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@xxxxxxxxx>
> ---
> 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->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
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
