>-----Original Message----- >From: dri-devel <dri-devel-boun...@lists.freedesktop.org> On Behalf Of >Ruhl, Michael J >Sent: Thursday, January 13, 2022 7:58 AM >To: guangming....@mediatek.com; sumit.sem...@linaro.org >Cc: jianjiao.z...@mediatek.com; lm...@codeaurora.org; >wsd_upstr...@mediatek.com; christian.koe...@amd.com; linux- >ker...@vger.kernel.org; dri-devel@lists.freedesktop.org; >yf.w...@mediatek.com; linaro-mm-...@lists.linaro.org; linux- >media...@lists.infradead.org; libo.k...@mediatek.com; >benjamin.gaign...@linaro.org; bo.s...@mediatek.com; >matthias....@gmail.com; labb...@redhat.com; >mingyuan...@mediatek.com; linux-arm-ker...@lists.infradead.org; linux- >me...@vger.kernel.org >Subject: RE: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation > > >>-----Original Message----- >>From: dri-devel <dri-devel-boun...@lists.freedesktop.org> On Behalf Of >>guangming....@mediatek.com >>Sent: Thursday, January 13, 2022 7:34 AM >>To: sumit.sem...@linaro.org >>Cc: linux-arm-ker...@lists.infradead.org; mingyuan...@mediatek.com; >>Guangming <guangming....@mediatek.com>; >>wsd_upstr...@mediatek.com; linux-ker...@vger.kernel.org; dri- >>de...@lists.freedesktop.org; linaro-mm-...@lists.linaro.org; >>yf.w...@mediatek.com; libo.k...@mediatek.com; >>benjamin.gaign...@linaro.org; bo.s...@mediatek.com; >>matthias....@gmail.com; linux-media...@lists.infradead.org; >>lm...@codeaurora.org; labb...@redhat.com; christian.koe...@amd.com; >>jianjiao.z...@mediatek.com; linux-me...@vger.kernel.org >>Subject: [PATCH v3] dma-buf: dma-heap: Add a size check for allocation >> >>From: Guangming <guangming....@mediatek.com> >> >>Add a size check for allocation since the allocation size is >>always less than the total DRAM size. >> >>Without this check, once the invalid size allocation runs on a process that >>can't be killed by OOM flow(such as "gralloc" on Android devices), it will >>cause a kernel exception, and to make matters worse, we can't find who are >>using >>so many memory with "dma_buf_debug_show" since the relevant dma-buf >>hasn't exported. >> >>To make OOM issue easier, maybe need dma-buf framework to dump the >>buffer size >>under allocating in "dma_buf_debug_show". >> >>Signed-off-by: Guangming <guangming....@mediatek.com> >>Signed-off-by: jianjiao zeng <jianjiao.z...@mediatek.com> >>--- >>v3: 1. update patch, use right shift to replace division. >> 2. update patch, add reason in code and commit message. >>v2: 1. update size limitation as total_dram page size. >> 2. update commit message >>--- >> drivers/dma-buf/dma-heap.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >>diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c >>index 56bf5ad01ad5..1fd382712584 100644 >>--- a/drivers/dma-buf/dma-heap.c >>+++ b/drivers/dma-buf/dma-heap.c >>@@ -55,6 +55,16 @@ static int dma_heap_buffer_alloc(struct dma_heap >>*heap, size_t len, >> struct dma_buf *dmabuf; >> int fd; >> >>+ /* >>+ * Invalid size check. The "len" should be less than totalram. >>+ * >>+ * Without this check, once the invalid size allocation runs on a >>process >>that >>+ * can't be killed by OOM flow(such as "gralloc" on Android devices), it >>will >>+ * cause a kernel exception, and to make matters worse, we can't find >>who are using >>+ * so many memory with "dma_buf_debug_show" since the relevant >>dma-buf hasn't exported. >>+ */ >>+ if (len >> PAGE_SHIFT > totalram_pages()) > >If your "heap" is from cma, is this still a valid check?
And thinking a bit further, if I create a heap from something else (say device memory), you will need to be able to figure out the maximum allowable check for the specific heap. Maybe the heap needs a callback for max size? m >M > >>+ return -EINVAL; >> /* >> * Allocations from all heaps have to begin >> * and end on page boundaries. >>-- >>2.17.1
