. Link: https://lkml.kernel.org/r/20210510030027.56044-8-songmuchun@bytedance.comSigned-off-by:
Barry Song <song.bao.hua@hisilicon.com> Reviewed-by:
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Muchun Song authored
When we free a HugeTLB page to the buddy allocator, we need to allocate the vmemmap pages associated with it. However, we may not be able to allocate the vmemmap pages when the system is under memory pressure. In this case, we just refuse to free the HugeTLB page. This changes behavior in some corner cases as listed below: 1) Failing to free a huge page triggered by the user (decrease nr_pages). User needs to try again later. 2) Failing to free a surplus huge page when freed by the application. Try again later when freeing a huge page next time. 3) Failing to dissolve a free huge page on ZONE_MOVABLE via offline_pages(). This can happen when we have plenty of ZONE_MOVABLE memory, but not enough kernel memory to allocate vmemmmap pages. We may even be able to migrate huge page contents, but will not be able to dissolve the source huge page. This will prevent an offline operation and is unfortunate as memory offlining is expected to succeed on movable zones. Users that depend on memory hotplug to succeed for movable zones should carefully consider whether the memory savings gained from this feature are worth the risk of possibly not being able to offline memory in certain situations. 4) Failing to dissolve a huge page on CMA/ZONE_MOVABLE via alloc_contig_range() - once we have that handling in place. Mainly affects CMA and virtio-mem. Similar to 3). virito-mem will handle migration errors gracefully. CMA might be able to fallback on other free areas within the CMA region. Vmemmap pages are allocated from the page freeing context. In order for those allocations to be not disruptive (e.g. trigger oom killer) __GFP_NORETRY is used. hugetlb_lock is dropped for the allocation because a non sleeping allocation would be too fragile and it could fail too easily under memory pressure. GFP_ATOMIC or other modes to access memory reserves is not used because we want to prevent consuming reserves under heavy hugetlb freeing. [mike.kravetz@oracle.com: fix dissolve_free_huge_page use of tail/head page] Link: https://lkml.kernel.org/r/20210527231225.226987-1-mike.kravetz@oracle.com [willy@infradead.org: fix alloc_vmemmap_page_list documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-6-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-7-songmuchun@bytedance.comSigned-off-by:Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by:
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Muchun Song authored
In the subsequent patch, we should allocate the vmemmap pages when freeing a HugeTLB page. But update_and_free_page() can be called under any context, so we cannot use GFP_KERNEL to allocate vmemmap pages. However, we can defer the actual freeing in a kworker to prevent from using GFP_ATOMIC to allocate the vmemmap pages. The __update_and_free_page() is where the call to allocate vmemmmap pages will be inserted. Link: https://lkml.kernel.org/r/20210510030027.56044-6-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
Every HugeTLB has more than one struct page structure. We __know__ that we only use the first 4 (__NR_USED_SUBPAGE) struct page structures to store metadata associated with each HugeTLB. There are a lot of struct page structures associated with each HugeTLB page. For tail pages, the value of compound_head is the same. So we can reuse first page of tail page structures. We map the virtual addresses of the remaining pages of tail page structures to the first tail page struct, and then free these page frames. Therefore, we need to reserve two pages as vmemmap areas. When we allocate a HugeTLB page from the buddy, we can free some vmemmap pages associated with each HugeTLB page. It is more appropriate to do it in the prep_new_huge_page(). The free_vmemmap_pages_per_hpage(), which indicates how many vmemmap pages associated with a HugeTLB page can be freed, returns zero for now, which means the feature is disabled. We will enable it once all the infrastructure is there. [willy@infradead.org: fix documentation warning] Link: https://lkml.kernel.org/r/20210615200242.1716568-5-willy@infradead.org Link: https://lkml.kernel.org/r/20210510030027.56044-5-songmuchun@bytedance.comSigned-off-by:
