From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f51.google.com (mail-ej1-f51.google.com [209.85.218.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E58D2586F3; Wed, 12 Feb 2025 17:04:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739379889; cv=none; b=d5m4SndL5UvnxvPey4j0pwgshy0pLtYsEvTOe5ph7VGBng1ovlLTnHz16xpJfS2asACnRGZhHEhXS8HuYIabhSO0O2/ai1DknELJAQEKz4S7DyyvBotMuYivZJbNxEH00/llVg5BmEd1tI7lqwg9hProHww49EUAPgzT0jcfIcc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739379889; c=relaxed/simple; bh=jMfdTRsZdI5eWoj3aWSlH0xyFaWuq8yWsFhqFzD+kCc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jsKxjLsJ8r83jErh9ONJKloXu0V4tJANT5cr3ZKC5XhsiPsIN3PGQ7IcTdiihz6R9DXWe5KnmeARK4ynBMwiCY1RGhuisRRUZ1sOPqtKci/k/qdu1JdJMMVJBfsLYEjR/hFdbXW12FaOlodf47TFmi/38lOBIrBX6iMHOttOctc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=IPELDo8X; arc=none smtp.client-ip=209.85.218.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IPELDo8X" Received: by mail-ej1-f51.google.com with SMTP id a640c23a62f3a-ab7430e27b2so1342379066b.3; Wed, 12 Feb 2025 09:04:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1739379885; x=1739984685; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=Fvzxk7wvgu91bGu3wJDWmHVE0pCbZmsOLUpuRRBS1Oo=; b=IPELDo8XCybDA94V3dqMxxlUG5PogtTcAxE5A23UUKckRH51ZAerPO7T2L7GDb/hBk V7RNyAcgC/FU8STPfPOTieyDEsuja9yQH/Ds23dO9YbcaSDyhAd8sVoXz/0hxSkymwkq RUKEzOHexDUqiLye4f1J0utFHAfpD5rt0eXKlUTCBLfefBhyxL25IArE+QUBfx/jZOAQ Cytu+yku9rkS3os25seC78MjTRlYJRbFNMxtE4r+q4QbDGXGENOcU2oy8UKh/t/mDchj C4zB3j0qii8q/ApruEXptJHKSceVZY1z4z1nJoC9LZeUiALE3WBAF3fbH4M0NMVdYOJO eYwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1739379885; x=1739984685; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Fvzxk7wvgu91bGu3wJDWmHVE0pCbZmsOLUpuRRBS1Oo=; b=bHPHd1OHwCguyTmjIigYhDt3r94l7nqUlRDWWLHNrPHz96RwirG8PdXL/Fw1H+JtW1 Wj6KP7BdiL5K7/+KHPtqAypVuHql96fX0siHla5PttKeBmZqWNJZu/hH68il6HE7tqen 4ELwwmv6gPJwcRAH3Yvmtti7tIaBypmLsg1b3O5s7BTXw2/fP9gpM0FpjOY9iHo5/HJ6 mMjWIkjLTMNPHJz8t6+1NIuNB45c5SPiHHIO7eyf5B5VKRDBVML98wgvaeS+CTB8fmzd 6q39dZDYqMWQjXO/FRF0j0/lUCqULP++5QQs/4kv0CHTardTezE/waDtkN8hwNX+JeXv WO4A== X-Forwarded-Encrypted: i=1; AJvYcCWsAmbEId9UKqByC+SnAHHZ/Tcy8YYONyieoTy/c2Xyeyk0BASSpc7lhA1u3kPUW4IzcLPOwJZ7JapzQiM=@vger.kernel.org, AJvYcCXcsMrciMfzKEAe/2cpa6NntZLEuEzaBv7etVqYHB6OErhA0BI/3Y8FXXG5LNECTlZAnECkO4/mZ1511KLK1+mtsWWo@vger.kernel.org X-Gm-Message-State: AOJu0YxmbPv4jJYlKZXh/JFcBct9yLX41THjXW1cuJPFdq9D30dTaMlC Fjl8jxW+8hL1uc1wLDNwPf4+8FmH22CnOrhZaYos2WqstDlvCWlx X-Gm-Gg: ASbGncu/+TP0F7TW+l7OvCmLll6XDWWngXPIAOtPeE+FOX+7A6P1+bTAt9dnm4J1EKo 3HZo9k9Bp7FL5Jflv9+jiSL1dmcgP/7IfD7HbgmeqkMQBf6pCMV8SXuWYce6RFGMVTAuWEPnvu8 yxkMGRnIhaOO8RPrlCmPISHDEt27zwuZLsreXOmIa0VVf+KexCbb78u3aT18mkFhRBqSa9X0UQJ vqiS1rsm0alRAlUo55GvmbMhMJm2h6Tq+J7QyrMU69lgdi9J3j6ANYsLVTLkM0yBk6atBVQq3zC 8oORm9QL/Ll5MvQc8geXpaBctVpVIbFno16sSb3mN4kiGDxPSePHMKRrZr2fHQ== X-Google-Smtp-Source: AGHT+IG7q/wYJM73PiW8r3OsiQSf89b8XBujhBqSp6Ld1tSLhvrTp1ylssyeX8E7sgzOgoQUiPkV8Q== X-Received: by 2002:a17:907:d17:b0:ab7:9df1:e562 with SMTP id a640c23a62f3a-ab7f34d3323mr317980366b.48.1739379884809; Wed, 12 Feb 2025 09:04:44 -0800 (PST) Received: from ?IPV6:2a03:83e0:1126:4:fb:39c9:9a24:d181? ([2620:10d:c092:500::6:8e63]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ab78e3e212dsm1136599566b.147.2025.02.12.09.04.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Feb 2025 09:04:44 -0800 (PST) Message-ID: <9ade1f26-1642-48b3-b7e4-ba571892c7d6@gmail.com> Date: Wed, 12 Feb 2025 17:04:43 +0000 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v2 7/9] khugepaged: add mTHP support To: Nico Pache , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org Cc: ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, srivatsa@csail.mit.edu, haowenchao22@gmail.