Re: [PATCH 3/5] drm/ttm: add ttm page_flags TTM_PAGE_FLAG_PAGEFAULT

Christian König <christian.koenig@xxxxxxx> · Fri, 2 Feb 2018 08:42:01 +0100

Am 02.02.2018 um 08:22 schrieb Roger He:
to indicate whether we are servicing for page fault routine in
ttm_mem_global_reserve.

for ttm_mem_global_reserve if in page fault routine, allow success
always. because page fault routing already grabbed system memory
successfully and allow this exception is harmless.
Otherwise, it will trigger OOM killer.

v2: fix minor typo
v3: keep original behavior except ttm page with flag NO_RETRY

We need to extend this to the suspend/resume case as well.

Saying so would it be possible to make that behavior depend on the ctx 
instead of the page flags?

Thanks,
Christian.


Signed-off-by: Roger He <Hongbo.He@xxxxxxx>
---
  drivers/gpu/drm/ttm/ttm_bo_vm.c          |  6 +++++-
  drivers/gpu/drm/ttm/ttm_memory.c         | 27 +++++++++++++++++++--------
  drivers/gpu/drm/ttm/ttm_page_alloc.c     |  5 ++++-
  drivers/gpu/drm/ttm/ttm_page_alloc_dma.c |  9 ++++++---
  drivers/gpu/drm/ttm/ttm_tt.c             |  2 +-
  include/drm/ttm/ttm_bo_driver.h          |  1 +
  include/drm/ttm/ttm_memory.h             |  3 ++-
  7 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 716e724..f03dd94 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -233,8 +233,12 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf)
  		cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
  						cvma.vm_page_prot);
  
+		if (ttm->page_flags & TTM_PAGE_FLAG_NO_RETRY)
+			ttm->page_flags |= TTM_PAGE_FLAG_PAGEFAULT;
  		/* Allocate all page at once, most common usage */
-		if (ttm->bdev->driver->ttm_tt_populate(ttm, &ctx)) {
+		ret = ttm->bdev->driver->ttm_tt_populate(ttm, &ctx);
+		ttm->page_flags &= ~TTM_PAGE_FLAG_PAGEFAULT;
+		if (ret) {
  			ret = VM_FAULT_OOM;
  			goto out_io_unlock;
  		}
diff --git a/drivers/gpu/drm/ttm/ttm_memory.c b/drivers/gpu/drm/ttm/ttm_memory.c
index 598b14b..f5227a5 100644
--- a/drivers/gpu/drm/ttm/ttm_memory.c
+++ b/drivers/gpu/drm/ttm/ttm_memory.c
@@ -472,7 +472,8 @@ EXPORT_SYMBOL(ttm_mem_global_free);
  
  static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
  				  struct ttm_mem_zone *single_zone,
-				  uint64_t amount, bool reserve)
+				  uint64_t amount, bool reserve,
+				  bool in_pagefault)
  {
  	uint64_t free_swap_mem = get_nr_swap_pages() << (PAGE_SHIFT - 1);
  	uint64_t swap_glob_mem, limit, total_used_mem;
@@ -483,6 +484,13 @@ static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
  	swap_glob_mem = atomic64_read(&glob->swap_glob_mem);
  
  	spin_lock(&glob->lock);
+	/*
+	 * if in page_fault allow reserve successfully anyway since it
+	 * already allocated system pages. Otherwise it will trigger OOM
+	 */
+	if (in_pagefault)
+		goto reserve_direct;
+
  	/* adjust the max_swap_mem to cover the new inserted swap space */
  	if (glob->max_swap_mem < free_swap_mem)
  		glob->max_swap_mem = free_swap_mem;
@@ -501,6 +509,7 @@ static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
  			goto out_unlock;
  	}
  
+reserve_direct:
  	if (reserve) {
  		for (i = 0; i < glob->num_zones; ++i) {
  			zone = glob->zones[i];
@@ -522,13 +531,13 @@ static int ttm_mem_global_reserve(struct ttm_mem_global *glob,
  static int ttm_mem_global_alloc_zone(struct ttm_mem_global *glob,
  				     struct ttm_mem_zone *single_zone,
  				     uint64_t memory,
-				     struct ttm_operation_ctx *ctx)
+				     struct ttm_operation_ctx *ctx,
+				     bool in_pagefault)
  {
  	int count = TTM_MEMORY_ALLOC_RETRIES;
  
-	while (unlikely(ttm_mem_global_reserve(glob,
-					       single_zone,
-					       memory, true)
+	while (unlikely(ttm_mem_global_reserve(glob, single_zone, memory,
+					       true, in_pagefault)
  			!= 0)) {
  		if (ctx->no_wait_gpu)
  			return -ENOMEM;
@@ -548,13 +557,14 @@ int ttm_mem_global_alloc(struct ttm_mem_global *glob, uint64_t memory,
  	 * all zones.
  	 */
  
