From e45b98ba627691c6b577244abfdb18ef2621fea3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= Date: Mon, 8 Nov 2021 18:45:44 +0100 Subject: [PATCH] drm/i915: Avoid allocating a page array for the gpu coredump MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Thomas Hellström Reviewed-by: Ramalingam C Link: https://patchwork.freedesktop.org/patch/msgid/20211108174547.979714-2-thomas.hellstrom@linux.intel.com --- drivers/gpu/drm/i915/i915_gpu_error.c | 50 +++++++++++++++------------ drivers/gpu/drm/i915/i915_gpu_error.h | 4 +-- 2 files changed, 28 insertions(+), 26 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c index 2a2d7643b551..14de64282697 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -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; + void *page_addr; + struct page *page; - if (dst->page_count >= dst->num_pages) - return ERR_PTR(-ENOSPC); - - 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; } diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h index b98d8cdbe4f2..5aedf5129814 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.h +++ b/drivers/gpu/drm/i915/i915_gpu_error.h @@ -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 {