Re: [PATCH 14/22] drm/i915: Allocate error capture in atomic context

On Mon, Aug 16, 2021 at 06:51:31AM -0700, Matthew Brost wrote:

Error captures can now be done in a work queue processing G2H messages. These messages need to be completely done being processed in the reset path, to avoid races in the missing G2H cleanup, which create a dependency on memory allocations and dma fences (i915_requests). Requests depend on resets, thus now we have a circular dependency. To work around this, allocate the error capture in an atomic context.

Fixes: dc0dad365c5e ("Fix for error capture after full GPU reset with GuC") Fixes: 573ba126aef3 ("Capture error state on context reset") Signed-off-by: Matthew Brost matthew.brost@intel.com

---

drivers/gpu/drm/i915/i915_gpu_error.c | 37 +++++++++++++-------------- 1 file changed, 18 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c index 0f08bcfbe964..453376aa6d9f 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -49,7 +49,6 @@ #include "i915_memcpy.h" #include "i915_scatterlist.h"

-#define ALLOW_FAIL (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN) #define ATOMIC_MAYFAIL (GFP_ATOMIC | __GFP_NOWARN)

This one doesn't make much sense. GFP_ATOMIC essentially means we're high-priority and failure would be a pretty bad day. Meanwhile __GFP_NOWARN means we can totally cope with failure, pls don't holler.

GFP_NOWAIT | __GFP_NOWARN would the more consistent one here I think.

gfp.h for all the docs for this.

Separate patch ofc. This one is definitely the right direction, since GFP_KERNEL from the reset worker is not a good idea. -Daniel

static void __sg_set_buf(struct scatterlist *sg, @@ -79,7 +78,7 @@ static bool __i915_error_grow(struct drm_i915_error_state_buf *e, size_t len) if (e->cur == e->end) { struct scatterlist *sgl;

• sgl = (typeof(sgl))__get_free_page(ALLOW_FAIL);
  

• sgl = (typeof(sgl))__get_free_page(ATOMIC_MAYFAIL);
  

  if (!sgl) { e->err = -ENOMEM; return false;

@@ -99,10 +98,10 @@ static bool __i915_error_grow(struct drm_i915_error_state_buf *e, size_t len) }

e->size = ALIGN(len + 1, SZ_64K);

• e->buf = kmalloc(e->size, ALLOW_FAIL);

• e->buf = kmalloc(e->size, ATOMIC_MAYFAIL); if (!e->buf) { e->size = PAGE_ALIGN(len + 1);

• e->buf = kmalloc(e->size, GFP_KERNEL);
  

• e->buf = kmalloc(e->size, ATOMIC_MAYFAIL);
  

  } if (!e->buf) { e->err = -ENOMEM;

@@ -243,12 +242,12 @@ static bool compress_init(struct i915_vma_compress *c) { struct z_stream_s *zstream = &c->zstream;

• if (pool_init(&c->pool, ALLOW_FAIL))

• if (pool_init(&c->pool, ATOMIC_MAYFAIL)) return false;

  zstream->workspace = kmalloc(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),

• 	ALLOW_FAIL);
  

• 	ATOMIC_MAYFAIL);
  

  if (!zstream->workspace) { pool_fini(&c->pool); return false;

@@ -256,7 +255,7 @@ static bool compress_init(struct i915_vma_compress *c)

c->tmp = NULL; if (i915_has_memcpy_from_wc())

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

• c->tmp = pool_alloc(&c->pool, ATOMIC_MAYFAIL);
  
  

  return true;

} @@ -280,7 +279,7 @@ static void *compress_next_page(struct i915_vma_compress *c, if (dst->page_count >= dst->num_pages) return ERR_PTR(-ENOSPC);

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

• page = pool_alloc(&c->pool, ATOMIC_MAYFAIL); if (!page) return ERR_PTR(-ENOMEM);

@@ -376,7 +375,7 @@ struct i915_vma_compress {

static bool compress_init(struct i915_vma_compress *c) {

• return pool_init(&c->pool, ALLOW_FAIL) == 0;

• return pool_init(&c->pool, ATOMIC_MAYFAIL) == 0;

}

static bool compress_start(struct i915_vma_compress *c) @@ -391,7 +390,7 @@ static int compress_page(struct i915_vma_compress *c, { void *ptr;

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

• ptr = pool_alloc(&c->pool, ATOMIC_MAYFAIL); if (!ptr) return -ENOMEM;

@@ -997,7 +996,7 @@ i915_vma_coredump_create(const struct intel_gt *gt,

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) + num_pages * sizeof(u32 *), ATOMIC_MAYFAIL); if (!dst) return NULL;

@@ -1433,7 +1432,7 @@ capture_engine(struct intel_engine_cs *engine, struct i915_request *rq = NULL; unsigned long flags;

• ee = intel_engine_coredump_alloc(engine, GFP_KERNEL);

• ee = intel_engine_coredump_alloc(engine, ATOMIC_MAYFAIL); if (!ee) return NULL;

@@ -1481,7 +1480,7 @@ gt_record_engines(struct intel_gt_coredump *gt, struct intel_engine_coredump *ee;

/* Refill our page pool before entering atomic section */

• pool_refill(&compress->pool, ALLOW_FAIL);
  

• pool_refill(&compress->pool, ATOMIC_MAYFAIL);
  
  

  ee = capture_engine(engine, compress); if (!ee)

@@ -1507,7 +1506,7 @@ gt_record_uc(struct intel_gt_coredump *gt, const struct intel_uc *uc = &gt->_gt->uc; struct intel_uc_coredump *error_uc;

• error_uc = kzalloc(sizeof(*error_uc), ALLOW_FAIL);

• error_uc = kzalloc(sizeof(*error_uc), ATOMIC_MAYFAIL); if (!error_uc) return NULL;

@@ -1518,8 +1517,8 @@ gt_record_uc(struct intel_gt_coredump *gt, * As modparams are generally accesible from the userspace make * explicit copies of the firmware paths. */

• error_uc->guc_fw.path = kstrdup(uc->guc.fw.path, ALLOW_FAIL);
• error_uc->huc_fw.path = kstrdup(uc->huc.fw.path, ALLOW_FAIL);

• error_uc->guc_fw.path = kstrdup(uc->guc.fw.path, ATOMIC_MAYFAIL);
• error_uc->huc_fw.path = kstrdup(uc->huc.fw.path, ATOMIC_MAYFAIL); error_uc->guc_log = i915_vma_coredump_create(gt->_gt, uc->guc.log.vma, "GuC log buffer",

@@ -1778,7 +1777,7 @@ i915_vma_capture_prepare(struct intel_gt_coredump *gt) { struct i915_vma_compress *compress;

• compress = kmalloc(sizeof(*compress), ALLOW_FAIL);

• compress = kmalloc(sizeof(*compress), ATOMIC_MAYFAIL); if (!compress) return NULL;

@@ -1811,11 +1810,11 @@ i915_gpu_coredump(struct intel_gt *gt, intel_engine_mask_t engine_mask) if (IS_ERR(error)) return error;

• error = i915_gpu_coredump_alloc(i915, ALLOW_FAIL);

• error = i915_gpu_coredump_alloc(i915, ATOMIC_MAYFAIL); if (!error) return ERR_PTR(-ENOMEM);

• error->gt = intel_gt_coredump_alloc(gt, ALLOW_FAIL);

• error->gt = intel_gt_coredump_alloc(gt, ATOMIC_MAYFAIL); if (error->gt) { struct i915_vma_compress *compress;

-- 2.32.0