From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D840710D14A4 for ; Mon, 30 Mar 2026 11:57:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4EC046B009D; Mon, 30 Mar 2026 07:57:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49C5A6B009E; Mon, 30 Mar 2026 07:57:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 33D666B009F; Mon, 30 Mar 2026 07:57:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 1C0BF6B009D for ; Mon, 30 Mar 2026 07:57:01 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B95B813B329 for ; Mon, 30 Mar 2026 11:57:00 +0000 (UTC) X-FDA: 84602578200.12.0FDA19D Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf16.hostedemail.com (Postfix) with ESMTP id 983E0180009 for ; Mon, 30 Mar 2026 11:56:58 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="Wl0/02Vq"; spf=pass (imf16.hostedemail.com: domain of mpenttil@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mpenttil@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774871818; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=gOw0QU9Oof9RocPvQ9KEFP3H8j2F9DuWheKeh6hVYYU=; b=ZAGlyyOKshbAxIAeQ9OqXHuFRYxmyxVNsaQfeWrTJP/ACPAc2FXob4RxBr4hfkP+9up3lL NdPbRNd6IkfG9vKK6oFRFOxghGoNsVimew/Nazh8DiWlkmouvgiVKjz53safnKC3uoVQeJ hSA+ubRA3SAJOqkf1I0TFMITdbUJmD8= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="Wl0/02Vq"; spf=pass (imf16.hostedemail.com: domain of mpenttil@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=mpenttil@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774871818; a=rsa-sha256; cv=none; b=RmaLUqDswcQoR2R71pMsuMf8IB5F+OUXfMGLA9+duVj/KZUQAl84NOjYl7m/SU+SIV/j2N 14IKMLqyXPC7PdcqWWdw7VFo+imPLWv0Se0ysxG05vjhDHNKiY5XEroMs57ZBUukq4xcIk 9xSHal5IZnwXs5LFzY69ykFlov5R7Hs= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774871818; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gOw0QU9Oof9RocPvQ9KEFP3H8j2F9DuWheKeh6hVYYU=; b=Wl0/02VqE2K4sNsKWuscmARyikfkHw+sSGAos+4plrKDbP4I/daxEKmRShJwOW3gfuaOXs toiylIYcMM1mDUTstTakviFvi/wIcV88L23An+ghR5l4aoYpKWhprXHaIsWYUHumWrROp9 891xFJmbaQkWdTqmIzDHFkwlscdL56M= Received: from mail-lj1-f197.google.com (mail-lj1-f197.google.com [209.85.208.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-81-dhU3LDZBMcatinLSJ0T4GQ-1; Mon, 30 Mar 2026 07:56:56 -0400 X-MC-Unique: dhU3LDZBMcatinLSJ0T4GQ-1 X-Mimecast-MFC-AGG-ID: dhU3LDZBMcatinLSJ0T4GQ_1774871815 Received: by mail-lj1-f197.google.com with SMTP id 38308e7fff4ca-38c22faefe4so15746901fa.2 for ; Mon, 30 Mar 2026 04:56:56 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774871814; x=1775476614; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=gOw0QU9Oof9RocPvQ9KEFP3H8j2F9DuWheKeh6hVYYU=; b=ReeBDIj7fnO4Fud44eySP+1IoPjwOt23jGreCHKXIoqNuk0ZM1r6g+LhjkZ1aHkVMx KIyKVPBsEmW8SiHmQYVFm60jP0T7arZTPcnVrnUlMD/furDAXsOx2Wdp08r0QEixQcjv R6pMn/vPAR5R+qVRaT1nc5ovBT0stR83/yjq9s0hoxi3F40dIHCFTwT4m4JBqBpRGd3i VEmnYk2m3jfILGfadr8iA1JfsQ+ZFtloBV66Y0z1Yhjwe8V01MgVihJwEemR1/eivlmI j6mMsA3zub2I1ZK36ZyuEv9JUtPU92ZROJjdDo/kIUXdYmRLmZSszWuoShGDo9E9VdIf gMVw== X-Gm-Message-State: AOJu0Yz3qWwJXX7HPzrIFLG7vcK0OKcG/GPxN9TvmNI5L8Ww65J7TMZ3 0BG+SGWe5dMAPn3djxTfw/HqAPQUImRCy8MT55EX8MRvrSI16GUDibgpAEmJ+FugncJSLQV+1fp HSeFudCnYBzhQomfJ4jxgOuJKpDIhDX7p4BYftoDJzhtfT8QVeIx8K7OMEoBcMnofcqNVzZMWZC PMy2tthAeKq+Y4GAGVs10XwmLvm1hWiqVoNVtRQw== X-Gm-Gg: ATEYQzxG0cqxBZSwMybhm9GDDEyVKtTuaKIiAClpiQY/eEpMV51mpQPjBpsJF6ne39K