From: Philip Yang Philip.Yang@amd.com
[ Upstream commit 367c9b0f1b8750a704070e7ae85234d591290434 ]
svm_deferred_list work should continue to handle deferred_range_list which maybe split to child range to avoid child range leak, and remove ranges mmu interval notifier to avoid mm mm_count leak. So taking mm reference when adding range to deferred list, to ensure mm is valid in the scheduled deferred_list_work, and drop the mm referrence after range is handled.
Signed-off-by: Philip Yang Philip.Yang@amd.com Reported-by: Ruili Ji ruili.ji@amd.com Reviewed-by: Felix Kuehling Felix.Kuehling@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 62 ++++++++++++++++------------ 1 file changed, 36 insertions(+), 26 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c index f2805ba74c80..225affcddbc1 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c @@ -1985,10 +1985,9 @@ svm_range_update_notifier_and_interval_tree(struct mm_struct *mm, }
static void -svm_range_handle_list_op(struct svm_range_list *svms, struct svm_range *prange) +svm_range_handle_list_op(struct svm_range_list *svms, struct svm_range *prange, + struct mm_struct *mm) { - struct mm_struct *mm = prange->work_item.mm; - switch (prange->work_item.op) { case SVM_OP_NULL: pr_debug("NULL OP 0x%p prange 0x%p [0x%lx 0x%lx]\n", @@ -2071,34 +2070,41 @@ static void svm_range_deferred_list_work(struct work_struct *work) pr_debug("enter svms 0x%p\n", svms);
p = container_of(svms, struct kfd_process, svms); - /* Avoid mm is gone when inserting mmu notifier */ - mm = get_task_mm(p->lead_thread); - if (!mm) { - pr_debug("svms 0x%p process mm gone\n", svms); - return; - } -retry: - mmap_write_lock(mm); - - /* Checking for the need to drain retry faults must be inside - * mmap write lock to serialize with munmap notifiers. - */ - if (unlikely(atomic_read(&svms->drain_pagefaults))) { - mmap_write_unlock(mm); - svm_range_drain_retry_fault(svms); - goto retry; - }
spin_lock(&svms->deferred_list_lock); while (!list_empty(&svms->deferred_range_list)) { prange = list_first_entry(&svms->deferred_range_list, struct svm_range, deferred_list); - list_del_init(&prange->deferred_list); spin_unlock(&svms->deferred_list_lock);
pr_debug("prange 0x%p [0x%lx 0x%lx] op %d\n", prange, prange->start, prange->last, prange->work_item.op);
+ mm = prange->work_item.mm; +retry: + mmap_write_lock(mm); + + /* Checking for the need to drain retry faults must be inside + * mmap write lock to serialize with munmap notifiers. + */ + if (unlikely(atomic_read(&svms->drain_pagefaults))) { + mmap_write_unlock(mm); + svm_range_drain_retry_fault(svms); + goto retry; + } + + /* Remove from deferred_list must be inside mmap write lock, for + * two race cases: + * 1. unmap_from_cpu may change work_item.op and add the range + * to deferred_list again, cause use after free bug. + * 2. svm_range_list_lock_and_flush_work may hold mmap write + * lock and continue because deferred_list is empty, but + * deferred_list work is actually waiting for mmap lock. + */ + spin_lock(&svms->deferred_list_lock); + list_del_init(&prange->deferred_list); + spin_unlock(&svms->deferred_list_lock); + mutex_lock(&svms->lock); mutex_lock(&prange->migrate_mutex); while (!list_empty(&prange->child_list)) { @@ -2109,19 +2115,20 @@ static void svm_range_deferred_list_work(struct work_struct *work) pr_debug("child prange 0x%p op %d\n", pchild, pchild->work_item.op); list_del_init(&pchild->child_list); - svm_range_handle_list_op(svms, pchild); + svm_range_handle_list_op(svms, pchild, mm); } mutex_unlock(&prange->migrate_mutex);
- svm_range_handle_list_op(svms, prange); + svm_range_handle_list_op(svms, prange, mm); mutex_unlock(&svms->lock); + mmap_write_unlock(mm); + + /* Pairs with mmget in svm_range_add_list_work */ + mmput(mm);
spin_lock(&svms->deferred_list_lock); } spin_unlock(&svms->deferred_list_lock); - - mmap_write_unlock(mm); - mmput(mm); pr_debug("exit svms 0x%p\n", svms); }
@@ -2139,6 +2146,9 @@ svm_range_add_list_work(struct svm_range_list *svms, struct svm_range *prange, prange->work_item.op = op; } else { prange->work_item.op = op; + + /* Pairs with mmput in deferred_list_work */ + mmget(mm); prange->work_item.mm = mm; list_add_tail(&prange->deferred_list, &prange->svms->deferred_range_list);