linux-kernel - [PATCH AUTOSEL 6.12 439/486] drm/xe/relay: Don't use GFP

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Message-Id: <20250505223922.2682012-439-sashal@kernel.org>
Date: Mon,  5 May 2025 18:38:35 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Michal Wajdeczko <michal.wajdeczko@...el.com>,
	Marcin Bernatowicz <marcin.bernatowicz@...ux.intel.com>,
	Sasha Levin <sashal@...nel.org>,
	lucas.demarchi@...el.com,
	thomas.hellstrom@...ux.intel.com,
	rodrigo.vivi@...el.com,
	airlied@...il.com,
	simona@...ll.ch,
	intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.12 439/486] drm/xe/relay: Don't use GFP_KERNEL for new transactions

From: Michal Wajdeczko <michal.wajdeczko@...el.com>

[ Upstream commit 78d5d1e20d1de9422f013338a0f2311448588ba7 ]

VFs use a relay transaction during the resume/reset flow and use
of the GFP_KERNEL flag may conflict with the reclaim:

     -> #0 (fs_reclaim){+.+.}-{0:0}:
 [ ]        __lock_acquire+0x1874/0x2bc0
 [ ]        lock_acquire+0xd2/0x310
 [ ]        fs_reclaim_acquire+0xc5/0x100
 [ ]        mempool_alloc_noprof+0x5c/0x1b0
 [ ]        __relay_get_transaction+0xdc/0xa10 [xe]
 [ ]        relay_send_to+0x251/0xe50 [xe]
 [ ]        xe_guc_relay_send_to_pf+0x79/0x3a0 [xe]
 [ ]        xe_gt_sriov_vf_connect+0x90/0x4d0 [xe]
 [ ]        xe_uc_init_hw+0x157/0x3b0 [xe]
 [ ]        do_gt_restart+0x1ae/0x650 [xe]
 [ ]        xe_gt_resume+0xb6/0x120 [xe]
 [ ]        xe_pm_runtime_resume+0x15b/0x370 [xe]
 [ ]        xe_pci_runtime_resume+0x73/0x90 [xe]
 [ ]        pci_pm_runtime_resume+0xa0/0x100
 [ ]        __rpm_callback+0x4d/0x170
 [ ]        rpm_callback+0x64/0x70
 [ ]        rpm_resume+0x594/0x790
 [ ]        __pm_runtime_resume+0x4e/0x90
 [ ]        xe_pm_runtime_get_ioctl+0x9c/0x160 [xe]

Since we have a preallocated pool of relay transactions, which
should cover all our normal relay use cases, we may use the
GFP_NOWAIT flag when allocating new outgoing transactions.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@...el.com>
Tested-by: Marcin Bernatowicz <marcin.bernatowicz@...ux.intel.com>
Reviewed-by: Marcin Bernatowicz <marcin.bernatowicz@...ux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250131153713.808-1-michal.wajdeczko@intel.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/xe/xe_guc_relay.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_relay.c b/drivers/gpu/drm/xe/xe_guc_relay.c
index ade6162dc2598..0e5b43e1518ea 100644
--- a/drivers/gpu/drm/xe/xe_guc_relay.c
+++ b/drivers/gpu/drm/xe/xe_guc_relay.c
@@ -224,7 +224,7 @@ __relay_get_transaction(struct xe_guc_relay *relay, bool incoming, u32 remote, u
 	 * with CTB lock held which is marked as used in the reclaim path.
 	 * Btw, that's one of the reason why we use mempool here!
 	 */
-	txn = mempool_alloc(&relay->pool, incoming ? GFP_ATOMIC : GFP_KERNEL);
+	txn = mempool_alloc(&relay->pool, incoming ? GFP_ATOMIC : GFP_NOWAIT);
 	if (!txn)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.39.5