Michal Hocko <mhocko@suse.com> Reviewed-by:
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Muchun Song authored
For HugeTLB page, there are more metadata to save in the struct page. But the head struct page cannot meet our needs, so we have to abuse other tail struct page to store the metadata. In order to avoid conflicts caused by subsequent use of more tail struct pages, we can gather these discrete indexes of tail struct page. In this case, it will be easier to add a new tail page index later. Link: https://lkml.kernel.org/r/20210510030027.56044-4-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
The option HUGETLB_PAGE_FREE_VMEMMAP allows for the freeing of some vmemmap pages associated with pre-allocated HugeTLB pages. For example, on X86_64 6 vmemmap pages of size 4KB each can be saved for each 2MB HugeTLB page. 4094 vmemmap pages of size 4KB each can be saved for each 1GB HugeTLB page. When a HugeTLB page is allocated or freed, the vmemmap array representing the range associated with the page will need to be remapped. When a page is allocated, vmemmap pages are freed after remapping. When a page is freed, previously discarded vmemmap pages must be allocated before remapping. The config option is introduced early so that supporting code can be written to depend on the option. The initial version of the code only provides support for x86-64. If config HAVE_BOOTMEM_INFO_NODE is enabled, the freeing vmemmap page code denpend on it to free vmemmap pages. Otherwise, just use free_reserved_page() to free vmemmmap pages. The routine register_page_bootmem_info() is used to register bootmem info. Therefore, make sure register_page_bootmem_info is enabled if HUGETLB_PAGE_FREE_VMEMMAP is defined. Link: https://lkml.kernel.org/r/20210510030027.56044-3-songmuchun@bytedance.comSigned-off-by:
Balbir Singh <bsingharora@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: HORIGUCHI NAOYA <naoya.horiguchi@nec.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joao Martins <joao.m.martins@oracle.com> Cc: Joerg Roedel <jroedel@suse.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Oliver Neukum <oneukum@suse.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by:
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Muchun Song authored
Patch series "Free some vmemmap pages of HugeTLB page", v23. This patch series will free some vmemmap pages(struct page structures) associated with each HugeTLB page when preallocated to save memory. In order to reduce the difficulty of the first version of code review. In this version, we disable PMD/huge page mapping of vmemmap if this feature was enabled. This acutely eliminates a bunch of the complex code doing page table manipulation. When this patch series is solid, we cam add the code of vmemmap page table manipulation in the future. The struct page structures (page structs) are used to describe a physical page frame. By default, there is an one-to-one mapping from a page frame to it's corresponding page struct. The HugeTLB pages consist of multiple base page size pages and is supported by many architectures. See hugetlbpage.rst in the Documentation directory for more details. On the x86 architecture, HugeTLB pages of size 2MB and 1GB are currently supported. Since the base page size on x86 is 4KB, a 2MB HugeTLB page consists of 512 base pages and a 1GB HugeTLB page consists of 4096 base pages. For each base page, there is a corresponding page struct. Within the HugeTLB subsystem, only the first 4 page structs are used to contain unique information about a HugeTLB page. HUGETLB_CGROUP_MIN_ORDER provides this upper limit. The only 'useful' information in the remaining page structs is the compound_head field, and this field is the same for all tail pages. By removing redundant page structs for HugeTLB pages, memory can returned to