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Thu, 20 Feb 2025 02:15:37 -0800 (PST) From: Yunhui Cui To: dwmw2@infradead.org, baolu.lu@linux.intel.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Yunhui Cui Subject: [PATCH] iommu/vt-d: fix system hang on reboot -f Date: Thu, 20 Feb 2025 18:15:11 +0800 Message-Id: <20250220101511.37602-1-cuiyunhui@bytedance.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When entering intel_iommu_shutdown, system interrupts are disabled, and the reboot process might be scheduled out by down_write(). If the scheduled process does not yield (e.g., while(1)), the system will hang. Signed-off-by: Yunhui Cui --- drivers/iommu/intel/iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index cc46098f875b..76a1d83b46bf 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -2871,7 +2871,8 @@ void intel_iommu_shutdown(void) if (no_iommu || dmar_disabled) return; =20 - down_write(&dmar_global_lock); + if (!down_write_trylock(&dmar_global_lock)) + return; =20 /* Disable PMRs explicitly here. */ for_each_iommu(iommu, drhd) --=20 2.39.2