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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9A2D1C98318 for ; Thu, 24 Sep 2026 06:53:50 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D10FC10F32D; Thu, 24 Sep 2026 06:53:48 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.b="JtNrIyvP"; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1151910F329 for ; Thu, 24 Sep 2026 06:53:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1790232827; 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=Kki3z56ATUJrZFB3MBKMIKwGUeQgKMm6Uy7jrjVIGAU=; b=JtNrIyvPjxhvZMlzu9nISxidEck/rgAXJxZRvppD+yQ6FReZGinWwFulZb+ZiSqovARzzP thtKQIY6PNrcUQhTjGatASJt9Zg6kLGskeJV0JoNRKhPFK8nPZjl6Ew42dqCMDMYlJOPsY 3J6CPDHkvrSez7+c6XqZgAVS0YeYtxk= 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-473-hNv83vmnOXGQLZMph_jCGA-1; Thu, 24 Sep 2026 02:53:40 -0400 X-MC-Unique: hNv83vmnOXGQLZMph_jCGA-1 X-Mimecast-MFC-AGG-ID: hNv83vmnOXGQLZMph_jCGA_1790232819 Received: by mail-lj1-f197.google.com with SMTP id 38308e7fff4ca-3a468782b61so7062231fa.0 for ; Wed, 23 Sep 2026 23:53:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790232819; x=1790837619; h=content-transfer-encoding:content-type: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 :content-type; bh=Kki3z56ATUJrZFB3MBKMIKwGUeQgKMm6Uy7jrjVIGAU=; b=GrdMs3H9jK6hzd+fEDhE5s22jf9YRu1O7TOgd9l6gH7vqcDuLzhMhgSrewFIlbifO6 q4DRhXulBKgk2p42D9yWX0oZzDlPDkqFrh/EG8Rnu6V0UrcMmozEiVAR+Ow5F/DKIqbc 0m2/5xuel+CL6CWx0Z9a6fgzXcQ2GQiRExa5gStsJatjWPL2IZie0T127r8OUc17fDxF iNwXzpPZ/JArc9vUsgBcbA6HuwoXdV2/v1ltFX0gk7dLUgtL6JLQ4h5YwYKRDuxqPnLm ySu9J0GSi8QzEWAn0MeMOUI+xJTsl7+4YnxraXxFbZ9Bo65emvICZeXp1PnEzsMjEPQG hgRA== X-Gm-Message-State: AFuF++nYkrqaA3TOv3gAfKA6cHZTHAvev2BJeYIY6IJfYN0DDwYCrVRs beZgYaTyk/B3xsw2ubvrHEE1o+d8Nk5ivPpFWyW2M3yC7p11DEe3RwZvxXw+EmMuNEuKS0wQgMQ TbnkGBicfXr6fTnHudZWMV4hpSJ5Y1TnICdQmX2WMFOlCdKOnXtpihpKlufIeS7tPYZav X-Gm-Gg: AYBFou2E8V+mZz5LhVmmVFrogBgjzLSWT5RhwTHE0auzRLAvlmq0JK2I7hPm6BBwgHS Mxm8ZndpZcnYvSRwjJvP98SgFKloQDuLh/YEqoCYVn0NteOLKgx0nszKQ2etQZp3O/383BFO+H5 A1Fl7eHKzJAYJpz9htIdYOQIcCkeTsmqltZAvhSCQRrCKDambBpeC5R0uzRGGhjEwyDUV6loWhr GUMc5C793Sly3fGrnxBVg7dQTVWf9P0tP3zw0i8LKEqpTrTSvFO4MxZmNb0B8hQ/1KcUK/DkSG5 NrVn22YP5pTTgq/rZKOMxAp1W877hnCZGqm8E4DtdhvZF239JKqW0hO6dx2Ptt7PT+ohIqProvS 2jG0JnSigEaC6w/6fIkGinfm9MWwig+M= X-Received: by 2002:a05:651c:b0a:b0:3a3:749e:319b with SMTP id 38308e7fff4ca-3a63de182e4mr2715051fa.15.1790232819294; Wed, 23 Sep 2026 23:53:39 -0700 (PDT) X-Received: by 2002:a05:651c:b0a:b0:3a3:749e:319b with SMTP id 38308e7fff4ca-3a63de182e4mr2714961fa.15.1790232818795; Wed, 23 Sep 2026 23:53:38 -0700 (PDT) Received: from fedora (89-27-86-246.bb.dnainternet.fi. [89.27.86.246]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-3a63bf57909sm4803141fa.29.2026.09.23.23.53.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 23:53:36 -0700 (PDT) From: mpenttil@redhat.com To: linux-mm@kvack.org Cc: dri-devel@lists.freedesktop.org, intel-xe@lists.freedesktop.org, 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 , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Subject: [PATCH v15 03/11] mm/hmm: preparations for HMM to participate in migration Date: Thu, 24 Sep 2026 09:53:05 +0300 Message-ID: <20260924065313.899730-4-mpenttil@redhat.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260924065313.899730-1-mpenttil@redhat.com> References: <20260924065313.899730-1-mpenttil@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 4od_1n_qVQN-iIk41uIKXU8cC17FmlGBEd60VUVqPTM_1790232819 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Mika Penttilä For migration to happen after hmm_range_fault(), the vma has to retrieved. Luckily, pagewalk already resolves that for us, so just have to save it for further use. For migration, mmap_lock has to be hold for the whole operation, so vma stays stable. In case lock-drop behavior is requested, return an error while migrating. Also, rename some struct hmm_vma_walk fields to solve namespace collisions, and we are later introducing more xxlocked fields so be unambiguous. Take care also of firing the mmu_notifier when migrating. Also, prepare for differencies of how mm_struct * is retrieved in fault and migrate_vma paths. 