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Message-ID: <2baff2e5-b923-c39b-98e5-b3e7f77bd6d3@gmail.com>
Date: Thu, 15 Aug 2019 10:28:21 +0200
From: Christian König <ckoenig.leichtzumerken@...il.com>
To: Jason Gunthorpe <jgg@...pe.ca>, linux-mm@...ck.org
Cc: Andrea Arcangeli <aarcange@...hat.com>,
"David (ChunMing) Zhou" <David1.Zhou@....com>,
Ralph Campbell <rcampbell@...dia.com>,
Dimitri Sivanich <sivanich@....com>,
Gavin Shan <shangw@...ux.vnet.ibm.com>,
Andrea Righi <andrea@...terlinux.com>,
linux-rdma@...r.kernel.org, John Hubbard <jhubbard@...dia.com>,
"Kuehling, Felix" <Felix.Kuehling@....com>,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
Christian König <christian.koenig@....com>,
Jérôme Glisse <jglisse@...hat.com>,
iommu@...ts.linux-foundation.org, amd-gfx@...ts.freedesktop.org,
Jason Gunthorpe <jgg@...lanox.com>,
Alex Deucher <alexander.deucher@....com>,
intel-gfx@...ts.freedesktop.org, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v3 hmm 08/11] drm/radeon: use mmu_notifier_get/put for
struct radeon_mn
Am 07.08.19 um 01:15 schrieb Jason Gunthorpe:
> From: Jason Gunthorpe <jgg@...lanox.com>
>
> radeon is using a device global hash table to track what mmu_notifiers
> have been registered on struct mm. This is better served with the new
> get/put scheme instead.
>
> radeon has a bug where it was not blocking notifier release() until all
> the BO's had been invalidated. This could result in a use after free of
> pages the BOs. This is tied into a second bug where radeon left the
> notifiers running endlessly even once the interval tree became
> empty. This could result in a use after free with module unload.
>
> Both are fixed by changing the lifetime model, the BOs exist in the
> interval tree with their natural lifetimes independent of the mm_struct
> lifetime using the get/put scheme. The release runs synchronously and just
> does invalidate_start across the entire interval tree to create the
> required DMA fence.
>
> Additions to the interval tree after release are already impossible as
> only current->mm is used during the add.
>
> Signed-off-by: Jason Gunthorpe <jgg@...lanox.com>
Acked-by: Christian König <christian.koenig@....com>
But I'm wondering if we shouldn't completely drop radeon userptr support.
It's just to buggy,
Christian.
> ---
> drivers/gpu/drm/radeon/radeon.h | 3 -
> drivers/gpu/drm/radeon/radeon_device.c | 2 -
> drivers/gpu/drm/radeon/radeon_drv.c | 2 +
> drivers/gpu/drm/radeon/radeon_mn.c | 157 ++++++-------------------
> 4 files changed, 38 insertions(+), 126 deletions(-)
>
> AMD team: I wonder if kfd has similar lifetime issues?
>
> diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
> index 32808e50be12f8..918164f90b114a 100644
> --- a/drivers/gpu/drm/radeon/radeon.h
> +++ b/drivers/gpu/drm/radeon/radeon.h
> @@ -2451,9 +2451,6 @@ struct radeon_device {
> /* tracking pinned memory */
> u64 vram_pin_size;
> u64 gart_pin_size;
> -
> - struct mutex mn_lock;
> - DECLARE_HASHTABLE(mn_hash, 7);
> };
>
> bool radeon_is_px(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
> index dceb554e567446..788b1d8a80e660 100644
> --- a/drivers/gpu/drm/radeon/radeon_device.c
> +++ b/drivers/gpu/drm/radeon/radeon_device.c
> @@ -1325,8 +1325,6 @@ int radeon_device_init(struct radeon_device *rdev,
> init_rwsem(&rdev->pm.mclk_lock);
> init_rwsem(&rdev->exclusive_lock);
> init_waitqueue_head(&rdev->irq.vblank_queue);
> - mutex_init(&rdev->mn_lock);
> - hash_init(rdev->mn_hash);
> r = radeon_gem_init(rdev);
> if (r)
> return r;
> diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
> index a6cbe11f79c611..b6535ac91fdb74 100644
> --- a/drivers/gpu/drm/radeon/radeon_drv.c
> +++ b/drivers/gpu/drm/radeon/radeon_drv.c
> @@ -35,6 +35,7 @@
> #include <linux/module.h>
> #include <linux/pm_runtime.h>
> #include <linux/vga_switcheroo.h>
> +#include <linux/mmu_notifier.h>
>
> #include <drm/drm_crtc_helper.h>
> #include <drm/drm_drv.h>
> @@ -624,6 +625,7 @@ static void __exit radeon_exit(void)
> {
> pci_unregister_driver(pdriver);
> radeon_unregister_atpx_handler();
> + mmu_notifier_synchronize();
> }
>
> module_init(radeon_init);
> diff --git a/drivers/gpu/drm/radeon/radeon_mn.c b/drivers/gpu/drm/radeon/radeon_mn.c
> index 8c3871ed23a9f0..fc8254273a800b 100644
> --- a/drivers/gpu/drm/radeon/radeon_mn.c
> +++ b/drivers/gpu/drm/radeon/radeon_mn.c
> @@ -37,17 +37,8 @@
> #include "radeon.h"
>
> struct radeon_mn {
> - /* constant after initialisation */
> - struct radeon_device *rdev;
> - struct mm_struct *mm;
> struct mmu_notifier mn;
>
> - /* only used on destruction */
> - struct work_struct work;
> -
> - /* protected by rdev->mn_lock */
> - struct hlist_node node;
> -
> /* objects protected by lock */
> struct mutex lock;
> struct rb_root_cached objects;
> @@ -58,55 +49,6 @@ struct radeon_mn_node {
> struct list_head bos;
> };
>
> -/**
> - * radeon_mn_destroy - destroy the rmn
> - *
> - * @work: previously sheduled work item
> - *
> - * Lazy destroys the notifier from a work item
> - */
> -static void radeon_mn_destroy(struct work_struct *work)
> -{
> - struct radeon_mn *rmn = container_of(work, struct radeon_mn, work);
> - struct radeon_device *rdev = rmn->rdev;
> - struct radeon_mn_node *node, *next_node;
> - struct radeon_bo *bo, *next_bo;
> -
> - mutex_lock(&rdev->mn_lock);
> - mutex_lock(&rmn->lock);
> - hash_del(&rmn->node);
> - rbtree_postorder_for_each_entry_safe(node, next_node,
> - &rmn->objects.rb_root, it.rb) {
> -
> - interval_tree_remove(&node->it, &rmn->objects);
> - list_for_each_entry_safe(bo, next_bo, &node->bos, mn_list) {
> - bo->mn = NULL;
> - list_del_init(&bo->mn_list);
> - }
> - kfree(node);
> - }
> - mutex_unlock(&rmn->lock);
> - mutex_unlock(&rdev->mn_lock);
> - mmu_notifier_unregister(&rmn->mn, rmn->mm);
> - kfree(rmn);
> -}
> -
> -/**
> - * radeon_mn_release - callback to notify about mm destruction
> - *
> - * @mn: our notifier
> - * @mn: the mm this callback is about
> - *
> - * Shedule a work item to lazy destroy our notifier.
> - */
> -static void radeon_mn_release(struct mmu_notifier *mn,
> - struct mm_struct *mm)
> -{
> - struct radeon_mn *rmn = container_of(mn, struct radeon_mn, mn);
> - INIT_WORK(&rmn->work, radeon_mn_destroy);
> - schedule_work(&rmn->work);
> -}
> -
> /**
> * radeon_mn_invalidate_range_start - callback to notify about mm change
> *
> @@ -183,65 +125,44 @@ static int radeon_mn_invalidate_range_start(struct mmu_notifier *mn,
> return ret;
> }
>
> -static const struct mmu_notifier_ops radeon_mn_ops = {
> - .release = radeon_mn_release,
> - .invalidate_range_start = radeon_mn_invalidate_range_start,
> -};
> +static void radeon_mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
> +{
> + struct mmu_notifier_range range = {
> + .mm = mm,
> + .start = 0,
> + .end = ULONG_MAX,
> + .flags = 0,
> + .event = MMU_NOTIFY_UNMAP,
> + };
> +
> + radeon_mn_invalidate_range_start(mn, &range);
> +}
>
> -/**
> - * radeon_mn_get - create notifier context
> - *
> - * @rdev: radeon device pointer
> - *
> - * Creates a notifier context for current->mm.
