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Mon, 14 Apr 2025 22:07:15 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.64.91]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id DFA311955BC1; Mon, 14 Apr 2025 22:07:07 +0000 (UTC) From: Nico Pache To: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, david@redhat.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, ryan.roberts@arm.com, willy@infradead.org, peterx@redhat.com, ziy@nvidia.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kirill.shutemov@linux.intel.com, aarcange@redhat.com, raquini@redhat.com, dev.jain@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com Subject: [PATCH v3 05/12] khugepaged: generalize __collapse_huge_page_* for mTHP support Date: Mon, 14 Apr 2025 16:05:50 -0600 Message-ID: <20250414220557.35388-6-npache@redhat.com> In-Reply-To: <20250414220557.35388-1-npache@redhat.com> References: <20250414220557.35388-1-npache@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Rspamd-Queue-Id: D4ED340009 X-Stat-Signature: epnqf3g8eydhf4aexg4nwsa5b34tgpqd X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1744668446-32591 X-HE-Meta: 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 VaV31Ws+ 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 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: List-Subscribe: List-Unsubscribe: generalize the order of the __collapse_huge_page_* functions to support future mTHP collapse. mTHP collapse can suffer from incosistant behavior, and memory waste "creep". disable swapin and shared support for mTHP collapse. No functional changes in this patch. Co-developed-by: Dev Jain Signed-off-by: Dev Jain Signed-off-by: Nico Pache --- mm/khugepaged.c | 46 ++++++++++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 18 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 78caa6d227c3..dfecedc6a515 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -565,15 +565,17 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, unsigned long address, pte_t *pte, struct collapse_control *cc, - struct list_head *compound_pagelist) + struct list_head *compound_pagelist, + u8 order) { struct page *page = NULL; struct folio *folio = NULL; pte_t *_pte; int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0; bool writable = false; + int scaled_none = khugepaged_max_ptes_none >> (HPAGE_PMD_ORDER - order); - for (_pte = pte; _pte < pte + HPAGE_PMD_NR; + for (_pte = pte; _pte < pte + (1 << order); _pte++, address += PAGE_SIZE) { pte_t pteval = ptep_get(_pte); if (pte_none(pteval) || (pte_present(pteval) && @@ -581,7 +583,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, ++none_or_zero; if (!userfaultfd_armed(vma) && (!cc->is_khugepaged || - none_or_zero <= khugepaged_max_ptes_none)) { + none_or_zero <= scaled_none)) { continue; } else { result = SCAN_EXCEED_NONE_PTE; @@ -609,8 +611,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma, /* See hpage_collapse_scan_pmd(). */ if (folio_maybe_mapped_shared(folio)) { ++shared; - if (cc->is_khugepaged && - shared > khugepaged_max_ptes_shared) { + if (order != HPAGE_PMD_ORDER || (cc->is_khugepaged && + shared > khugepaged_max_ptes_shared)) { result = SCAN_EXCEED_SHARED_PTE; count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); goto out; @@ -711,13 +713,14 @@ static void __collapse_huge_page_copy_succeeded(pte_t *pte, struct vm_area_struct *vma, unsigned long address, spinlock_t *ptl, - struct list_head *compound_pagelist) + struct list_head *compound_pagelist, + u8 order) { struct folio *src, *tmp; pte_t *_pte; pte_t pteval; - for (_pte = pte; _pte < pte + HPAGE_PMD_NR; + for (_pte = pte; _pte < pte + (1 << order); _pte++, address += PAGE_SIZE) { pteval = ptep_get(_pte); if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { @@ -764,7 +767,8 @@ static void __collapse_huge_page_copy_failed(pte_t *pte, pmd_t *pmd, pmd_t orig_pmd, struct vm_area_struct *vma, - struct list_head *compound_pagelist) + struct list_head *compound_pagelist, + u8 order) { spinlock_t *pmd_ptl; @@ -781,7 +785,7 @@ static void __collapse_huge_page_copy_failed(pte_t *pte, * Release both raw and compound pages isolated * in __collapse_huge_page_isolate. */ - release_pte_pages(pte, pte + HPAGE_PMD_NR, compound_pagelist); + release_pte_pages(pte, pte + (1 << order), compound_pagelist); } /* @@ -802,7 +806,7 @@ static void __collapse_huge_page_copy_failed(pte_t *pte, static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio, pmd_t *pmd, pmd_t orig_pmd, struct vm_area_struct *vma, unsigned long address, spinlock_t *ptl, - struct list_head *compound_pagelist) + struct list_head *compound_pagelist, u8 order) { unsigned int i; int result = SCAN_SUCCEED; @@ -810,7 +814,7 @@ static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio, /* * Copying pages' contents is subject to memory poison at any iteration. */ - for (i = 0; i < HPAGE_PMD_NR; i++) { + for (i = 0; i < (1 << order); i++) { pte_t pteval = ptep_get(pte + i); struct page *page = folio_page(folio, i); unsigned long src_addr = address + i * PAGE_SIZE; @@ -829,10 +833,10 @@ static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio, if (likely(result == SCAN_SUCCEED)) __collapse_huge_page_copy_succeeded(pte, vma, address, ptl, - compound_pagelist); + compound_pagelist, order); else __collapse_huge_page_copy_failed(pte, pmd, orig_pmd, vma, - compound_pagelist); + compound_pagelist, order); return result; } @@ -1000,11 +1004,11 @@ static int check_pmd_still_valid(struct mm_struct *mm, static int __collapse_huge_page_swapin(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, - int referenced) + int referenced, u8 order) { int swapped_in = 0; vm_fault_t ret = 0; - unsigned long address, end = haddr + (HPAGE_PMD_NR * PAGE_SIZE); + unsigned long address, end = haddr + (PAGE_SIZE << order); int result; pte_t *pte = NULL; spinlock_t *ptl; @@ -1035,6 +1039,12 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm, if (!is_swap_pte(vmf.orig_pte)) continue; + /* Dont swapin for mTHP collapse */ + if (order != HPAGE_PMD_ORDER) { + result = SCAN_EXCEED_SWAP_PTE; + goto out; + } + vmf.pte = pte; vmf.ptl = ptl; ret = do_swap_page(&vmf); @@ -1154,7 +1164,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, * that case. Continuing to collapse causes inconsistency. */ result = __collapse_huge_page_swapin(mm, vma, address, pmd, - referenced); + referenced, HPAGE_PMD_ORDER); if (result != SCAN_SUCCEED) goto out_nolock; } @@ -1201,7 +1211,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, pte = pte_offset_map_lock(mm, &_pmd, address, &pte_ptl); if (pte) { result = __collapse_huge_page_isolate(vma, address, pte, cc, - &compound_pagelist); + &compound_pagelist, HPAGE_PMD_ORDER); spin_unlock(pte_ptl); } else { result = SCAN_PMD_NULL; @@ -1231,7 +1241,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, result = __collapse_huge_page_copy(pte, folio, pmd, _pmd, vma, address, pte_ptl, - &compound_pagelist); + &compound_pagelist, HPAGE_PMD_ORDER); pte_unmap(pte); if (unlikely(result != SCAN_SUCCEED)) goto out_up_write;