On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
>This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
>
>This change introduces a regression on Alder Lake that completely
>blocks testing. To enable CI and avoid possible circular locking
>warning, revert the patch.
We are already on rc5. Are iommu authors involved aware of this issue?
We could do this in our "for CI only" branch, but it's equally important
that this is fixed for 6.0
Cc'ing them.
thanks
Lucas De Marchi
>
>kernel log:
>
>======================================================
>WARNING: possible circular locking dependency detected
>6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
>------------------------------------------------------
>cpuhp/0/15 is trying to acquire lock:
>ffff8881013df278 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x20/0x50
> but task is already holding lock:
>ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x48/0x1f0
> which lock already depends on the new loc
> the existing dependency chain (in reverse order) is:
> -> #3 (cpuhp_state-up){+.+.}-{0:0}:
> lock_acquire+0xd3/0x310
> cpuhp_thread_fun+0xa6/0x1f0
> smpboot_thread_fn+0x1b5/0x260
> kthread+0xed/0x120
> ret_from_fork+0x1f/0x30
> -> #2 (cpu_hotplug_lock){++++}-{0:0}:
> lock_acquire+0xd3/0x310
> __cpuhp_state_add_instance+0x43/0x1c0
> iova_domain_init_rcaches+0x199/0x1c0
> iommu_setup_dma_ops+0x130/0x440
> bus_iommu_probe+0x26a/0x2d0
> bus_set_iommu+0x82/0xd0
> intel_iommu_init+0xe33/0x1039
> pci_iommu_init+0x9/0x31
> do_one_initcall+0x53/0x2f0
> kernel_init_freeable+0x18f/0x1e1
> kernel_init+0x11/0x120
> ret_from_fork+0x1f/0x30
> -> #1 (&domain->iova_cookie->mutex){+.+.}-{3:3}:
> lock_acquire+0xd3/0x310
> __mutex_lock+0x97/0xf10
> iommu_setup_dma_ops+0xd7/0x440
> iommu_probe_device+0xa4/0x180
> iommu_bus_notifier+0x2d/0x40
> notifier_call_chain+0x31/0x90
> blocking_notifier_call_chain+0x3a/0x50
> device_add+0x3c1/0x900
> pci_device_add+0x255/0x580
> pci_scan_single_device+0xa6/0xd0
> pci_scan_slot+0x7a/0x1b0
> pci_scan_child_bus_extend+0x35/0x2a0
> vmd_probe+0x5cd/0x970
> pci_device_probe+0x95/0x110
> really_probe+0xd6/0x350
> __driver_probe_device+0x73/0x170
> driver_probe_device+0x1a/0x90
> __driver_attach+0xbc/0x190
> bus_for_each_dev+0x72/0xc0
> bus_add_driver+0x1bb/0x210
> driver_register+0x66/0xc0
> do_one_initcall+0x53/0x2f0
> kernel_init_freeable+0x18f/0x1e1
> kernel_init+0x11/0x120
> ret_from_fork+0x1f/0x30
> -> #0 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
> validate_chain+0xb3f/0x2000
> __lock_acquire+0x5a4/0xb70
> lock_acquire+0xd3/0x310
> down_read+0x39/0x140
> blocking_notifier_call_chain+0x20/0x50
> device_add+0x3c1/0x900
> platform_device_add+0x108/0x240
> coretemp_cpu_online+0xe1/0x15e [coretemp]
> cpuhp_invoke_callback+0x181/0x8a0
> cpuhp_thread_fun+0x188/0x1f0
> smpboot_thread_fn+0x1b5/0x260
> kthread+0xed/0x120
> ret_from_fork+0x1f/0x30
> other info that might help us debug thi
>Chain exists of &(&priv->bus_notifier)->rwsem --> cpu_hotplug_lock --> cpuhp_state-
> Possible unsafe locking scenari
> CPU0 CPU1
> ---- ----
> lock(cpuhp_state-up);
> lock(cpu_hotplug_lock);
> lock(cpuhp_state-up);
> lock(&(&priv->bus_notifier)->rwsem);
> *** DEADLOCK *
>2 locks held by cpuhp/0/15:
> #0: ffffffff82648f10 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x48/0x1f0
> #1: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x48/0x1f0
> stack backtrace:
>CPU: 0 PID: 15 Comm: cpuhp/0 Not tainted 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
>Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419 03/25/2022
