From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793307061; b=KX7zqEsMBhwOZE37F/LKHuvkevYgq2mo77sHQO/kOBK6q+M33sqf8wKuuihFVyCVmSiU 5SMwI0Xp8I0dKY5SgbaAw9gY5KSZQaGfTw5YtnvDycpmlQ4TpwtGeJhMRbyKU+dSnNQnO 5yMY84Xvmuy7ysGdGxSZ7vvVMzRWV6JbxKnowMlrOw/j4+EU5lLixCK2wlOESp0zDEch+ +wEw6rhU8C5IfHYXAxDMTEmMZ19BUY97uDqRJqK3Tn0jhg9y1UsRQXO+z6XH4M3xFSftx NmCvFDgqqtEtDxUFUPok+KNuEJWlvrONG9ckpohWiYIrJeAUT4hmW4KUI7nTiPlsHJw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793307061; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=OmrddnalYvKzrQnN9N4Fpu9NVAES2TsOMe4SsI3z9gU=; b=V+W5SXee/wznbgY93xY44lZulWKC4GGkLBDBOT9DPbyKuK9BsHyug5AQFuZO3WtvMJjj P6d+2oScW72YqfTNKtX4WY5STKSlZwE8RAJFEhXHykZ4iHrmcavJVw7o/5PxDAlm8dElY 2y9xyqoN/YfKkMviV7KChM7UVc6RwFpQ/nM9oYSLIi/9IaiLX622d4bBDR3SAnA4a7aGE vt2awu5jyvkPMMisH0H4DWMjxXVYLaZsOSF4VuoJlB6kXtgeWhBUTSpk6oPudHkYDG6wb kuw1lvDsVVXcbckhbDcUxip/F5tKvnDHJXuPNFFG/Ek5abwdbeWL94ehx59CgxdRBDw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="GauLCy/1"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 529C260A2601; Thu, 29 Oct 2026 20:51:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=GauLCy/1 Received: by smtp.kernel.org (Postfix) with ESMTPSA id B00911F01825; Thu, 29 Oct 2026 20:44:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306675; bh=OmrddnalYvKzrQnN9N4Fpu9NVAES2TsOMe4SsI3z9gU=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=GauLCy/1HrYbdieZoYJGY/PpIUS1vgONUu0M4PlXJvY7eY+GegQj06Bc3k52Nn7Cw 5pUOiZmQPSa/agrZVJmrfiWcTl/MEWxkZ9UQsk7lluRie9slFArS3/SevT9Xccdva3 jp2ZFiK7k5Rm5+WgEwWwD32w960RLwKV1pQDqkERuQqbjtkTQtpbzWr7jdja43hl2C c8k7J5I4N2CU6YXX6Fvp4i5opY3LoX3l2OPr87naVfONU+oHtwZSXt5gIoOIzHgVXo jtFFykZR1o4q1kxv0399ek+IcViDhuU9YWAlcP+xsYEpMNrWrwGCMJzm0kwU8GDd9N c2NA3KmLJdFDw== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:40 +0100 Subject: [PATCH v2 45/47] mm/cma: don't release CMA pages still in use X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261029-fixes_core-v2-45-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2252; i=david@kernel.org; h=from:subject:message-id; bh=3kpfFp5NOxLKJV7MN0qgqEyHjOOrTqFsf7HE3Qur7Ks=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer+16LPZT4EOJ2H3DwG0neWorjk3wfGRVsoy7nXl93 YOjzLF9HaUsDGIcDLJiiixBwfcNXr5cV1vtxscMM4eVCWQIAxenAEzk7zaG/wGvIi2+nrw7edI2 i513/4c0ZS6asqr28e2KUp2fNmp7rUMZfrPoSJ2ovysSvbya44cCH9+H3rqFRjUPV/WUWk7Yv/V nMCsA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A From: Rik van Riel When a driver calls dma_free_contiguous() before quiescing DMA, the page might still have a reference from the device. put_page_testzero() there returns false, WARN fires, but the code proceeds to free_contig_frozen_range() putting a live page onto buddy and clearing the bitmap. A subsequent allocation can hand the same PFN to a new owner while the original holder still references it. A concurrent put_page() that drops the last reference between the testzero loop and free_contig_frozen_range() can double-queue the page via page->lru, corrupting buddy lists. Avoid the corruption by not freeing a CMA region if any of the pages inside are still in use. Make it explicit in the warning that the driver allowed a leak. While at it, use page_ref_freeze() to make the semantics clearer and switch to pr_warn_ratelimited(). Fixes: 9bda131c6093 ("mm: cma: add cma_alloc_frozen{_compound}()") Cc: stable@vger.kernel.org Signed-off-by: Rik van Riel Link: https://patch.msgid.link/20260811132045.5f114772@fangorn [ david: use page_ref_freeze() + pr_warn_ratelimited() ] Acked-by: Lorenzo Stoakes (ARM) Acked-by: Muchun Song Signed-off-by: David Hildenbrand (Arm) --- mm/cma.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/cma.c b/mm/cma.c index a10ea37a261d..871f95c9ae9f 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -1020,7 +1020,7 @@ bool cma_release(struct cma *cma, const struct page *pages, unsigned long count) { struct cma_memrange *cmr; - unsigned long ret = 0; + unsigned long leaked = 0; unsigned long i, pfn; cmr = find_cma_memrange(cma, pages, count); @@ -1029,9 +1029,13 @@ bool cma_release(struct cma *cma, const struct page *pages, pfn = page_to_pfn(pages); for (i = 0; i < count; i++, pfn++) - ret += !put_page_testzero(pfn_to_page(pfn)); + leaked += !page_ref_freeze(pfn_to_page(pfn), 1); - WARN(ret, "%lu pages are still in use!\n", ret); + if (leaked) { + pr_warn_ratelimited("%lu pages are still in use, not freeing CMA region!\n", + leaked); + return true; + } __cma_release_frozen(cma, cmr, pages, count); -- 2.43.0