the buddy allocator for other uses. When the system boot up, every 2M HugeTLB has 512 struct page structs which size is 8 pages(sizeof(struct page) * 512 / PAGE_SIZE). HugeTLB struct pages(8 pages) page frame(8 pages) +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ | | | 0 | -------------> | 0 | | | +-----------+ +-----------+ | | | 1 | -------------> | 1 | | | +-----------+ +-----------+ | | | 2 | -------------> | 2 | | | +-----------+ +-----------+ | | | 3 | -------------> | 3 | | | +-----------+ +-----------+ | | | 4 | -------------> | 4 | | 2MB | +-----------+ +-----------+ | | | 5 | -------------> | 5 | | | +-----------+ +-----------+ | | | 6 | -------------> | 6 | | | +-----------+ +-----------+ | | | 7 | -------------> | 7 | | | +-----------+ +-----------+ | | | | | | +-----------+ The value of page->compound_head is the same for all tail pages. The first page of page structs (page 0) associated with the HugeTLB page contains the 4 page structs necessary to describe the HugeTLB. The only use of the remaining pages of page structs (page 1 to page 7) is to point to page->compound_head. Therefore, we can remap pages 2 to 7 to page 1. Only 2 pages of page structs will be used for each HugeTLB page. This will allow us to free the remaining 6 pages to the buddy allocator. Here is how things look after remapping. HugeTLB struct pages(8 pages) page frame(8 pages) +-----------+ ---virt_to_page---> +-----------+ mapping to +-----------+ | | | 0 | -------------> | 0 | | | +-----------+ +-----------+ | | | 1 | -------------> | 1 | | | +-----------+ +-----------+ | | | 2 | ----------------^ ^ ^ ^ ^ ^ | | +-----------+ | | | | | | | | 3 | ------------------+ | | | | | | +-----------+ | | | | | | | 4 | --------------------+ | | | | 2MB | +-----------+ | | | | | | 5 | ----------------------+ | | | | +-----------+ | | | | | 6 | ------------------------+ | | | +-----------+ | | | | 7 | --------------------------+ | | +-----------+ | | | | | | +-----------+ When a HugeTLB is freed to the buddy system, we should allocate 6 pages for vmemmap pages and restore the previous mapping relationship. Apart from 2MB HugeTLB page, we also have 1GB HugeTLB page. It is similar to the 2MB HugeTLB page. We also can use this approach to free the vmemmap pages. In this case, for the 1GB HugeTLB page, we can save 4094 pages. This is a very substantial gain. On our server, run some SPDK/QEMU applications which will use 1024GB HugeTLB page. With this feature enabled, we can save ~16GB (1G hugepage)/~12GB (2MB hugepage) memory. Because there are vmemmap page tables reconstruction on the freeing/allocating path, it increases some overhead. Here are some overhead analysis. 1) Allocating 10240 2MB HugeTLB pages. a) With this patch series applied: # time echo 10240 > /proc/sys/vm/nr_hugepages real 0m0.166s user 0m0.000s sys 0m0.166s # bpftrace -e 'kprobe:alloc_fresh_huge_page { @start[tid] = nsecs; } kretprobe:alloc_fresh_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [8K, 16K) 5476 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [16K, 32K) 4760 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ | [32K, 64K) 4 | | b) Without this patch series: # time echo 10240 > /proc/sys/vm/nr_hugepages real 0m0.067s user 0m0.000s sys 0m0.067s # bpftrace -e 'kprobe:alloc_fresh_huge_page { @start[tid] = nsecs; } kretprobe:alloc_fresh_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [4K, 8K) 10147 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [8K, 16K) 93 | | Summarize: this feature is about ~2x slower than before. 