>Call Trace:
> <TASK>
> dump_stack_lvl+0x56/0x7f
> check_noncircular+0x132/0x150
> validate_chain+0xb3f/0x2000
> __lock_acquire+0x5a4/0xb70
> lock_acquire+0xd3/0x310
> ? blocking_notifier_call_chain+0x20/0x50
> down_read+0x39/0x140
> ? blocking_notifier_call_chain+0x20/0x50
> blocking_notifier_call_chain+0x20/0x50
> device_add+0x3c1/0x900
> ? dev_set_name+0x4e/0x70
> platform_device_add+0x108/0x240
> coretemp_cpu_online+0xe1/0x15e [coretemp]
> ? create_core_data+0x550/0x550 [coretemp]
> cpuhp_invoke_callback+0x181/0x8a0
> cpuhp_thread_fun+0x188/0x1f0
> ? smpboot_thread_fn+0x1e/0x260
> smpboot_thread_fn+0x1b5/0x260
> ? sort_range+0x20/0x20
> kthread+0xed/0x120
> ? kthread_complete_and_exit+0x20/0x20
> ret_from_fork+0x1f/0x30
> </TASK>
>
>Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
>
>Signed-off-by: Karolina Drobnik <[email protected]>
>Cc: Lucas De Marchi <[email protected]>
>---
> drivers/iommu/dma-iommu.c | 17 ++++-------------
> 1 file changed, 4 insertions(+), 13 deletions(-)
>
>diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>index 17dd683b2fce..9616b473e4c7 100644
>--- a/drivers/iommu/dma-iommu.c
>+++ b/drivers/iommu/dma-iommu.c
>@@ -65,7 +65,6 @@ struct iommu_dma_cookie {
>
> /* Domain for flush queue callback; NULL if flush queue not in use */
> struct iommu_domain *fq_domain;
>- struct mutex mutex;
> };
>
> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
>@@ -312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
> if (!domain->iova_cookie)
> return -ENOMEM;
>
>- mutex_init(&domain->iova_cookie->mutex);
> return 0;
> }
>
>@@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
> }
>
> /* start_pfn is always nonzero for an already-initialised domain */
>- mutex_lock(&cookie->mutex);
> if (iovad->start_pfn) {
> if (1UL << order != iovad->granule ||
> base_pfn != iovad->start_pfn) {
> pr_warn("Incompatible range for DMA domain\n");
>- ret = -EFAULT;
>- goto done_unlock;
>+ return -EFAULT;
> }
>
>- ret = 0;
>- goto done_unlock;
>+ return 0;
> }
>
> init_iova_domain(iovad, 1UL << order, base_pfn);
> ret = iova_domain_init_rcaches(iovad);
> if (ret)
>- goto done_unlock;
>+ return ret;
>
> /* If the FQ fails we can simply fall back to strict mode */
> if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
> domain->type = IOMMU_DOMAIN_DMA;
>
>- ret = iova_reserve_iommu_regions(dev, domain);
>-
>-done_unlock:
>- mutex_unlock(&cookie->mutex);
>- return ret;
>+ return iova_reserve_iommu_regions(dev, domain);
> }
>
> /**
>--
>2.25.1
>
On 2022-09-14 16:01, Lucas De Marchi wrote:
> On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
>> This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
>>
>> This change introduces a regression on Alder Lake that completely
>> blocks testing. To enable CI and avoid possible circular locking
>> warning, revert the patch.
>
> We are already on rc5. Are iommu authors involved aware of this issue?
> We could do this in our "for CI only" branch, but it's equally important
> that this is fixed for 6.0
>
> Cc'ing them.
The lockdep report doesn't make much sense to me - the deadlock cycle
it's reporting doesn't even involve the mutex added by that commit, and
otherwise the lock ordering between the IOMMU bus notifier(s) and
cpu_hotplug_lock has existed for ages. Has lockdep somehow got multiple
different and unrelated bus notifiers mixed up, maybe?
FWIW nobody else has reported anything, and that mutex addresses a
real-world concurrency issue, so I'm not convinced a revert is
appropriate without at least a much clearer justification.
Robin.