> - */
> -static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev)
> +static struct mmu_notifier *radeon_mn_alloc_notifier(struct mm_struct *mm)
> {
> - struct mm_struct *mm = current->mm;
> struct radeon_mn *rmn;
> - int r;
> -
> - if (down_write_killable(&mm->mmap_sem))
> - return ERR_PTR(-EINTR);
> -
> - mutex_lock(&rdev->mn_lock);
> -
> - hash_for_each_possible(rdev->mn_hash, rmn, node, (unsigned long)mm)
> - if (rmn->mm == mm)
> - goto release_locks;
>
> rmn = kzalloc(sizeof(*rmn), GFP_KERNEL);
> - if (!rmn) {
> - rmn = ERR_PTR(-ENOMEM);
> - goto release_locks;
> - }
> + if (!rmn)
> + return ERR_PTR(-ENOMEM);
>
> - rmn->rdev = rdev;
> - rmn->mm = mm;
> - rmn->mn.ops = &radeon_mn_ops;
> mutex_init(&rmn->lock);
> rmn->objects = RB_ROOT_CACHED;
> -
> - r = __mmu_notifier_register(&rmn->mn, mm);
> - if (r)
> - goto free_rmn;
> -
> - hash_add(rdev->mn_hash, &rmn->node, (unsigned long)mm);
> -
> -release_locks:
> - mutex_unlock(&rdev->mn_lock);
> - up_write(&mm->mmap_sem);
> -
> - return rmn;
> -
> -free_rmn:
> - mutex_unlock(&rdev->mn_lock);
> - up_write(&mm->mmap_sem);
> - kfree(rmn);
> + return &rmn->mn;
> +}
>
> - return ERR_PTR(r);
> +static void radeon_mn_free_notifier(struct mmu_notifier *mn)
> +{
> + kfree(container_of(mn, struct radeon_mn, mn));
> }
>
> +static const struct mmu_notifier_ops radeon_mn_ops = {
> + .release = radeon_mn_release,
> + .invalidate_range_start = radeon_mn_invalidate_range_start,
> + .alloc_notifier = radeon_mn_alloc_notifier,
> + .free_notifier = radeon_mn_free_notifier,
> +};
> +
> /**
> * radeon_mn_register - register a BO for notifier updates
> *
> @@ -254,15 +175,16 @@ static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev)
> int radeon_mn_register(struct radeon_bo *bo, unsigned long addr)
> {
> unsigned long end = addr + radeon_bo_size(bo) - 1;
> - struct radeon_device *rdev = bo->rdev;
> + struct mmu_notifier *mn;
> struct radeon_mn *rmn;
> struct radeon_mn_node *node = NULL;
> struct list_head bos;
> struct interval_tree_node *it;
>
> - rmn = radeon_mn_get(rdev);
> - if (IS_ERR(rmn))
> - return PTR_ERR(rmn);
> + mn = mmu_notifier_get(&radeon_mn_ops, current->mm);
> + if (IS_ERR(mn))
> + return PTR_ERR(mn);
> + rmn = container_of(mn, struct radeon_mn, mn);
>
> INIT_LIST_HEAD(&bos);
>
> @@ -309,22 +231,13 @@ int radeon_mn_register(struct radeon_bo *bo, unsigned long addr)
> */
> void radeon_mn_unregister(struct radeon_bo *bo)
> {
> - struct radeon_device *rdev = bo->rdev;
> - struct radeon_mn *rmn;
> + struct radeon_mn *rmn = bo->mn;
> struct list_head *head;
>
> - mutex_lock(&rdev->mn_lock);
> - rmn = bo->mn;
> - if (rmn == NULL) {
> - mutex_unlock(&rdev->mn_lock);
> - return;
> - }
> -
> mutex_lock(&rmn->lock);
> /* save the next list entry for later */
> head = bo->mn_list.next;
>
> - bo->mn = NULL;
> list_del(&bo->mn_list);
>
> if (list_empty(head)) {
> @@ -335,5 +248,7 @@ void radeon_mn_unregister(struct radeon_bo *bo)
> }
>
> mutex_unlock(&rmn->lock);
> - mutex_unlock(&rdev->mn_lock);
> +
> + mmu_notifier_put(&rmn->mn);
> + bo->mn = NULL;
> }
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