2) Freeing 10240 2MB HugeTLB pages. a) With this patch series applied: # time echo 0 > /proc/sys/vm/nr_hugepages real 0m0.213s user 0m0.000s sys 0m0.213s # bpftrace -e 'kprobe:free_pool_huge_page { @start[tid] = nsecs; } kretprobe:free_pool_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [8K, 16K) 6 | | [16K, 32K) 10227 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [32K, 64K) 7 | | b) Without this patch series: # time echo 0 > /proc/sys/vm/nr_hugepages real 0m0.081s user 0m0.000s sys 0m0.081s # bpftrace -e 'kprobe:free_pool_huge_page { @start[tid] = nsecs; } kretprobe:free_pool_huge_page /@start[tid]/ { @latency = hist(nsecs - @start[tid]); delete(@start[tid]); }' Attaching 2 probes... @latency: [4K, 8K) 6805 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@| [8K, 16K) 3427 |@@@@@@@@@@@@@@@@@@@@@@@@@@ | [16K, 32K) 8 | | Summary: The overhead of __free_hugepage is about ~2-3x slower than before. Although the overhead has increased, the overhead is not significant. Like Mike said, "However, remember that the majority of use cases create HugeTLB pages at or shortly after boot time and add them to the pool. So, additional overhead is at pool creation time. There is no change to 'normal run time' operations of getting a page from or returning a page to the pool (think page fault/unmap)". Despite the overhead and in addition to the memory gains from this series. The following data is obtained by Joao Martins. Very thanks to his effort. There's an additional benefit which is page (un)pinners will see an improvement and Joao presumes because there are fewer memmap pages and thus the tail/head pages are staying in cache more often. Out of the box Joao saw (when comparing linux-next against linux-next + this series) with gup_test and pinning a 16G HugeTLB file (with 1G pages): get_user_pages(): ~32k -> ~9k unpin_user_pages(): ~75k -> ~70k Usually any tight loop fetching compound_head(), or reading tail pages data (e.g. compound_head) benefit a lot. There's some unpinning inefficiencies Joao was fixing[2], but with that in added it shows even more: unpin_user_pages(): ~27k -> ~3.8k [1] https://lore.kernel.org/linux-mm/20210409205254.242291-1-mike.kravetz@oracle.com/ [2] https://lore.kernel.org/linux-mm/20210204202500.26474-1-joao.m.martins@oracle.com/ This patch (of 9): Move bootmem info registration common API to individual bootmem_info.c. And we will use {get,put}_page_bootmem() to initialize the page for the vmemmap pages or free the vmemmap pages to buddy in the later patch. So move them out of CONFIG_MEMORY_HOTPLUG_SPARSE. This is just code movement without any functional change. Link: https://lkml.kernel.org/r/20210510030027.56044-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20210510030027.56044-2-songmuchun@bytedance.comSigned-off-by:
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- 29 Jun, 2021 14 commits
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Naoya Horiguchi authored
__get_hwpoison_page() could fail to grab refcount by some race condition, so it's helpful if we can handle it by retrying. We already have retry logic, so make get_hwpoison_page() call get_any_page() when called from memory_failure(). As a result, get_hwpoison_page() can return negative values (i.e. error code), so some callers are also changed to handle error cases. soft_offline_page() does nothing for -EBUSY because that's enough and users in userspace can easily handle it. unpoison_memory() is also unchanged because it's broken and need thorough fixes (will be done later). Link: https://lkml.kernel.org/r/20210603233632.2964832-3-nao.horiguchi@gmail.comSigned-off-by:
Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by:
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Naoya Horiguchi authored
Now an action required MCE in already hwpoisoned address surely sends a SIGBUS to current process, but the SIGBUS doesn't convey error virtual address. That's not optimal for hwpoison-aware applications. To fix the issue, make memory_failure() call kill_accessing_process(), that does pagetable walk to find the error virtual address. It could find multiple virtual addresses for the same error page, and it seems hard to tell which virtual address is correct one. But that's rare and sending incorrect virtual address could be better than no address. So let's report the first found virtual address for now. [naoya.horiguchi@nec.com: fix walk_page_range() return] Link: https://lkml.kernel.org/r/20210603051055.GA244241@hori.linux.bs1.fc.nec.co.jp Link: https://lkml.kernel.org/r/20210521030156.2612074-4-nao.horiguchi@gmail.comSigned-off-by:
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Mel Gorman authored