> thanks
> Lucas De Marchi
>
>>
>> kernel log:
>>
>> ======================================================
>> WARNING: possible circular locking dependency detected
>> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
>> ------------------------------------------------------
>> cpuhp/0/15 is trying to acquire lock:
>> ffff8881013df278 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at:
>> blocking_notifier_call_chain+0x20/0x50
>> but task is already holding lock:
>> ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>> cpuhp_thread_fun+0x48/0x1f0
>> which lock already depends on the new loc
>> the existing dependency chain (in reverse order) is:
>> -> #3 (cpuhp_state-up){+.+.}-{0:0}:
>> lock_acquire+0xd3/0x310
>> cpuhp_thread_fun+0xa6/0x1f0
>> smpboot_thread_fn+0x1b5/0x260
>> kthread+0xed/0x120
>> ret_from_fork+0x1f/0x30
>> -> #2 (cpu_hotplug_lock){++++}-{0:0}:
>> lock_acquire+0xd3/0x310
>> __cpuhp_state_add_instance+0x43/0x1c0
>> iova_domain_init_rcaches+0x199/0x1c0
>> iommu_setup_dma_ops+0x130/0x440
>> bus_iommu_probe+0x26a/0x2d0
>> bus_set_iommu+0x82/0xd0
>> intel_iommu_init+0xe33/0x1039
>> pci_iommu_init+0x9/0x31
>> do_one_initcall+0x53/0x2f0
>> kernel_init_freeable+0x18f/0x1e1
>> kernel_init+0x11/0x120
>> ret_from_fork+0x1f/0x30
>> -> #1 (&domain->iova_cookie->mutex){+.+.}-{3:3}:
>> lock_acquire+0xd3/0x310
>> __mutex_lock+0x97/0xf10
>> iommu_setup_dma_ops+0xd7/0x440
>> iommu_probe_device+0xa4/0x180
>> iommu_bus_notifier+0x2d/0x40
>> notifier_call_chain+0x31/0x90
>> blocking_notifier_call_chain+0x3a/0x50
>> device_add+0x3c1/0x900
>> pci_device_add+0x255/0x580
>> pci_scan_single_device+0xa6/0xd0
>> pci_scan_slot+0x7a/0x1b0
>> pci_scan_child_bus_extend+0x35/0x2a0
>> vmd_probe+0x5cd/0x970
>> pci_device_probe+0x95/0x110
>> really_probe+0xd6/0x350
>> __driver_probe_device+0x73/0x170
>> driver_probe_device+0x1a/0x90
>> __driver_attach+0xbc/0x190
>> bus_for_each_dev+0x72/0xc0
>> bus_add_driver+0x1bb/0x210
>> driver_register+0x66/0xc0
>> do_one_initcall+0x53/0x2f0
>> kernel_init_freeable+0x18f/0x1e1
>> kernel_init+0x11/0x120
>> ret_from_fork+0x1f/0x30
>> -> #0 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
>> validate_chain+0xb3f/0x2000
>> __lock_acquire+0x5a4/0xb70
>> lock_acquire+0xd3/0x310
>> down_read+0x39/0x140
>> blocking_notifier_call_chain+0x20/0x50
>> device_add+0x3c1/0x900
>> platform_device_add+0x108/0x240
>> coretemp_cpu_online+0xe1/0x15e [coretemp]
>> cpuhp_invoke_callback+0x181/0x8a0
>> cpuhp_thread_fun+0x188/0x1f0
>> smpboot_thread_fn+0x1b5/0x260
>> kthread+0xed/0x120
>> ret_from_fork+0x1f/0x30
>> other info that might help us debug thi
>> Chain exists of &(&priv->bus_notifier)->rwsem -->
>> cpu_hotplug_lock --> cpuhp_state-
>> Possible unsafe locking scenari
>> CPU0 CPU1
>> ---- ----
>> lock(cpuhp_state-up);
>> lock(cpu_hotplug_lock);
>> lock(cpuhp_state-up);
>> lock(&(&priv->bus_notifier)->rwsem);
>> *** DEADLOCK *
>> 2 locks held by cpuhp/0/15:
>> #0: ffffffff82648f10 (cpu_hotplug_lock){++++}-{0:0}, at:
>> cpuhp_thread_fun+0x48/0x1f0
>> #1: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>> cpuhp_thread_fun+0x48/0x1f0
>> stack backtrace:
>> CPU: 0 PID: 15 Comm: cpuhp/0 Not tainted
>> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
>> Hardware name: Intel Corporation Alder Lake Client
>> Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419
>> 03/25/2022
>> Call Trace:
>> <TASK>
>> dump_stack_lvl+0x56/0x7f
>> check_noncircular+0x132/0x150
>> validate_chain+0xb3f/0x2000
>> __lock_acquire+0x5a4/0xb70
>> lock_acquire+0xd3/0x310
>> ? blocking_notifier_call_chain+0x20/0x50
>> down_read+0x39/0x140
>> ? blocking_notifier_call_chain+0x20/0x50
>> blocking_notifier_call_chain+0x20/0x50
>> device_add+0x3c1/0x900
>> ? dev_set_name+0x4e/0x70
>> platform_device_add+0x108/0x240
>> coretemp_cpu_online+0xe1/0x15e [coretemp]
>> ? create_core_data+0x550/0x550 [coretemp]
>> cpuhp_invoke_callback+0x181/0x8a0
>> cpuhp_thread_fun+0x188/0x1f0
>> ? smpboot_thread_fn+0x1e/0x260
>> smpboot_thread_fn+0x1b5/0x260
>> ? sort_range+0x20/0x20
>> kthread+0xed/0x120
>> ? kthread_complete_and_exit+0x20/0x20
>> ret_from_fork+0x1f/0x30
>> </TASK>
>>
>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
>>
>> Signed-off-by: Karolina Drobnik <[email protected]>
>> Cc: Lucas De Marchi <[email protected]>
>> ---
>> drivers/iommu/dma-iommu.c | 17 ++++-------------