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 | 49 +++++++++++++++++- lib/test_hmm.c | 2 +- mm/hmm.c | 110 ++++++++++++++++++++++++++++++++++------ 3 files changed, 144 insertions(+), 17 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 280ec9a866c7..01c5f62a56e9 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -5,6 +5,7 @@ #include #include #include +#include #include #include @@ -108,6 +109,29 @@ static inline void softleaf_entry_wait_on_locked(softleaf_t entry, spinlock_t *p spin_unlock(ptl); } +enum migrate_vma_info { + MIGRATE_VMA_SELECT_NONE = 0, + MIGRATE_VMA_SELECT_COMPOUND = MIGRATE_VMA_SELECT_NONE, +}; + +static inline enum migrate_vma_info hmm_select_migrate(struct hmm_range *range) +{ + return MIGRATE_VMA_SELECT_NONE; +} + +static inline void hmm_fill_migrate_vma(struct hmm_range *range, + struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ +} + +#ifdef CONFIG_MMU_NOTIFIER +static inline struct mm_struct *hmm_range_fault_mm(struct hmm_range *range) +{ + return range->notifier->mm; +} +#endif #endif /* CONFIG_MIGRATION */ #ifdef CONFIG_NUMA_BALANCING @@ -151,7 +175,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn) return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; } -enum migrate_vma_direction { +enum migrate_vma_info { MIGRATE_VMA_SELECT_SYSTEM = 1 << 0, MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1, MIGRATE_VMA_SELECT_DEVICE_COHERENT = 1 << 2, @@ -193,6 +217,29 @@ 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; +} + +#ifdef CONFIG_MMU_NOTIFIER +static inline struct mm_struct *hmm_range_fault_mm(struct hmm_range *range) +{ + return range->notifier ? range->notifier->mm : range->migrate->vma->vm_mm; +} +#endif + +static inline void hmm_fill_migrate_vma(struct hmm_range *range, + struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ + range->migrate->vma = vma; + range->migrate->start = start; + range->migrate->end = end; +} + int migrate_vma_setup(struct migrate_vma *args); void migrate_vma_pages(struct migrate_vma *migrate); void migrate_vma_finalize(struct migrate_vma *migrate); diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 6911daa9f854..cd88e8177d0a 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -145,7 +145,7 @@ static bool dmirror_is_private_zone(struct dmirror_device *mdevice) HMM_DMIRROR_MEMORY_DEVICE_PRIVATE); } -static enum migrate_vma_direction +static enum migrate_vma_info dmirror_select_device(struct dmirror *dmirror) { return (dmirror->mdevice->zone_device_type == diff --git a/mm/hmm.c b/mm/hmm.c index 2f1e98c6b644..4e9542aedc25 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -28,15 +29,23 @@ #include #include #include +#include #include "internal.h" struct hmm_vma_walk { - struct hmm_range *range; - bool *locked; - unsigned long last; - unsigned long end; - unsigned int required_fault; + struct mmu_notifier_range mmu_range; + /* Set once mmu_range is armed with mmu_notifier_invalidate_range_start() */ + bool mmu_armed; + struct vm_area_struct *vma; + struct hmm_range *range; + unsigned long start; + unsigned long end; + unsigned long last; + /* fault and lock drop related fields */ + bool *mmlocked; + unsigned long fault_end; + unsigned int required_fault; }; /* @@ -95,7 +104,7 @@ static int hmm_record_fault(unsigned long addr, unsigned long end, WARN_ON_ONCE(!required_fault); hmm_vma_walk->last = addr; - hmm_vma_walk->end = end; + hmm_vma_walk->fault_end = end; hmm_vma_walk->required_fault = required_fault; return HMM_FAULT_PENDING; } @@ -400,6 +409,58 @@ static int hmm_vma_handle_absent_pmd(struct mm_walk *walk, unsigned long start, } #endif /* CONFIG_ARCH_HAS_PMD_SOFTLEAVES */ +static int hmm_vma_capture_migrate_range(unsigned long start, + unsigned long end, + struct mm_walk *walk) +{ + struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; + + if (!hmm_select_migrate(range)) + return 0; + + if (hmm_vma_walk->vma && (hmm_vma_walk->vma != walk->vma)) + return -ERANGE; + + hmm_vma_walk->vma = walk->vma; + + if (end - start > range->end - range->start) + return -ERANGE; + + if (!hmm_vma_walk->mmu_armed) { + hmm_vma_walk->start = start; + hmm_vma_walk->end = end; + mmu_notifier_range_init_owner(&hmm_vma_walk->mmu_range, MMU_NOTIFY_MIGRATE, 0, + walk->vma->vm_mm, start, end, + range->dev_private_owner); + mmu_notifier_invalidate_range_start(&hmm_vma_walk->mmu_range); + hmm_vma_walk->mmu_armed = true; + } + + return 0; +} + +static void hmm_vma_post_range_fault(struct hmm_vma_walk *hmm_vma_walk) +{ + + struct hmm_range *range = hmm_vma_walk->range; + + if (hmm_select_migrate(range) && + hmm_vma_walk->mmu_armed) { + /* + * The migrate_vma path has the following initialized, + * so take care of fault path below. + */ + if (range->notifier) { + hmm_fill_migrate_vma(range, + hmm_vma_walk->vma, + hmm_vma_walk->start, + hmm_vma_walk->end); + } + mmu_notifier_invalidate_range_end(&hmm_vma_walk->mmu_range); + } +} + static int hmm_vma_walk_pmd(pmd_t *pmdp, unsigned long start, unsigned long end, @@ -594,6 +655,11 @@ static int hmm_vma_walk_test(unsigned long start, unsigned long end, struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; struct vm_area_struct *vma = walk->vma; + int r; + + r = hmm_vma_capture_migrate_range(start, end, walk); + if (r) + return r; if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)) && vma->vm_flags & VM_READ) @@ -646,12 +712,12 @@ static int hmm_do_fault(struct mm_struct *mm, struct hmm_vma_walk *hmm_vma_walk) { unsigned long addr = hmm_vma_walk->last; - unsigned long end = hmm_vma_walk->end; + unsigned long end = hmm_vma_walk->fault_end; unsigned int required_fault = hmm_vma_walk->required_fault; unsigned int fault_flags = FAULT_FLAG_REMOTE; struct vm_area_struct *vma; - if (hmm_vma_walk->locked) + if (hmm_vma_walk->mmlocked) fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; vma = vma_lookup(mm, addr); @@ -670,8 +736,8 @@ static int hmm_do_fault(struct mm_struct *mm, ret = handle_mm_fault(vma, addr, fault_flags, NULL); if (ret & (VM_FAULT_COMPLETED | VM_FAULT_RETRY)) { - if (hmm_vma_walk->locked) /* needed by sparse */ - *hmm_vma_walk->locked = false; + if (hmm_vma_walk->mmlocked) /* needed by sparse */ + *hmm_vma_walk->mmlocked = false; else WARN_ON_ONCE(1); /* broken fault handler */ return HMM_FAULT_UNLOCKED; @@ -694,19 +760,31 @@ static int hmm_range_fault_locked(struct hmm_range *range, bool *locked) { struct hmm_vma_walk hmm_vma_walk = { .range = range, - .locked = locked, + .mmlocked = locked, .last = range->start, }; - struct mm_struct *mm = range->notifier->mm; + /* + * Could be serving a device fault or come from migrate + * entry point. For the former we have not resolved the vma + * yet, and the latter we don't have a notifier (but have a vma). + * + */ + struct mm_struct *mm = hmm_range_fault_mm(range); int ret; + /* Migration is incompatible with mmap lock drop */ + if (locked && hmm_select_migrate(range)) + return -EINVAL; + mmap_assert_locked(mm); do { /* If range is no longer valid force retry. */ - if (mmu_interval_check_retry(range->notifier, - range->notifier_seq)) - return -EBUSY; + if (range->notifier && mmu_interval_check_retry(range->notifier, + range->notifier_seq)) { + ret = -EBUSY; + break; + } ret = walk_page_range(mm, hmm_vma_walk.last, range->end, &hmm_walk_ops, &hmm_vma_walk); /* @@ -732,6 +810,8 @@ static int hmm_range_fault_locked(struct hmm_range *range, bool *locked) * output, and all >= are still at their input values. */ } while (ret == -EBUSY); + + hmm_vma_post_range_fault(&hmm_vma_walk); return ret; } -- 2.55.0