From: Lu Baolu <baolu.lu@linux.intel.com>
To: Qian Cai <cai@lca.pw>, jroedel@suse.de
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/vt-d: silence a RCU-list debugging warning
Date: Wed, 18 Mar 2020 13:27:53 +0800 [thread overview]
Message-ID: <36b9e69b-ee3f-c17d-1788-64448ce8bc14@linux.intel.com> (raw)
In-Reply-To: <20200317150326.1659-1-cai@lca.pw>
On 2020/3/17 23:03, Qian Cai wrote:
> dmar_find_atsr() calls list_for_each_entry_rcu() outside of an RCU read
> side critical section but with dmar_global_lock held. Silence this
> false positive.
>
> drivers/iommu/intel-iommu.c:4504 RCU-list traversed in non-reader section!!
> 1 lock held by swapper/0/1:
> #0: ffffffff9755bee8 (dmar_global_lock){+.+.}, at: intel_iommu_init+0x1a6/0xe19
>
> Call Trace:
> dump_stack+0xa4/0xfe
> lockdep_rcu_suspicious+0xeb/0xf5
> dmar_find_atsr+0x1ab/0x1c0
> dmar_parse_one_atsr+0x64/0x220
> dmar_walk_remapping_entries+0x130/0x380
> dmar_table_init+0x166/0x243
> intel_iommu_init+0x1ab/0xe19
> pci_iommu_init+0x1a/0x44
> do_one_initcall+0xae/0x4d0
> kernel_init_freeable+0x412/0x4c5
> kernel_init+0x19/0x193
>
> Signed-off-by: Qian Cai <cai@lca.pw>
How about changing the commit subject to
"iommu/vt-d: Silence RCU-list debugging warning in dmar_find_atsr()"?
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Best regards,
baolu
> ---
> 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 4be549478691..ef0a5246700e 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -4501,7 +4501,8 @@ static struct dmar_atsr_unit *dmar_find_atsr(struct acpi_dmar_atsr *atsr)
> struct dmar_atsr_unit *atsru;
> struct acpi_dmar_atsr *tmp;
>
> - list_for_each_entry_rcu(atsru, &dmar_atsr_units, list) {
> + list_for_each_entry_rcu(atsru, &dmar_atsr_units, list,
> + dmar_rcu_check()) {
> tmp = (struct acpi_dmar_atsr *)atsru->hdr;
> if (atsr->segment != tmp->segment)
> continue;
>
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next prev parent reply other threads:[~2020-03-18 5:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 15:03 [PATCH] iommu/vt-d: silence a RCU-list debugging warning Qian Cai
2020-03-18 5:27 ` Lu Baolu [this message]
2020-03-18 11:14 ` Qian Cai
2020-03-19 14:16 ` Joerg Roedel
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