Patch "drm/ttm: Convert -EAGAIN from dmem_cgroup_try_charge to -ENOSPC" has been added to the 6.18-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 6.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-ttm-convert-eagain-from-dmem_cgroup_try_charge-to-enospc.patch
and it can be found in the queue-6.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From 591711b32681a04b57d00c2a404658f8419a081c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= <thomas.hellstrom@linux.intel.com>
Date: Fri, 8 May 2026 18:09:20 +0200
Subject: drm/ttm: Convert -EAGAIN from dmem_cgroup_try_charge to -ENOSPC
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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From: Thomas Hellström <thomas.hellstrom@linux.intel.com>

commit 591711b32681a04b57d00c2a404658f8419a081c upstream.

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: 2b624a2c1865 ("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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/ttm/ttm_bo.c       |    2 +-
 drivers/gpu/drm/ttm/ttm_resource.c |    5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -739,7 +739,7 @@ static int ttm_bo_alloc_resource(struct
 		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;
 			}
--- a/drivers/gpu/drm/ttm/ttm_resource.c
+++ b/drivers/gpu/drm/ttm/ttm_resource.c
@@ -384,8 +384,11 @@ int ttm_resource_alloc(struct ttm_buffer
 
 	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);


Patches currently in stable-queue which might be from thomas.hellstrom@linux.intel.com are

queue-6.18/drm-xe-dma-buf-fix-uaf-with-retry-loop.patch
queue-6.18/drm-xe-dma-buf-handle-empty-bo-and-uaf-races.patch
queue-6.18/drm-ttm-convert-eagain-from-dmem_cgroup_try_charge-to-enospc.patch