Re: [Intel-gfx] [PATCH 16/27] drm/i915: Allocate error capture in nowait context

On Wed, Aug 25, 2021 at 08:23:16PM -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 a nowait context.

v2: (Daniel Vetter)

• Use GFP_NOWAIT instead GFP_ATOMIC

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

Would be good to include an example splat here, since memory inversions are a bit wtf due to the fake lockdep locks involved. In generally always good to put all the data you have into the commit message (maybe condensed down) so it's easier to dig out things again.

With that: Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

---

drivers/gpu/drm/i915/i915_gpu_error.c | 39 +++++++++++++-------------- 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c index b9f66dbd46bb..8696ead02118 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -49,8 +49,7 @@ #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) +#define ATOMIC_MAYFAIL (GFP_NOWAIT | __GFP_NOWARN)

static void __sg_set_buf(struct scatterlist *sg, void *addr, unsigned int len, loff_t it) @@ -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;

@@ -1026,7 +1025,7 @@ 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;

@@ -1462,7 +1461,7 @@ 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;

@@ -1510,7 +1509,7 @@ 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)

@@ -1536,7 +1535,7 @@ 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;

@@ -1547,8 +1546,8 @@ 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",

@@ -1815,7 +1814,7 @@ 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;

@@ -1848,11 +1847,11 @@ 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