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, jglisse@google.com, surenb@google.com, vishal.moola@gmail.com, zokeefe@google.com, zhengqi.arch@bytedance.com, jhubbard@nvidia.com, 21cnbao@gmail.com, willy@infradead.org, kirill.shutemov@linux.intel.com, david@redhat.com, aarcange@redhat.com, raquini@redhat.com, dev.jain@arm.com, sunnanyong@huawei.com, audra@redhat.com, akpm@linux-foundation.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, tiwai@suse.de, Johannes Weiner References: <20250211003028.213461-1-npache@redhat.com> <20250211003028.213461-8-npache@redhat.com> Content-Language: en-US From: Usama Arif In-Reply-To: <20250211003028.213461-8-npache@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/02/2025 00:30, Nico Pache wrote: > Introduce the ability for khugepaged to collapse to different mTHP sizes. > While scanning a PMD range for potential collapse candidates, keep track > of pages in MIN_MTHP_ORDER chunks via a bitmap. Each bit represents a > utilized region of order MIN_MTHP_ORDER ptes. We remove the restriction > of max_ptes_none during the scan phase so we dont bailout early and miss > potential mTHP candidates. > > After the scan is complete we will perform binary recursion on the > bitmap to determine which mTHP size would be most efficient to collapse > to. max_ptes_none will be scaled by the attempted collapse order to > determine how full a THP must be to be eligible. > > If a mTHP collapse is attempted, but contains swapped out, or shared > pages, we dont perform the collapse. > > Signed-off-by: Nico Pache > --- > mm/khugepaged.c | 122 ++++++++++++++++++++++++++++++++---------------- > 1 file changed, 83 insertions(+), 39 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index c8048d9ec7fb..cd310989725b 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1127,13 +1127,14 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > { > LIST_HEAD(compound_pagelist); > pmd_t *pmd, _pmd; > - pte_t *pte; > + pte_t *pte, mthp_pte; > pgtable_t pgtable; > struct folio *folio; > spinlock_t *pmd_ptl, *pte_ptl; > int result = SCAN_FAIL; > struct vm_area_struct *vma; > struct mmu_notifier_range range; > + unsigned long _address = address + offset * PAGE_SIZE; > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > > /* > @@ -1148,12 +1149,13 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > *mmap_locked = false; > } > > - result = alloc_charge_folio(&folio, mm, cc, HPAGE_PMD_ORDER); > + result = alloc_charge_folio(&folio, mm, cc, order); > if (result != SCAN_SUCCEED) > goto out_nolock; > > mmap_read_lock(mm); > - result = hugepage_vma_revalidate(mm, address, true, &vma, cc, HPAGE_PMD_ORDER); > + *mmap_locked = true; > + result = hugepage_vma_revalidate(mm, address, true, &vma, cc, order); > if (result != SCAN_SUCCEED) { > mmap_read_unlock(mm); > goto out_nolock; > @@ -1171,13 +1173,14 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > * released when it fails. So we jump out_nolock directly in > * that case. Continuing to collapse causes inconsistency. > */ > - result = __collapse_huge_page_swapin(mm, vma, address, pmd, > - referenced, HPAGE_PMD_ORDER); > + result = __collapse_huge_page_swapin(mm, vma, _address, pmd, > + referenced, order); > if (result != SCAN_SUCCEED) > goto out_nolock; > } > > mmap_read_unlock(mm); > + *mmap_locked = false; > /* > * Prevent all access to pagetables with the exception of > * gup_fast later handled by the ptep_clear_flush and the VM > @@ -1187,7 +1190,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > * mmap_lock. > */ > mmap_write_lock(mm); > - result = hugepage_vma_revalidate(mm, address, true, &vma, cc, HPAGE_PMD_ORDER); > + result = hugepage_vma_revalidate(mm, address, true, &vma, cc, order); > if (result != SCAN_SUCCEED) > goto out_up_write; > /* check if the pmd is still valid */ > @@ -1198,11 +1201,12 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > vma_start_write(vma); > anon_vma_lock_write(vma->anon_vma); > > - mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, address, > - address + HPAGE_PMD_SIZE); > + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, _address, > + _address + (PAGE_SIZE << order)); > mmu_notifier_invalidate_range_start(&range); > > pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */ > + > /* > * This removes any huge TLB entry from the CPU so we won't allow > * huge and small TLB entries for the same virtual address to > @@ -1216,10 +1220,10 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > mmu_notifier_invalidate_range_end(&range); > tlb_remove_table_sync_one(); > > - pte = pte_offset_map_lock(mm, &_pmd, address, &pte_ptl); > + pte = pte_offset_map_lock(mm, &_pmd, _address, &pte_ptl); > if (pte) { > - result = __collapse_huge_page_isolate(vma, address, pte, cc, > - &compound_pagelist, HPAGE_PMD_ORDER); > + result = __collapse_huge_page_isolate(vma, _address, pte, cc, > + &compound_pagelist, order); > spin_unlock(pte_ptl); > } else { > result = SCAN_PMD_NULL; > @@ -1248,8 +1252,8 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > anon_vma_unlock_write(vma->anon_vma); > > result = __collapse_huge_page_copy(pte, folio, pmd, _pmd, > - vma, address, pte_ptl, > - &compound_pagelist, HPAGE_PMD_ORDER); > + vma, _address, pte_ptl, > + &compound_pagelist, order); > pte_unmap(pte); > if (unlikely(result != SCAN_SUCCEED)) > goto out_up_write; > @@ -1260,20 +1264,37 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, > * write. > */ > __folio_mark_uptodate(folio); > - pgtable = pmd_pgtable(_pmd); > - > - _pmd = mk_huge_pmd(&folio->page, vma->vm_page_prot); > - _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); > - > - spin_lock(pmd_ptl); > - BUG_ON(!pmd_none(*pmd)); > - folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE); > - folio_add_lru_vma(folio, vma); > - pgtable_trans_huge_deposit(mm, pmd, pgtable); > - set_pmd_at(mm, address, pmd, _pmd); > - update_mmu_cache_pmd(vma, address, pmd); > - deferred_split_folio(folio, false); > - spin_unlock(pmd_ptl); > + if (order == HPAGE_PMD_ORDER) { > + pgtable = pmd_pgtable(_pmd); > + _pmd = mk_huge_pmd(&folio->page, vma->vm_page_prot); > + _pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma); > + > + spin_lock(pmd_ptl); > + BUG_ON(!pmd_none(*pmd)); > + folio_add_new_anon_rmap(folio, vma, _address, RMAP_EXCLUSIVE); > + folio_add_lru_vma(folio, vma); > + pgtable_trans_huge_deposit(mm, pmd, pgtable); > + set_pmd_at(mm, address, pmd, _pmd); > + update_mmu_cache_pmd(vma, address, pmd); > + deferred_split_folio(folio, false); > + spin_unlock(pmd_ptl); > + } else { //mTHP > + mthp_pte = mk_pte(&folio->page, vma->vm_page_prot); > + mthp_pte = maybe_mkwrite(pte_mkdirty(mthp_pte), vma); > + > + spin_lock(pmd_ptl); > + folio_ref_add(folio, (1 << order) - 1); > + folio_add_new_anon_rmap(folio, vma, _address, RMAP_EXCLUSIVE); > + folio_add_lru_vma(folio, vma); > + spin_lock(pte_ptl); > + set_ptes(vma->vm_mm, _address, pte, mthp_pte, (1 << order)); > + update_mmu_cache_range(NULL, vma, _address, pte, (1 << order)); > + spin_unlock(pte_ptl); > + smp_wmb(); /* make pte visible before pmd */ > + pmd_populate(mm, pmd, pmd_pgtable(_pmd)); > + deferred_split_folio(folio, false); Hi Nico, This patch will have the same issue as the one I pointed out in https://lore.kernel.org/all/82b9efd1-f2a6-4452-b2ea-6c163e17cdf7@gmail.com/ ?