>> 1 file changed, 4 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>> index 17dd683b2fce..9616b473e4c7 100644
>> --- a/drivers/iommu/dma-iommu.c
>> +++ b/drivers/iommu/dma-iommu.c
>> @@ -65,7 +65,6 @@ struct iommu_dma_cookie {
>>
>> /* Domain for flush queue callback; NULL if flush queue not in use */
>> struct iommu_domain *fq_domain;
>> - struct mutex mutex;
>> };
>>
>> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
>> @@ -312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
>> if (!domain->iova_cookie)
>> return -ENOMEM;
>>
>> - mutex_init(&domain->iova_cookie->mutex);
>> return 0;
>> }
>>
>> @@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct
>> iommu_domain *domain, dma_addr_t base,
>> }
>>
>> /* start_pfn is always nonzero for an already-initialised domain */
>> - mutex_lock(&cookie->mutex);
>> if (iovad->start_pfn) {
>> if (1UL << order != iovad->granule ||
>> base_pfn != iovad->start_pfn) {
>> pr_warn("Incompatible range for DMA domain\n");
>> - ret = -EFAULT;
>> - goto done_unlock;
>> + return -EFAULT;
>> }
>>
>> - ret = 0;
>> - goto done_unlock;
>> + return 0;
>> }
>>
>> init_iova_domain(iovad, 1UL << order, base_pfn);
>> ret = iova_domain_init_rcaches(iovad);
>> if (ret)
>> - goto done_unlock;
>> + return ret;
>>
>> /* If the FQ fails we can simply fall back to strict mode */
>> if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
>> domain->type = IOMMU_DOMAIN_DMA;
>>
>> - ret = iova_reserve_iommu_regions(dev, domain);
>> -
>> -done_unlock:
>> - mutex_unlock(&cookie->mutex);
>> - return ret;
>> + return iova_reserve_iommu_regions(dev, domain);
>> }
>>
>> /**
>> --
>> 2.25.1
>>
On 14.09.2022 17:01, Lucas De Marchi wrote:
> On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
>> This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
>>
>> This change introduces a regression on Alder Lake that completely
>> blocks testing. To enable CI and avoid possible circular locking
>> warning, revert the patch.
>
> We are already on rc5. Are iommu authors involved aware of this issue?
> We could do this in our "for CI only" branch, but it's equally important
> that this is fixed for 6.0
I planned to reach out to them after merging this revert on "CI only"
branch (hence the topic tag) with more justification. And yes, I'm fully
aware we're quite late in the cycle, so that's also why I went with this
patch first.
Many thanks,
Karolina
> Cc'ing them.
>
> thanks
> Lucas De Marchi
>
>>
>> kernel log:
>>
>> ======================================================
>> WARNING: possible circular locking dependency detected
>> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
>> ------------------------------------------------------
>> cpuhp/0/15 is trying to acquire lock:
>> ffff8881013df278 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at:
>> blocking_notifier_call_chain+0x20/0x50
>> but task is already holding lock:
>> ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>> cpuhp_thread_fun+0x48/0x1f0
>> which lock already depends on the new loc
>> the existing dependency chain (in reverse order) is:
>> -> #3 (cpuhp_state-up){+.+.}-{0:0}:
>> lock_acquire+0xd3/0x310
>> cpuhp_thread_fun+0xa6/0x1f0
>> smpboot_thread_fn+0x1b5/0x260
>> kthread+0xed/0x120
>> ret_from_fork+0x1f/0x30
>> -> #2 (cpu_hotplug_lock){++++}-{0:0}:
>> lock_acquire+0xd3/0x310
>> __cpuhp_state_add_instance+0x43/0x1c0
>> iova_domain_init_rcaches+0x199/0x1c0
>> iommu_setup_dma_ops+0x130/0x440
>> bus_iommu_probe+0x26a/0x2d0
>> bus_set_iommu+0x82/0xd0
>> intel_iommu_init+0xe33/0x1039
>> pci_iommu_init+0x9/0x31
>> do_one_initcall+0x53/0x2f0
>> kernel_init_freeable+0x18f/0x1e1
>> kernel_init+0x11/0x120
>> ret_from_fork+0x1f/0x30
>> -> #1 (&domain->iova_cookie->mutex){+.+.}-{3:3}:
>> lock_acquire+0xd3/0x310
>> __mutex_lock+0x97/0xf10
>> iommu_setup_dma_ops+0xd7/0x440
>> iommu_probe_device+0xa4/0x180
>> iommu_bus_notifier+0x2d/0x40
>> notifier_call_chain+0x31/0x90
>> blocking_notifier_call_chain+0x3a/0x50
>> device_add+0x3c1/0x900
>> pci_device_add+0x255/0x580
>> pci_scan_single_device+0xa6/0xd0
>> pci_scan_slot+0x7a/0x1b0
>> pci_scan_child_bus_extend+0x35/0x2a0
>> vmd_probe+0x5cd/0x970
>> pci_device_probe+0x95/0x110
>> really_probe+0xd6/0x350
>> __driver_probe_device+0x73/0x170
>> driver_probe_device+0x1a/0x90
>> __driver_attach+0xbc/0x190
>> bus_for_each_dev+0x72/0xc0
>> bus_add_driver+0x1bb/0x210
>> driver_register+0x66/0xc0