wb5BypLnYMsVfid4CzZfAI02RHUv9/YDSfICBXMWARWhuTJWzjC42++5zYIU9jgRA9eea+tZW5m nYu72E/4Z7Tyrj2wa9dbSAIVYFRJHwDVigJhxPF8Z6sOnG7Pfu1tadbm81YhNPlWPk1dTCDP1nM G/Z0LNcGPKd9VfIT0B8HryCvYdUMgpKKzf+DtpJfm4F14KvFup3YQkQ6Xf7wP3SLyRzlaAstMP5 kl4Y2rtSDdFJn2BFubYOySXBoEKTWDMv2Zn1xRsM/mrBhiHertuOhKFQHNtFKf7S3k1MacDTLZU LYINBL+idUrhHCKAOshjOU8arP9yPiM6x+dUE X-Received: by 2002:a2e:ab0f:0:b0:38c:63a9:7522 with SMTP id 38308e7fff4ca-38c73273b5emr35137661fa.23.1774871814423; Mon, 30 Mar 2026 04:56:54 -0700 (PDT) X-Received: by 2002:a2e:ab0f:0:b0:38c:63a9:7522 with SMTP id 38308e7fff4ca-38c73273b5emr35137371fa.23.1774871813703; Mon, 30 Mar 2026 04:56:53 -0700 (PDT) Received: from fedora (85-23-51-1.bb.dnainternet.fi. [85.23.51.1]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-38c838daa4bsm16330071fa.32.2026.03.30.04.56.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Mar 2026 04:56:52 -0700 (PDT) From: mpenttil@redhat.com To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, =?UTF-8?q?Mika=20Penttil=C3=A4?= , David Hildenbrand , Jason Gunthorpe , Leon Romanovsky , Alistair Popple , Balbir Singh , Zi Yan , Matthew Brost Subject: [PATCH v7 4/6] mm: setup device page migration in HMM pagewalk Date: Mon, 30 Mar 2026 14:56:09 +0300 Message-ID: <20260330115611.347988-5-mpenttil@redhat.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20260330115611.347988-1-mpenttil@redhat.com> References: <20260330115611.347988-1-mpenttil@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 40CmWsmG1JQZSaoxf9-q0gPVQv9cHL64JWmjWQHV4ic_1774871815 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 983E0180009 X-Stat-Signature: 84bgmoif7se751iarfttpyxt19qa33uo X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1774871818-161793 X-HE-Meta: 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 t0bG8C/s oglJxD6OCPd7XVlOAcchbRlXO+hLj4jhk1rT+lGXbgXFs/plEYxiW+l2VSYCadlf/g7cDm0ziAmfz1X1qbFhYmRb/FVfq/xNDMdRhtm/uAfuE4hJD3RkxWTB+NpwrRz3lVUVS/VGfj27qSHeqE+i3m8/k95woAEyoLUKNFiyPn4tTzZi1ns2cH7ZGVnRhYOecWz+CU8HOQDYVgAe0RYrBsmp3zUnzhCETB72KkwtgLIbQDo/4hOoeo6rNAAfHLtbiuiuSbsyg1q/i1BMhjYS3Ka0jEJpys17P8HhSuqn0SDtxOsD5rVQakGJ6omZamw9H9xnMDxchFidTLgB2PC+f3J27OxXMZUnekmgOL0xffzgLde/faG5pstYbDVQ9EDrmMV+GLhd06PNDXPQQQd7AQ+15aGgQNbGBR+RT Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Mika Penttilä Implement the needed hmm_vma_handle_migrate_prepare_pmd() and hmm_vma_handle_migrate_prepare() functions which are mostly carried over from migrate_device.c, as well as the needed split functions. Make migrate_device take use of HMM pagewalk for collecting part of migration. Cc: David Hildenbrand Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Alistair Popple Cc: Balbir Singh Cc: Zi Yan Cc: Matthew Brost Suggested-by: Alistair Popple Signed-off-by: Mika Penttilä --- include/linux/migrate.h | 9 +- mm/hmm.c | 420 ++++++++++++++++++++++++++++++++++++++-- mm/migrate_device.c | 26 ++- 3 files changed, 438 insertions(+), 17 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 07429027960a..64d82bd16d3b 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -164,6 +164,7 @@ enum migrate_vma_info { MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, MIGRATE_VMA_SELECT_COMPOUND = 1 << 3, + MIGRATE_VMA_FAULT = 1 << 4, }; struct migrate_vma { @@ -201,10 +202,14 @@ struct migrate_vma { struct page *fault_page; }; -// TODO: enable migration static inline enum migrate_vma_info hmm_select_migrate(struct hmm_range *range) { - return 0; + enum migrate_vma_info minfo; + + minfo = (range->default_flags & HMM_PFN_REQ_MIGRATE) ? + range->migrate->flags : 0; + + return minfo; } int migrate_vma_setup(struct migrate_vma *args); diff --git a/mm/hmm.c b/mm/hmm.c index 642593c3505f..ce693938e5dc 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -476,34 +476,424 @@ static int hmm_vma_handle_absent_pmd(struct mm_walk *walk, unsigned long start, #endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */ #ifdef CONFIG_DEVICE_MIGRATION +/** + * migrate_vma_split_folio() - Helper function to split a THP folio + * @folio: the folio to split + * @fault_page: struct page associated with the fault if any + * + * Returns 0 on success + */ +static int migrate_vma_split_folio(struct folio *folio, + struct page *fault_page) +{ + int ret; + struct folio *fault_folio = fault_page ? page_folio(fault_page) : NULL; + struct folio *new_fault_folio = NULL; + + if (folio != fault_folio) { + folio_get(folio); + folio_lock(folio); + } + + ret = split_folio(folio); + if (ret) { + if (folio != fault_folio) { + folio_unlock(folio); + folio_put(folio); + } + return ret; + } + + new_fault_folio = fault_page ? page_folio(fault_page) : NULL; + + /* + * Ensure the lock is held on the correct + * folio after the split + */ + if (!new_fault_folio) { + folio_unlock(folio); + folio_put(folio); + } else if (folio != new_fault_folio) { + if (new_fault_folio != fault_folio) { + folio_get(new_fault_folio); + folio_lock(new_fault_folio); + } + folio_unlock(folio); + folio_put(folio); + } + + return 0; +} + static int hmm_vma_handle_migrate_prepare_pmd(const struct mm_walk *walk, pmd_t *pmdp, unsigned long start, unsigned long end, unsigned long *hmm_pfn) { - // TODO: implement migration entry insertion - return 0; + struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; + struct migrate_vma *migrate = range->migrate; + struct folio *fault_folio = NULL; + struct folio *folio; + enum migrate_vma_info minfo; + unsigned long i; + int r = 0; + + minfo = hmm_select_migrate(range); + if (!minfo) + return r; + + WARN_ON_ONCE(!migrate); + HMM_ASSERT_PMD_LOCKED(hmm_vma_walk, true); + + fault_folio = migrate->fault_page ? + page_folio(migrate->fault_page) : NULL; + + if (pmd_none(*pmdp)) + return hmm_pfns_fill(start, end, hmm_vma_walk, 0); + + if (!(hmm_pfn[0] & HMM_PFN_VALID)) + goto out; + + if (pmd_trans_huge(*pmdp)) { + if (!(minfo & MIGRATE_VMA_SELECT_SYSTEM)) + goto out; + + folio = pmd_folio(*pmdp); + if (is_huge_zero_folio(folio)) + return hmm_pfns_fill(start, end, hmm_vma_walk, 0); + + } else if (!pmd_present(*pmdp)) { + const softleaf_t entry = softleaf_from_pmd(*pmdp); + + folio = softleaf_to_folio(entry); + + if (!softleaf_is_device_private(entry)) + goto out; + + if (!