Hi, This is regarding dma memory usage in my kernel driver on arm64 processor. I have a structure in my kernel driver as shown below- struct dummy_dc_dmabuf { struct dma_buf *buf; struct dma_buf_attachment *attach; struct sg_table *sgt; }; For this I am able to get memory allocated like below void pin_window(struct dummy_dmabuf **dum_buf, int fd, struct device *dev) { struct dummy_dmabuf *dum_dmabuf; dma_addr_t dma_addr; dum_dmabuf = kzalloc(sizeof(*dum_dmabuf), GFP_KERNEL); if (!dum_dmabuf) return -ENOMEM; dum_dmabuf->buf = dma_buf_get(fd); dum_dmabuf->attach = dma_buf_attach(dum_dmabuf->buf, dev->parent); dum_dmabuf->sgt = dma_buf_map_attachment(dum_dmabuf->attach, DMA_TO_DEVICE); *dum_buf = dum_dmabuf; } As per ldd3 , Chapter 15 - "The DMA controller is a shared resource, and confusion could arise if more than one processor attempts to program it simultaneously. For that reason, the controller is protected by a spinlock, called dma_spin_lock. Drivers should not manipulate the lock directly;" However, I am using this in kthreads and I want to protect it without using mutex/spilock. Apart from protecting it with spinlock or mutex, is their anyway to mark this dma buffer as read-only so that other threads(after concerned thread has accessed it) cannot access the dma buffer. Regards, Saket Sinha