Commit 591711b3 authored May 08, 2026 by Thomas Hellström

drm/ttm: Convert -EAGAIN from dmem_cgroup_try_charge to -ENOSPC



dmem_cgroup_try_charge() returns -EAGAIN when the cgroup limit is
hit and the charge fails. TTM has no concept of -EAGAIN from resource
allocation; -ENOSPC is the canonical error meaning "no space, try
eviction". Convert at the source in ttm_resource_alloc() so no caller
needs to handle an unexpected error code, and clean up the now-redundant
-EAGAIN check in ttm_bo_alloc_resource().

Without this, -EAGAIN escaping ttm_resource_alloc() during an eviction
walk causes the walk to terminate early instead of continuing to the
next candidate.

Cc: Friedrich Vock <friedrich.vock@gmx.de>
Cc: Maarten Lankhorst <dev@lankhorst.se>
Cc: Tejun Heo <tj@kernel.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.14+
Fixes: 2b624a2c ("drm/ttm: Handle cgroup based eviction in TTM")
Assisted-by: GitHub_Copilot:claude-sonnet-4.6
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Maarten Lankhorst <dev@lankhrost.se>
Link: https://patch.msgid.link/20260508160920.230339-1-thomas.hellstrom@linux.intel.com

parent 84d1c9b4

drivers/gpu/drm/ttm/ttm_bo.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -739,7 +739,7 @@ static int ttm_bo_alloc_resource(struct ttm_buffer_object *bo,
		may_evict = (force_space && place->mem_type != TTM_PL_SYSTEM);
		ret = ttm_resource_alloc(bo, place, res, force_space ? &limit_pool : NULL);
		if (ret) {
		if (ret != -ENOSPC && ret != -EAGAIN) {
		if (ret != -ENOSPC) {
		dmem_cgroup_pool_state_put(limit_pool);
		return ret;
		}

drivers/gpu/drm/ttm/ttm_resource.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -398,9 +398,12 @@ int ttm_resource_alloc(struct ttm_buffer_object *bo,

		if (man->cg) {
		ret = dmem_cgroup_try_charge(man->cg, bo->base.size, &pool, ret_limit_pool);
		if (ret)
		if (ret) {
		if (ret == -EAGAIN)
		ret = -ENOSPC;
		return ret;
		}
		}

		ret = man->func->alloc(man, bo, place, res_ptr);
		if (ret) {