(minfo & MIGRATE_VMA_SELECT_DEVICE_PRIVATE)) + goto out; + + if (folio->pgmap->owner != migrate->pgmap_owner) + goto out; + + } else { + hmm_vma_walk->last = start; + return -EBUSY; + } + + folio_get(folio); + + if (folio != fault_folio && unlikely(!folio_trylock(folio))) { + folio_put(folio); + hmm_pfns_fill(start, end, hmm_vma_walk, HMM_PFN_ERROR); + return 0; + } + + if (thp_migration_supported() && + (migrate->flags & MIGRATE_VMA_SELECT_COMPOUND) && + (IS_ALIGNED(start, HPAGE_PMD_SIZE) && + IS_ALIGNED(end, HPAGE_PMD_SIZE))) { + + struct page_vma_mapped_walk pvmw = { + .ptl = hmm_vma_walk->ptl, + .address = start, + .pmd = pmdp, + .vma = walk->vma, + }; + + hmm_pfn[0] |= HMM_PFN_MIGRATE | HMM_PFN_COMPOUND; + + r = set_pmd_migration_entry(&pvmw, folio_page(folio, 0)); + if (r) { + hmm_pfn[0] &= ~(HMM_PFN_MIGRATE | HMM_PFN_COMPOUND); + r = -ENOENT; // fallback + goto unlock_out; + } + for (i = 1, start += PAGE_SIZE; start < end; start += PAGE_SIZE, i++) + hmm_pfn[i] &= HMM_PFN_INOUT_FLAGS; + + } else { + r = -ENOENT; // fallback + goto unlock_out; + } + + +out: + return r; + +unlock_out: + if (folio != fault_folio) + folio_unlock(folio); + folio_put(folio); + goto out; } +/* + * Install migration entries if migration requested, either from fault + * or migrate paths. + * + */ static int hmm_vma_handle_migrate_prepare(const struct mm_walk *walk, pmd_t *pmdp, - pte_t *pte, + pte_t *ptep, unsigned long addr, - unsigned long *hmm_pfn) + unsigned long *hmm_pfn, + bool *unmapped) { - // TODO: implement migration entry insertion + struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; + struct migrate_vma *migrate = range->migrate; + struct mm_struct *mm = walk->vma->vm_mm; + struct folio *fault_folio = NULL; + enum migrate_vma_info minfo; + struct dev_pagemap *pgmap; + bool anon_exclusive; + struct folio *folio; + unsigned long pfn; + struct page *page; + softleaf_t entry; + pte_t pte, swp_pte; + bool writable = false; + + // Do we want to migrate at all? + minfo = hmm_select_migrate(range); + if (!minfo) + return 0; + + WARN_ON_ONCE(!migrate); + HMM_ASSERT_PTE_LOCKED(hmm_vma_walk, true); + + fault_folio = migrate->fault_page ? + page_folio(migrate->fault_page) : NULL; + + pte = ptep_get(ptep); + + if (pte_none(pte)) { + // migrate without faulting case + if (vma_is_anonymous(walk->vma)) { + *hmm_pfn &= HMM_PFN_INOUT_FLAGS; + *hmm_pfn |= HMM_PFN_MIGRATE; + goto out; + } + } + + if (!(hmm_pfn[0] & HMM_PFN_VALID)) + goto out; + + if (!pte_present(pte)) { + /* + * Only care about unaddressable device page special + * page table entry. Other special swap entries are not + * migratable, and we ignore regular swapped page. + */ + entry = softleaf_from_pte(pte); + if (!softleaf_is_device_private(entry)) + goto out; + + if (!(minfo & MIGRATE_VMA_SELECT_DEVICE_PRIVATE)) + goto out; + + page = softleaf_to_page(entry); + folio = page_folio(page); + if (folio->pgmap->owner != migrate->pgmap_owner) + goto out; + + if (folio_test_large(folio)) { + int ret; + + pte_unmap_unlock(ptep, hmm_vma_walk->ptl); + hmm_vma_walk->ptelocked = false; + ret = migrate_vma_split_folio(folio, + migrate->fault_page); + if (ret) + goto out_error; + return -EAGAIN; + } + + pfn = page_to_pfn(page); + if (softleaf_is_device_private_write(entry)) + writable = true; + } else { + pfn = pte_pfn(pte); + if (is_zero_pfn(pfn) && + (minfo & MIGRATE_VMA_SELECT_SYSTEM)) { + *hmm_pfn = HMM_PFN_MIGRATE; + goto out; + } + page = vm_normal_page(walk->vma, addr, pte); + if (page && !is_zone_device_page(page) && + !(minfo & MIGRATE_VMA_SELECT_SYSTEM)) { + goto out; + } else if (page && is_device_coherent_page(page)) { + pgmap = page_pgmap(page); + + if (!