-	return ttm_mem_global_alloc_zone(glob, NULL, memory, ctx);
+	return ttm_mem_global_alloc_zone(glob, NULL, memory, ctx, false);
  }
  EXPORT_SYMBOL(ttm_mem_global_alloc);
  
  int ttm_mem_global_alloc_page(struct ttm_mem_global *glob,
  			      struct page *page, uint64_t size,
-			      struct ttm_operation_ctx *ctx)
+			      struct ttm_operation_ctx *ctx,
+			      bool in_pagefault)
  {
  	struct ttm_mem_zone *zone = NULL;
  
@@ -570,7 +580,8 @@ int ttm_mem_global_alloc_page(struct ttm_mem_global *glob,
  	if (glob->zone_dma32 && page_to_pfn(page) > 0x00100000UL)
  		zone = glob->zone_kernel;
  #endif
-	return ttm_mem_global_alloc_zone(glob, zone, size, ctx);
+	return ttm_mem_global_alloc_zone(glob, zone, size,
+					 ctx, in_pagefault);
  }
  
  void ttm_mem_global_free_page(struct ttm_mem_global *glob, struct page *page,
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index 5edcd89..15bf691 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -1094,6 +1094,7 @@ ttm_pool_unpopulate_helper(struct ttm_tt *ttm, unsigned mem_count_update)
  int ttm_pool_populate(struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
  {
  	struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
+	bool in_pagefault;
  	unsigned i;
  	int ret;
  
@@ -1107,9 +1108,11 @@ int ttm_pool_populate(struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
  		return ret;
  	}
  
+	in_pagefault = ttm->page_flags & TTM_PAGE_FLAG_PAGEFAULT;
  	for (i = 0; i < ttm->num_pages; ++i) {
  		ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
-						PAGE_SIZE, ctx);
+						PAGE_SIZE, ctx,
+						in_pagefault);
  		if (unlikely(ret != 0)) {
  			ttm_pool_unpopulate_helper(ttm, i);
  			return -ENOMEM;
diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
index b122f6e..b8adf37 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc_dma.c
@@ -934,6 +934,7 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
  	struct dma_pool *pool;
  	struct dma_page *d_page;
  	enum pool_type type;
+	bool in_pagefault;
  	unsigned i;
  	int ret;
  
@@ -943,8 +944,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
  	INIT_LIST_HEAD(&ttm_dma->pages_list);
  	i = 0;
  
+	in_pagefault = ttm_dma->ttm.page_flags & TTM_PAGE_FLAG_PAGEFAULT;
  	type = ttm_to_type(ttm->page_flags, ttm->caching_state);
-
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  	if (ttm->page_flags & TTM_PAGE_FLAG_DMA32)
  		goto skip_huge;
@@ -966,7 +967,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
  			break;
  
  		ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
-						pool->size, ctx);
+						pool->size, ctx,
+						in_pagefault);
  		if (unlikely(ret != 0)) {
  			ttm_dma_unpopulate(ttm_dma, dev);
  			return -ENOMEM;
@@ -1003,7 +1005,8 @@ int ttm_dma_populate(struct ttm_dma_tt *ttm_dma, struct device *dev,
  		}
  
  		ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
-						pool->size, ctx);
+						pool->size, ctx,
+						in_pagefault);
  		if (unlikely(ret != 0)) {
  			ttm_dma_unpopulate(ttm_dma, dev);
  			return -ENOMEM;
diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 5d441e0..a730cd6 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -391,7 +391,7 @@ int ttm_tt_swapout(struct ttm_tt *ttm, struct file *persistent_swap_storage)
  		ttm->page_flags |= TTM_PAGE_FLAG_PERSISTENT_SWAP;
  	else
  		atomic64_add_return(ttm->num_pages << PAGE_SHIFT,
-			    &ttm->glob->mem_glob->swap_glob_mem);
+				    &ttm->glob->mem_glob->swap_glob_mem);
  
  	return 0;
  out_err:
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 9b417eb..8f68781 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -87,6 +87,7 @@ struct ttm_backend_func {
  #define TTM_PAGE_FLAG_DMA32           (1 << 7)
  #define TTM_PAGE_FLAG_SG              (1 << 8)
  #define TTM_PAGE_FLAG_NO_RETRY	      (1 << 9)
+#define TTM_PAGE_FLAG_PAGEFAULT       (1 << 10)
  
  enum ttm_caching_state {
  	tt_uncached,
diff --git a/include/drm/ttm/ttm_memory.h b/include/drm/ttm/ttm_memory.h
index 6282b50..6c29b5c 100644
--- a/include/drm/ttm/ttm_memory.h
+++ b/include/drm/ttm/ttm_memory.h
@@ -89,7 +89,8 @@ extern void ttm_mem_global_free(struct ttm_mem_global *glob,
  				uint64_t amount);
  extern int ttm_mem_global_alloc_page(struct ttm_mem_global *glob,
  				     struct page *page, uint64_t size,
-				     struct ttm_operation_ctx *ctx);
+				     struct ttm_operation_ctx *ctx,
+				     bool in_pagefault);
  extern void ttm_mem_global_free_page(struct ttm_mem_global *glob,
  				     struct page *page, uint64_t size);
  extern size_t ttm_round_pot(size_t size);

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