>> do_one_initcall+0x53/0x2f0
>> kernel_init_freeable+0x18f/0x1e1
>> kernel_init+0x11/0x120
>> ret_from_fork+0x1f/0x30
>> -> #0 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
>> validate_chain+0xb3f/0x2000
>> __lock_acquire+0x5a4/0xb70
>> lock_acquire+0xd3/0x310
>> down_read+0x39/0x140
>> blocking_notifier_call_chain+0x20/0x50
>> device_add+0x3c1/0x900
>> platform_device_add+0x108/0x240
>> coretemp_cpu_online+0xe1/0x15e [coretemp]
>> cpuhp_invoke_callback+0x181/0x8a0
>> cpuhp_thread_fun+0x188/0x1f0
>> smpboot_thread_fn+0x1b5/0x260
>> kthread+0xed/0x120
>> ret_from_fork+0x1f/0x30
>> other info that might help us debug thi
>> Chain exists of &(&priv->bus_notifier)->rwsem -->
>> cpu_hotplug_lock --> cpuhp_state-
>> Possible unsafe locking scenari
>> CPU0 CPU1
>> ---- ----
>> lock(cpuhp_state-up);
>> lock(cpu_hotplug_lock);
>> lock(cpuhp_state-up);
>> lock(&(&priv->bus_notifier)->rwsem);
>> *** DEADLOCK *
>> 2 locks held by cpuhp/0/15:
>> #0: ffffffff82648f10 (cpu_hotplug_lock){++++}-{0:0}, at:
>> cpuhp_thread_fun+0x48/0x1f0
>> #1: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>> cpuhp_thread_fun+0x48/0x1f0
>> stack backtrace:
>> CPU: 0 PID: 15 Comm: cpuhp/0 Not tainted
>> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
>> Hardware name: Intel Corporation Alder Lake Client
>> Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419
>> 03/25/2022
>> Call Trace:
>> <TASK>
>> dump_stack_lvl+0x56/0x7f
>> check_noncircular+0x132/0x150
>> validate_chain+0xb3f/0x2000
>> __lock_acquire+0x5a4/0xb70
>> lock_acquire+0xd3/0x310
>> ? blocking_notifier_call_chain+0x20/0x50
>> down_read+0x39/0x140
>> ? blocking_notifier_call_chain+0x20/0x50
>> blocking_notifier_call_chain+0x20/0x50
>> device_add+0x3c1/0x900
>> ? dev_set_name+0x4e/0x70
>> platform_device_add+0x108/0x240
>> coretemp_cpu_online+0xe1/0x15e [coretemp]
>> ? create_core_data+0x550/0x550 [coretemp]
>> cpuhp_invoke_callback+0x181/0x8a0
>> cpuhp_thread_fun+0x188/0x1f0
>> ? smpboot_thread_fn+0x1e/0x260
>> smpboot_thread_fn+0x1b5/0x260
>> ? sort_range+0x20/0x20
>> kthread+0xed/0x120
>> ? kthread_complete_and_exit+0x20/0x20
>> ret_from_fork+0x1f/0x30
>> </TASK>
>>
>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
>>
>> Signed-off-by: Karolina Drobnik <[email protected]>
>> Cc: Lucas De Marchi <[email protected]>
>> ---
>> drivers/iommu/dma-iommu.c | 17 ++++-------------
>> 1 file changed, 4 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>> index 17dd683b2fce..9616b473e4c7 100644
>> --- a/drivers/iommu/dma-iommu.c
>> +++ b/drivers/iommu/dma-iommu.c
>> @@ -65,7 +65,6 @@ struct iommu_dma_cookie {
>>
>> /* Domain for flush queue callback; NULL if flush queue not in use */
>> struct iommu_domain *fq_domain;
>> - struct mutex mutex;
>> };
>>
>> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
>> @@ -312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
>> if (!domain->iova_cookie)
>> return -ENOMEM;
>>
>> - mutex_init(&domain->iova_cookie->mutex);
>> return 0;
>> }
>>
>> @@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct
>> iommu_domain *domain, dma_addr_t base,
>> }
>>
>> /* start_pfn is always nonzero for an already-initialised domain */
>> - mutex_lock(&cookie->mutex);
>> if (iovad->start_pfn) {
>> if (1UL << order != iovad->granule ||
>> base_pfn != iovad->start_pfn) {
>> pr_warn("Incompatible range for DMA domain\n");
>> - ret = -EFAULT;
>> - goto done_unlock;
>> + return -EFAULT;
>> }
>>
>> - ret = 0;
>> - goto done_unlock;
>> + return 0;
>> }
>>
>> init_iova_domain(iovad, 1UL << order, base_pfn);
>> ret = iova_domain_init_rcaches(iovad);
>> if (ret)
>> - goto done_unlock;
>> + return ret;
>>
>> /* If the FQ fails we can simply fall back to strict mode */
>> if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
>> domain->type = IOMMU_DOMAIN_DMA;
>>
>> - ret = iova_reserve_iommu_regions(dev, domain);
>> -
>> -done_unlock:
>> - mutex_unlock(&cookie->mutex);
>> - return ret;
>> + return iova_reserve_iommu_regions(dev, domain);
>> }
>>
>> /**
>> --
>> 2.25.1
>>
On 14.09.2022 17:54, Robin Murphy wrote:
> On 2022-09-14 16:01, Lucas De Marchi wrote:
>> On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
>>> This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
>>>
>>> This change introduces a regression on Alder Lake that
>>> completely blocks testing. To enable CI and avoid possible
>>> circular locking warning, revert the patch.