Dave Hansen reported the following about Feng Tang's tests on a machine with persistent memory onlined as a DRAM-like device. Feng Tang tossed these on a "Cascade Lake" system with 96 threads and ~512G of persistent memory and 128G of DRAM. The PMEM is in "volatile use" mode and being managed via the buddy just like the normal RAM. The PMEM zones are big ones: present 65011712 = 248 G high 134595 = 525 M The PMEM nodes, of course, don't have any CPUs in them. With your series, the pcp->high value per-cpu is 69584 pages or about 270MB per CPU. Scaled up by the 96 CPU threads, that's ~26GB of worst-case memory in the pcps per zone, or roughly 10% of the size of the zone. This should not cause a problem as such although it could trigger reclaim due to pages being stored on per-cpu lists for CPUs remote to a node. It is not possible to treat cpuless nodes exactly the same as normal nodes but the worst-case scenario can be mitigated by splitting pcp->high across all online CPUs for cpuless memory nodes. Link: https://lkml.kernel.org/r/20210616110743.GK30378@techsingularity.netSuggested-by:Dave Hansen <dave.hansen@intel.com> Signed-off-by:
Mel Gorman <mgorman@techsingularity.net> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Acked-by:
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Mel Gorman authored
The per-cpu page allocator (PCP) only stores order-0 pages. This means that all THP and "cheap" high-order allocations including SLUB contends on the zone->lock. This patch extends the PCP allocator to store THP and "cheap" high-order pages. Note that struct per_cpu_pages increases in size to 256 bytes (4 cache lines) on x86-64. Note that this is not necessarily a universal performance win because of how it is implemented. High-order pages can cause pcp->high to be exceeded prematurely for lower-orders so for example, a large number of THP pages being freed could release order-0 pages from the PCP lists. Hence, much depends on the allocation/free pattern as observed by a single CPU to determine if caching helps or hurts a particular workload. That said, basic performance testing passed. The following is a netperf UDP_STREAM test which hits the relevant patches as some of the network allocations are high-order. netperf-udp 5.13.0-rc2 5.13.0-rc2 mm-pcpburst-v3r4 mm-pcphighorder-v1r7 Hmean send-64 261.46 ( 0.00%) 266.30 * 1.85%* Hmean send-128 516.35 ( 0.00%) 536.78 * 3.96%* Hmean send-256 1014.13 ( 0.00%) 1034.63 * 2.02%* Hmean send-1024 3907.65 ( 0.00%) 4046.11 * 3.54%* Hmean send-2048 7492.93 ( 0.00%) 7754.85 * 3.50%* Hmean send-3312 11410.04 ( 0.00%) 11772.32 * 3.18%* Hmean send-4096 13521.95 ( 0.00%) 13912.34 * 2.89%* Hmean send-8192 21660.50 ( 0.00%) 22730.72 * 4.94%* Hmean send-16384 31902.32 ( 0.00%) 32637.50 * 2.30%* Functionally, a patch like this is necessary to make bulk allocation of high-order pages work with similar performance to order-0 bulk allocations. The bulk allocator is not updated in this series as it would have to be determined by bulk allocation users how they want to track the order of pages allocated with the bulk allocator. Link: https://lkml.kernel.org/r/20210611135753.GC30378@techsingularity.netSigned-off-by: -
Mike Rapoport authored
After removal of the DISCONTIGMEM memory model the FLAT_NODE_MEM_MAP configuration option is equivalent to FLATMEM. Drop CONFIG_FLAT_NODE_MEM_MAP and use CONFIG_FLATMEM instead. Link: https://lkml.kernel.org/r/20210608091316.3622-10-rppt@kernel.orgSigned-off-by:
Mike Rapoport <rppt@linux.ibm.com> Acked-by:
Arnd Bergmann <arnd@arndb.de> Acked-by:
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Mike Rapoport authored
After removal of DISCINTIGMEM the NEED_MULTIPLE_NODES and NUMA configuration options are equivalent. Drop CONFIG_NEED_MULTIPLE_NODES and use CONFIG_NUMA instead. Done with $ sed -i 's/CONFIG_NEED_MULTIPLE_NODES/CONFIG_NUMA/' \ $(git grep -wl CONFIG_NEED_MULTIPLE_NODES) $ sed -i 's/NEED_MULTIPLE_NODES/NUMA/' \ $(git grep -wl NEED_MULTIPLE_NODES) with manual tweaks afterwards. [rppt@linux.ibm.com: fix arm boot crash] Link: https://lkml.kernel.org/r/YMj9vHhHOiCVN4BF@linux.ibm.com Link: https://lkml.kernel.org/r/20210608091316.3622-9-rppt@kernel.orgSigned-off-by:
