Commit e45b98ba authored by Thomas Hellström's avatar Thomas Hellström
Browse files

drm/i915: Avoid allocating a page array for the gpu coredump 



The gpu coredump typically takes place in a dma_fence signalling
critical path, and hence can't use GFP_KERNEL allocations, as that
means we might hit deadlocks under memory pressure. However
changing to __GFP_KSWAPD_RECLAIM which will be done in an upcoming
patch will instead mean a lower chance of the allocation succeeding.
In particular large contigous allocations like the coredump page
vector.
Remove the page vector in favor of a linked list of single pages.
Use the page lru list head as the list link, as the page owner is
allowed to do that.

Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarRamalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211108174547.979714-2-thomas.hellstrom@linux.intel.com
parent 5c2625c4

drivers/gpu/drm/i915/i915_gpu_error.c

+27 −23
Original line number Diff line number Diff line
@@ -275,16 +275,16 @@ static bool compress_start(struct i915_vma_compress *c) 
static void *compress_next_page(struct i915_vma_compress *c,

				struct i915_vma_coredump *dst)

{

	void *page;



	if (dst->page_count >= dst->num_pages)

		return ERR_PTR(-ENOSPC);

	void *page_addr;

	struct page *page;



	page = pool_alloc(&c->pool, ALLOW_FAIL);

	if (!page)

	page_addr = pool_alloc(&c->pool, ALLOW_FAIL);

	if (!page_addr)

		return ERR_PTR(-ENOMEM);



	return dst->pages[dst->page_count++] = page;

	page = virt_to_page(page_addr);

	list_add_tail(&page->lru, &dst->page_list);

	return page_addr;

}



static int compress_page(struct i915_vma_compress *c,
@@ -397,7 +397,7 @@ static int compress_page(struct i915_vma_compress *c, 


	if (!(wc && i915_memcpy_from_wc(ptr, src, PAGE_SIZE)))

		memcpy(ptr, src, PAGE_SIZE);

	dst->pages[dst->page_count++] = ptr;

	list_add_tail(&virt_to_page(ptr)->lru, &dst->page_list);

	cond_resched();



	return 0;
@@ -614,7 +614,7 @@ static void print_error_vma(struct drm_i915_error_state_buf *m, 
			    const struct i915_vma_coredump *vma)

{

	char out[ASCII85_BUFSZ];

	int page;

	struct page *page;



	if (!vma)

		return;
@@ -628,16 +628,17 @@ static void print_error_vma(struct drm_i915_error_state_buf *m, 
		err_printf(m, "gtt_page_sizes = 0x%08x\n", vma->gtt_page_sizes);



	err_compression_marker(m);

	for (page = 0; page < vma->page_count; page++) {

	list_for_each_entry(page, &vma->page_list, lru) {

		int i, len;

		const u32 *addr = page_address(page);



		len = PAGE_SIZE;

		if (page == vma->page_count - 1)

		if (page == list_last_entry(&vma->page_list, typeof(*page), lru))

			len -= vma->unused;

		len = ascii85_encode_len(len);



		for (i = 0; i < len; i++)

			err_puts(m, ascii85_encode(vma->pages[page][i], out));

			err_puts(m, ascii85_encode(addr[i], out));

	}

	err_puts(m, "\n");

}
@@ -946,10 +947,12 @@ static void i915_vma_coredump_free(struct i915_vma_coredump *vma) 
{

	while (vma) {

		struct i915_vma_coredump *next = vma->next;

		int page;

		struct page *page, *n;



		for (page = 0; page < vma->page_count; page++)

			free_page((unsigned long)vma->pages[page]);

		list_for_each_entry_safe(page, n, &vma->page_list, lru) {

			list_del_init(&page->lru);

			__free_page(page);

		}



		kfree(vma);

		vma = next;
@@ -1016,7 +1019,6 @@ i915_vma_coredump_create(const struct intel_gt *gt, 
	struct i915_ggtt *ggtt = gt->ggtt;

	const u64 slot = ggtt->error_capture.start;

	struct i915_vma_coredump *dst;

	unsigned long num_pages;

	struct sgt_iter iter;

	int ret;
@@ -1025,9 +1027,7 @@ i915_vma_coredump_create(const struct intel_gt *gt, 
	if (!vma || !vma->pages || !compress)

		return NULL;



	num_pages = min_t(u64, vma->size, vma->obj->base.size) >> PAGE_SHIFT;

	num_pages = DIV_ROUND_UP(10 * num_pages, 8); /* worstcase zlib growth */

	dst = kmalloc(sizeof(*dst) + num_pages * sizeof(u32 *), ALLOW_FAIL);

	dst = kmalloc(sizeof(*dst), ALLOW_FAIL);

	if (!dst)

		return NULL;
@@ -1036,14 +1036,13 @@ i915_vma_coredump_create(const struct intel_gt *gt, 
		return NULL;

	}



	INIT_LIST_HEAD(&dst->page_list);

	strcpy(dst->name, name);

	dst->next = NULL;



	dst->gtt_offset = vma->node.start;

	dst->gtt_size = vma->node.size;

	dst->gtt_page_sizes = vma->page_sizes.gtt;

	dst->num_pages = num_pages;

	dst->page_count = 0;

	dst->unused = 0;



	ret = -EINVAL;
@@ -1106,8 +1105,13 @@ i915_vma_coredump_create(const struct intel_gt *gt, 
	}



	if (ret || compress_flush(compress, dst)) {

		while (dst->page_count--)

			pool_free(&compress->pool, dst->pages[dst->page_count]);

		struct page *page, *n;



		list_for_each_entry_safe_reverse(page, n, &dst->page_list, lru) {

			list_del_init(&page->lru);

			pool_free(&compress->pool, page_address(page));

		}



		kfree(dst);

		dst = NULL;

	}

drivers/gpu/drm/i915/i915_gpu_error.h

+1 −3
Original line number Diff line number Diff line
@@ -39,10 +39,8 @@ struct i915_vma_coredump { 
	u64 gtt_size;

	u32 gtt_page_sizes;



	int num_pages;

	int page_count;

	int unused;

	u32 *pages[];

	struct list_head page_list;

};



struct i915_request_coredump {