>>
>> We are already on rc5. Are iommu authors involved aware of this
>> issue? We could do this in our "for CI only" branch, but it's
>> equally important that this is fixed for 6.0
>>
>> Cc'ing them.
>
> The lockdep report doesn't make much sense to me - the deadlock cycle
> it's reporting doesn't even involve the mutex added by that commit,
> and otherwise the lock ordering between the IOMMU bus notifier(s) and
> cpu_hotplug_lock has existed for ages. Has lockdep somehow got
> multiple different and unrelated bus notifiers mixed up, maybe?
>
> FWIW nobody else has reported anything, and that mutex addresses a
> real-world concurrency issue, so I'm not convinced a revert is
> appropriate without at least a much clearer justification.
I'll share more background on this regression. We've noticed that no
tests were run for Alder Lake platforms. This may happens when, for
example, there is a kernel taint or lockdep warning.
Links:
https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlm-1.html
https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlp-6.html
The CI logs (which can be found for example here[1], boot0 file)
revealed a lockdep warning. One of the recent changes in the area was
commit ac9a5d522bb8 ("iommu/dma: Fix race condition during iova_domain
initialization"), and I sent a revert patch to test it on CI[2]. This
proved to be effective, as the tests started running on Alder Lake
platform:
https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_108474v1/index.html?hosts=adlp
To be clear, that revert is just a way of unblocking CI testing, the
problem requires a specific fix.
Lucas, would it be possible to merge this revert to the topic branch to
unblock Alder Lake until this issue is fixed? I'm afraid that some
regressions could slip through the cracks if we don't do it soon enough.
Thanks,
Karolina
----
[1] -
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12145/bat-adlm-1/igt@[email protected]
[2] - https://patchwork.freedesktop.org/series/108474/
> Robin.
>
>> thanks Lucas De Marchi
>>
>>>
>>> kernel log:
>>>
>>> ====================================================== WARNING:
>>> possible circular locking dependency detected
>>> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
>>> ------------------------------------------------------ cpuhp/0/15
>>> is trying to acquire lock: ffff8881013df278
>>> (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at:
>>> blocking_notifier_call_chain+0x20/0x50 but task is already
>>> holding lock: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>>> cpuhp_thread_fun+0x48/0x1f0 which lock already depends on the
>>> new loc the existing dependency chain (in reverse order) is: ->
>>> #3 (cpuhp_state-up){+.+.}-{0:0}: lock_acquire+0xd3/0x310
>>> cpuhp_thread_fun+0xa6/0x1f0 smpboot_thread_fn+0x1b5/0x260
>>> kthread+0xed/0x120 ret_from_fork+0x1f/0x30 -> #2
>>> (cpu_hotplug_lock){++++}-{0:0}: lock_acquire+0xd3/0x310
>>> __cpuhp_state_add_instance+0x43/0x1c0
>>> iova_domain_init_rcaches+0x199/0x1c0
>>> iommu_setup_dma_ops+0x130/0x440 bus_iommu_probe+0x26a/0x2d0
>>> bus_set_iommu+0x82/0xd0 intel_iommu_init+0xe33/0x1039
>>> pci_iommu_init+0x9/0x31 do_one_initcall+0x53/0x2f0
>>> kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120
>>> ret_from_fork+0x1f/0x30 -> #1
>>> (&domain->iova_cookie->mutex){+.+.}-{3:3}:
>>> lock_acquire+0xd3/0x310 __mutex_lock+0x97/0xf10
>>> iommu_setup_dma_ops+0xd7/0x440 iommu_probe_device+0xa4/0x180
>>> iommu_bus_notifier+0x2d/0x40 notifier_call_chain+0x31/0x90
>>> blocking_notifier_call_chain+0x3a/0x50 device_add+0x3c1/0x900
>>> pci_device_add+0x255/0x580 pci_scan_single_device+0xa6/0xd0
>>> pci_scan_slot+0x7a/0x1b0 pci_scan_child_bus_extend+0x35/0x2a0
>>> vmd_probe+0x5cd/0x970 pci_device_probe+0x95/0x110
>>> really_probe+0xd6/0x350 __driver_probe_device+0x73/0x170
>>> driver_probe_device+0x1a/0x90 __driver_attach+0xbc/0x190
>>> bus_for_each_dev+0x72/0xc0 bus_add_driver+0x1bb/0x210
>>> driver_register+0x66/0xc0 do_one_initcall+0x53/0x2f0
>>> kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120
>>> ret_from_fork+0x1f/0x30 -> #0
>>> (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
>>> validate_chain+0xb3f/0x2000 __lock_acquire+0x5a4/0xb70
