Hello Christian König,
The patch 648bc3574716: "drm/ttm: add transparent huge page support
for DMA allocations v2" from Jul 6, 2017, leads to the following
static checker warning:
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c:314 __ttm_dma_alloc_page()
error: 'vaddr' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
295 static struct dma_page *__ttm_dma_alloc_page(struct dma_pool *pool)
296 {
297 struct dma_page *d_page;
298 unsigned long attrs = 0;
299 void *vaddr;
300
301 d_page = kmalloc(sizeof(struct dma_page), GFP_KERNEL);
302 if (!d_page)
303 return NULL;
304
305 if (pool->type & IS_HUGE)
306 attrs = DMA_ATTR_NO_WARN;
307
308 vaddr = dma_alloc_attrs(pool->dev, pool->size, &d_page->dma,
309 pool->gfp_flags, attrs);
310 if (vaddr) {
311 if (is_vmalloc_addr(vaddr))
312 d_page->p = vmalloc_to_page(vaddr);
313 else
314 d_page->p = virt_to_page(vaddr);
Christoph was explaining this earlier and I don't think it's sufficient
to just check is_vmalloc_addr(). See https://lkml.org/lkml/2019/6/17/155
Apparently the vaddr might not have a page backing...
(I am a newbie to this so I may be wrong or have misunderstood also).
315 d_page->vaddr = (unsigned long)vaddr;
316 if (pool->type & IS_HUGE)
317 d_page->vaddr |= VADDR_FLAG_HUGE_POOL;
318 } else {
319 kfree(d_page);
320 d_page = NULL;
321 }
322 return d_page;
323 }
regards,
dan carpenter
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