From 08d9a4580f71120be3c5b221af32dca00a48ceb0 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 20 Feb 2026 14:19:59 +0530 Subject: tee: shm: Remove refcounting of kernel pages MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Earlier TEE subsystem assumed to refcount all the memory pages to be shared with TEE implementation to be refcounted. However, the slab allocations within the kernel don't allow refcounting kernel pages. It is rather better to trust the kernel clients to not free pages while being shared with TEE implementation. Hence, remove refcounting of kernel pages from register_shm_helper() API. Fixes: b9c0e49abfca ("mm: decline to manipulate the refcount on a slab page") Reported-by: Marco Felsch Reported-by: Sven Püschel Signed-off-by: Matthew Wilcox Co-developed-by: Sumit Garg Signed-off-by: Sumit Garg Tested-by: Sven Püschel Signed-off-by: Jens Wiklander --- drivers/tee/tee_shm.c | 27 --------------------------- 1 file changed, 27 deletions(-) diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index 6c5b9e352e5e..e9ea9f80cfd9 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -23,29 +23,11 @@ struct tee_shm_dma_mem { struct page *page; }; -static void shm_put_kernel_pages(struct page **pages, size_t page_count) -{ - size_t n; - - for (n = 0; n < page_count; n++) - put_page(pages[n]); -} - -static void shm_get_kernel_pages(struct page **pages, size_t page_count) -{ - size_t n; - - for (n = 0; n < page_count; n++) - get_page(pages[n]); -} - static void release_registered_pages(struct tee_shm *shm) { if (shm->pages) { if (shm->flags & TEE_SHM_USER_MAPPED) unpin_user_pages(shm->pages, shm->num_pages); - else - shm_put_kernel_pages(shm->pages, shm->num_pages); kfree(shm->pages); } @@ -477,13 +459,6 @@ register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, goto err_put_shm_pages; } - /* - * iov_iter_extract_kvec_pages does not get reference on the pages, - * get a reference on them. - */ - if (iov_iter_is_kvec(iter)) - shm_get_kernel_pages(shm->pages, num_pages); - shm->offset = off; shm->size = len; shm->num_pages = num_pages; @@ -499,8 +474,6 @@ register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, err_put_shm_pages: if (!iov_iter_is_kvec(iter)) unpin_user_pages(shm->pages, shm->num_pages); - else - shm_put_kernel_pages(shm->pages, shm->num_pages); err_free_shm_pages: kfree(shm->pages); err_free_shm: -- cgit v1.2.3