>>> lock_acquire+0xd3/0x310 down_read+0x39/0x140
>>> blocking_notifier_call_chain+0x20/0x50 device_add+0x3c1/0x900
>>> platform_device_add+0x108/0x240 coretemp_cpu_online+0xe1/0x15e
>>> [coretemp] cpuhp_invoke_callback+0x181/0x8a0
>>> cpuhp_thread_fun+0x188/0x1f0 smpboot_thread_fn+0x1b5/0x260
>>> kthread+0xed/0x120 ret_from_fork+0x1f/0x30 other info that might
>>> help us debug thi Chain exists of &(&priv->bus_notifier)->rwsem
>>> --> cpu_hotplug_lock --> cpuhp_state- Possible unsafe locking
>>> scenari CPU0 CPU1 ---- ----
>>> lock(cpuhp_state-up); lock(cpu_hotplug_lock);
>>> lock(cpuhp_state-up); lock(&(&priv->bus_notifier)->rwsem); ***
>>> DEADLOCK * 2 locks held by cpuhp/0/15: #0: ffffffff82648f10
>>> (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x48/0x1f0
>>> #1: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>>> cpuhp_thread_fun+0x48/0x1f0 stack backtrace: CPU: 0 PID: 15 Comm:
>>> cpuhp/0 Not tainted 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
>>> Hardware name: Intel Corporation Alder Lake Client
>>> Platform/AlderLake-P DDR4 RVP, BIOS
>>> ADLPFWI1.R00.3135.A00.2203251419 03/25/2022 Call Trace: <TASK>
>>> dump_stack_lvl+0x56/0x7f check_noncircular+0x132/0x150
>>> validate_chain+0xb3f/0x2000 __lock_acquire+0x5a4/0xb70
>>> lock_acquire+0xd3/0x310 ? blocking_notifier_call_chain+0x20/0x50
>>> down_read+0x39/0x140 ? blocking_notifier_call_chain+0x20/0x50
>>> blocking_notifier_call_chain+0x20/0x50 device_add+0x3c1/0x900 ?
>>> dev_set_name+0x4e/0x70 platform_device_add+0x108/0x240
>>> coretemp_cpu_online+0xe1/0x15e [coretemp] ?
>>> create_core_data+0x550/0x550 [coretemp]
>>> cpuhp_invoke_callback+0x181/0x8a0 cpuhp_thread_fun+0x188/0x1f0 ?
>>> smpboot_thread_fn+0x1e/0x260 smpboot_thread_fn+0x1b5/0x260 ?
>>> sort_range+0x20/0x20 kthread+0xed/0x120 ?
>>> kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30
>>> </TASK>
>>>
>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
>>>
>>> Signed-off-by: Karolina Drobnik <[email protected]> Cc:
>>> Lucas De Marchi <[email protected]> ---
>>> drivers/iommu/dma-iommu.c | 17 ++++------------- 1 file changed,
>>> 4 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/drivers/iommu/dma-iommu.c
>>> b/drivers/iommu/dma-iommu.c index 17dd683b2fce..9616b473e4c7
>>> 100644 --- a/drivers/iommu/dma-iommu.c +++
>>> b/drivers/iommu/dma-iommu.c @@ -65,7 +65,6 @@ struct
>>> iommu_dma_cookie {
>>>
>>> /* Domain for flush queue callback; NULL if flush queue not in
>>> use */ struct iommu_domain *fq_domain; - struct mutex
>>> mutex; };
>>>
>>> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled); @@
>>> -312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain
>>> *domain) if (!domain->iova_cookie) return -ENOMEM;
>>>
>>> - mutex_init(&domain->iova_cookie->mutex); return 0; }
>>>
>>> @@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct
>>> iommu_domain *domain, dma_addr_t base, }
>>>
>>> /* start_pfn is always nonzero for an already-initialised domain
>>> */ - mutex_lock(&cookie->mutex); if (iovad->start_pfn) { if
>>> (1UL << order != iovad->granule || base_pfn != iovad->start_pfn)
>>> { pr_warn("Incompatible range for DMA domain\n"); - ret =
>>> -EFAULT; - goto done_unlock; + return
>>> -EFAULT; }
>>>
>>> - ret = 0; - goto done_unlock; + return 0;
>>> }
>>>
>>> init_iova_domain(iovad, 1UL << order, base_pfn); ret =
>>> iova_domain_init_rcaches(iovad); if (ret) - goto
>>> done_unlock; + return ret;
>>>
>>> /* If the FQ fails we can simply fall back to strict mode */ if
>>> (domain->type == IOMMU_DOMAIN_DMA_FQ &&
>>> iommu_dma_init_fq(domain)) domain->type = IOMMU_DOMAIN_DMA;
>>>
>>> - ret = iova_reserve_iommu_regions(dev, domain); -
>>> -done_unlock: - mutex_unlock(&cookie->mutex); - return
>>> ret; + return iova_reserve_iommu_regions(dev, domain); }
>>>
>>> /** -- 2.25.1
>>>
On Fri, Sep 16, 2022 at 02:24:00PM +0200, Karolina Drobnik wrote:
>On 14.09.2022 17:54, Robin Murphy wrote:
>>On 2022-09-14 16:01, Lucas De Marchi wrote:
>>>On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
>>>>This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
>>>>
>>>>This change introduces a regression on Alder Lake that
>>>>completely blocks testing. To enable CI and avoid possible
>>>>circular locking warning, revert the patch.