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Mike Rapoport authored
Remove description of DISCONTIGMEM from the "Memory Models" document and update VM sysctl description so that it won't mention DISCONIGMEM. Link: https://lkml.kernel.org/r/20210608091316.3622-8-rppt@kernel.orgSigned-off-by:
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Mike Rapoport authored
There are several places that mention DISCONIGMEM in comments or have stale code guarded by CONFIG_DISCONTIGMEM. Remove the dead code and update the comments. Link: https://lkml.kernel.org/r/20210608091316.3622-7-rppt@kernel.orgSigned-off-by:
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Mike Rapoport authored
There are no architectures that support DISCONTIGMEM left. Remove the configuration option and the dead code it was guarding in the generic memory management code. Link: https://lkml.kernel.org/r/20210608091316.3622-6-rppt@kernel.orgSigned-off-by:
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Mike Rapoport authored
DISCONTIGMEM was replaced by FLATMEM with freeing of the unused memory map in v5.11. Remove the support for DISCONTIGMEM entirely. Link: https://lkml.kernel.org/r/20210608091316.3622-5-rppt@kernel.orgSigned-off-by:
Geert Uytterhoeven <geert@linux-m68k.org> Acked-by:
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Mike Rapoport authored
DISCONTIGMEM was replaced by FLATMEM with freeing of the unused memory map in v5.11. Remove the support for DISCONTIGMEM entirely. Link: https://lkml.kernel.org/r/20210608091316.3622-4-rppt@kernel.orgSigned-off-by:
Vineet Gupta <vgupta@synopsys.com> Acked-by:
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Mike Rapoport authored
Arc does not use DISCONTIGMEM to implement high memory, update the comment describing how high memory works to reflect this. Link: https://lkml.kernel.org/r/20210608091316.3622-3-rppt@kernel.orgSigned-off-by:
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Mike Rapoport authored
Patch series "Remove DISCONTIGMEM memory model", v3. SPARSEMEM memory model was supposed to entirely replace DISCONTIGMEM a (long) while ago. The last architectures that used DISCONTIGMEM were updated to use other memory models in v5.11 and it is about the time to entirely remove DISCONTIGMEM from the kernel. This set removes DISCONTIGMEM from alpha, arc and m68k, simplifies memory model selection in mm/Kconfig and replaces usage of redundant CONFIG_NEED_MULTIPLE_NODES and CONFIG_FLAT_NODE_MEM_MAP with CONFIG_NUMA and CONFIG_FLATMEM respectively. I've also removed NUMA support on alpha that was BROKEN for more than 15 years. There were also minor updates all over arch/ to remove mentions of DISCONTIGMEM in comments and #ifdefs. This patch (of 9): NUMA is marked broken on alpha for more than 15 years and DISCONTIGMEM was replaced with SPARSEMEM in v5.11. Remove both NUMA and DISCONTIGMEM support from alpha. Link: https://lkml.kernel.org/r/20210608091316.3622-1-rppt@kernel.org Link: https://lkml.kernel.org/r/20210608091316.3622-2-rppt@kernel.orgSigned-off-by:
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Mel Gorman authored
Patch series "Allow high order pages to be stored on PCP", v2. The per-cpu page allocator (PCP) only handles order-0 pages. With the series "Use local_lock for pcp protection and reduce stat overhead" and "Calculate pcp->high based on zone sizes and active CPUs", it's now feasible to store high-order pages on PCP lists. This small series allows PCP to store "cheap" orders where cheap is determined by PAGE_ALLOC_COSTLY_ORDER and THP-sized allocations. This patch (of 2): In the next page, free_compount_page is going to use the common helper free_the_page. This patch moves the definition to ease review. No functional change. Link: https://lkml.kernel.org/r/20210603142220.10851-1-mgorman@techsingularity.net Link: https://lkml.kernel.org/r/20210603142220.10851-2-mgorman@techsingularity.netSigned-off-by:
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