(minfo & + MIGRATE_VMA_SELECT_DEVICE_COHERENT) || + pgmap->owner != migrate->pgmap_owner) + goto out; + } + + folio = page ? page_folio(page) : NULL; + if (folio && folio_test_large(folio)) { + int ret; + + pte_unmap_unlock(ptep, hmm_vma_walk->ptl); + hmm_vma_walk->ptelocked = false; + + ret = migrate_vma_split_folio(folio, + migrate->fault_page); + if (ret) + goto out_error; + return -EAGAIN; + } + + writable = pte_write(pte); + } + + if (!page || !page->mapping) + goto out; + + /* + * By getting a reference on the folio we pin it and that blocks + * any kind of migration. Side effect is that it "freezes" the + * pte. + * + * We drop this reference after isolating the folio from the lru + * for non device folio (device folio are not on the lru and thus + * can't be dropped from it). + */ + folio = page_folio(page); + folio_get(folio); + + /* + * We rely on folio_trylock() to avoid deadlock between + * concurrent migrations where each is waiting on the others + * folio lock. If we can't immediately lock the folio we fail this + * migration as it is only best effort anyway. + * + * If we can lock the folio it's safe to set up a migration entry + * now. In the common case where the folio is mapped once in a + * single process setting up the migration entry now is an + * optimisation to avoid walking the rmap later with + * try_to_migrate(). + */ + + if (fault_folio == folio || folio_trylock(folio)) { + anon_exclusive = folio_test_anon(folio) && + PageAnonExclusive(page); + + flush_cache_page(walk->vma, addr, pfn); + + if (anon_exclusive) { + pte = ptep_clear_flush(walk->vma, addr, ptep); + + if (folio_try_share_anon_rmap_pte(folio, page)) { + set_pte_at(mm, addr, ptep, pte); + folio_unlock(folio); + folio_put(folio); + goto out; + } + } else { + pte = ptep_get_and_clear(mm, addr, ptep); + } + + if (pte_dirty(pte)) + folio_mark_dirty(folio); + + /* Setup special migration page table entry */ + if (writable) + entry = make_writable_migration_entry(pfn); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry(pfn); + else + entry = make_readable_migration_entry(pfn); + + if (pte_present(pte)) { + if (pte_young(pte)) + entry = make_migration_entry_young(entry); + if (pte_dirty(pte)) + entry = make_migration_entry_dirty(entry); + } + + swp_pte = swp_entry_to_pte(entry); + if (pte_present(pte)) { + if (pte_soft_dirty(pte)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pte)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + } else { + if (pte_swp_soft_dirty(pte)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_swp_uffd_wp(pte)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + } + + set_pte_at(mm, addr, ptep, swp_pte); + folio_remove_rmap_pte(folio, page, walk->vma); + folio_put(folio); + *hmm_pfn |= HMM_PFN_MIGRATE; + + if (pte_present(pte)) + *unmapped = true; + } else + folio_put(folio); +out: return 0; +out_error: + return -EFAULT; } static int hmm_vma_walk_split(pmd_t *pmdp, unsigned long addr, struct mm_walk *walk) { - // TODO : implement split - return 0; -} + struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; + struct migrate_vma *migrate = range->migrate; + struct folio *folio, *fault_folio; + spinlock_t *ptl; + int ret = 0; + HMM_ASSERT_UNLOCKED(hmm_vma_walk); + + fault_folio = (migrate && migrate->fault_page) ? + page_folio(migrate->fault_page) : NULL; + + ptl = pmd_lock(walk->mm, pmdp); + if (unlikely(!pmd_trans_huge(*pmdp))) { + spin_unlock(ptl); + goto out; + } + + folio = pmd_folio(*pmdp); + if (is_huge_zero_folio(folio)) { + spin_unlock(ptl); + split_huge_pmd(walk->vma, pmdp, addr); + } else { + folio_get(folio); + spin_unlock(ptl); + + if (folio != fault_folio) { + if (unlikely(!folio_trylock(folio))) { + folio_put(folio); + ret = -EBUSY; + goto out; + } + } else + folio_put(folio); + + ret = split_folio(folio); + if (fault_folio != folio) { + folio_unlock(folio); + folio_put(folio); + } + + } +out: + return ret; +} #else static int hmm_vma_handle_migrate_prepare_pmd(const struct mm_walk *walk, pmd_t *pmdp, @@ -518,7 +908,8 @@ static int hmm_vma_handle_migrate_prepare(const struct mm_walk *walk, pmd_t *pmdp, pte_t *pte, unsigned long addr, - unsigned long *hmm_pfn) + unsigned long *hmm_pfn, + bool *unmapped) { return 0; } @@ -573,6 +964,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, enum migrate_vma_info minfo; unsigned long addr = start; unsigned long *hmm_pfns; + bool unmapped = false; unsigned long i; pte_t *ptep; pmd_t pmd; @@ -654,7 +1046,7 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, goto again; } - r = hmm_vma_handle_pmd(walk, addr, end, hmm_pfns, pmd); + r = hmm_vma_handle_pmd(walk, start, end, hmm_pfns, pmd); // If not migrating we are done if (r || !minfo) { @@ -723,9 +1115,13 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, return r; } - r = hmm_vma_handle_migrate_prepare(walk, pmdp, ptep, addr, hmm_pfns); + r = hmm_vma_handle_migrate_prepare(walk, pmdp, ptep, addr, hmm_pfns, &unmapped); if (r == -EAGAIN) { HMM_ASSERT_UNLOCKED(hmm_vma_walk); + if (unmapped) { + flush_tlb_range(walk->vma, start, addr); + unmapped = false; + } goto again; } if (r) { @@ -733,6 +1129,8 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, break; } } + if (unmapped) + flush_tlb_range(walk->vma, start, addr); if (hmm_vma_walk->ptelocked) { pte_unmap_unlock(ptep - 1, hmm_vma_walk->ptl); diff --git a/mm/migrate_device.c b/mm/migrate_device.c index a4062fd21490..7ca5dc80d39b 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -734,7 +734,17 @@ static void migrate_vma_unmap(struct migrate_vma *migrate) */ int migrate_vma_setup(struct migrate_vma *args) { + int ret; long nr_pages = (args->end - args->start) >> PAGE_SHIFT; + struct hmm_range range = { + .notifier = NULL, + .start = args->start, + .end = args->end, + .hmm_pfns = args->src, + .dev_private_owner = args->pgmap_owner, + .migrate = args, + .default_flags = HMM_PFN_REQ_MIGRATE + }; args->start &= PAGE_MASK; args->end &= PAGE_MASK; @@ -759,17 +769,25 @@ int migrate_vma_setup(struct migrate_vma *args) args->cpages = 0; args->npages = 0; - migrate_vma_collect(args); + if (args->flags & MIGRATE_VMA_FAULT) + range.default_flags |= HMM_PFN_REQ_FAULT; + + ret = hmm_range_fault(&range); - if (args->cpages) - migrate_vma_unmap(args); + migrate_hmm_range_setup(&range); + + /* Remove migration PTEs */ + if (ret) { + migrate_vma_pages(args); + migrate_vma_finalize(args); + } /* * At this point pages are locked and unmapped, and thus they have * stable content and can safely be copied to destination memory that * is allocated by the drivers. */ - return 0; + return ret; } EXPORT_SYMBOL(migrate_vma_setup); -- 2.50.0