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 <[email protected]>
---
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;
--
2.21.0 (Apple Git-122.2)
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 <[email protected]>
How about changing the commit subject to
"iommu/vt-d: Silence RCU-list debugging warning in dmar_find_atsr()"?
Acked-by: Lu Baolu <[email protected]>
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;
>
> On Mar 18, 2020, at 1:27 AM, Lu Baolu <[email protected]> wrote:
>
> How about changing the commit subject to
> "iommu/vt-d: Silence RCU-list debugging warning in dmar_find_atsr()"?
Just a bit long which should be non-issue.
On Wed, Mar 18, 2020 at 01:27:53PM +0800, Lu Baolu wrote:
> 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 <[email protected]>
>
> How about changing the commit subject to
> "iommu/vt-d: Silence RCU-list debugging warning in dmar_find_atsr()"?
>
> Acked-by: Lu Baolu <[email protected]>
Fixed up the subject and applied it, thanks.