>>>
>>>We are already on rc5. Are iommu authors involved aware of this
>>>issue? We could do this in our "for CI only" branch, but it's
>>>equally important that this is fixed for 6.0
>>>
>>>Cc'ing them.
>>
>>The lockdep report doesn't make much sense to me - the deadlock cycle
>>it's reporting doesn't even involve the mutex added by that commit,
>>and otherwise the lock ordering between the IOMMU bus notifier(s) and
>>cpu_hotplug_lock has existed for ages. Has lockdep somehow got
>>multiple different and unrelated bus notifiers mixed up, maybe?
>>
>>FWIW nobody else has reported anything, and that mutex addresses a
>>real-world concurrency issue, so I'm not convinced a revert is
>>appropriate without at least a much clearer justification.
>
>I'll share more background on this regression. We've noticed that no
>tests were run for Alder Lake platforms. This may happens when, for
>example, there is a kernel taint or lockdep warning.
>
>Links:
>https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlm-1.html
>https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlp-6.html
>
>The CI logs (which can be found for example here[1], boot0 file)
>revealed a lockdep warning. One of the recent changes in the area was
>commit ac9a5d522bb8 ("iommu/dma: Fix race condition during iova_domain
>initialization"), and I sent a revert patch to test it on CI[2]. This
>proved to be effective, as the tests started running on Alder Lake
>platform:
>https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_108474v1/index.html?hosts=adlp
>
>To be clear, that revert is just a way of unblocking CI testing, the
>problem requires a specific fix.
>
>Lucas, would it be possible to merge this revert to the topic branch to
>unblock Alder Lake until this issue is fixed? I'm afraid that some
>regressions could slip through the cracks if we don't do it soon enough.
Yeah. Let's have CI running with the revertt so we can see if on next runs
it will really show it was a regression or if it's something else. I
think it will help us understand why it's failing.
Lucas De Marchi
>
>Thanks,
>Karolina
>
>----
>[1] -
>https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12145/bat-adlm-1/igt@[email protected]
>[2] - https://patchwork.freedesktop.org/series/108474/
>
>>Robin.
>>
>>>thanks Lucas De Marchi
>>>
>>>>
>>>>kernel log:
>>>>
>>>>====================================================== WARNING:
>>>>possible circular locking dependency detected
>>>>6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
>>>>------------------------------------------------------
>>>>cpuhp/0/15
>>>>is trying to acquire lock: ffff8881013df278
>>>>(&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at:
>>>>blocking_notifier_call_chain+0x20/0x50 but task is already
>>>>holding lock: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>>>> cpuhp_thread_fun+0x48/0x1f0 which lock already depends on the
>>>>new loc the existing dependency chain (in reverse order) is: ->
>>>>#3 (cpuhp_state-up){+.+.}-{0:0}: lock_acquire+0xd3/0x310
>>>>cpuhp_thread_fun+0xa6/0x1f0 smpboot_thread_fn+0x1b5/0x260
>>>>kthread+0xed/0x120 ret_from_fork+0x1f/0x30 -> #2
>>>>(cpu_hotplug_lock){++++}-{0:0}: lock_acquire+0xd3/0x310
>>>>__cpuhp_state_add_instance+0x43/0x1c0
>>>>iova_domain_init_rcaches+0x199/0x1c0
>>>>iommu_setup_dma_ops+0x130/0x440 bus_iommu_probe+0x26a/0x2d0
>>>>bus_set_iommu+0x82/0xd0 intel_iommu_init+0xe33/0x1039
>>>>pci_iommu_init+0x9/0x31 do_one_initcall+0x53/0x2f0
>>>>kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120
>>>>ret_from_fork+0x1f/0x30 -> #1
>>>>(&domain->iova_cookie->mutex){+.+.}-{3:3}:
>>>>lock_acquire+0xd3/0x310 __mutex_lock+0x97/0xf10
>>>>iommu_setup_dma_ops+0xd7/0x440 iommu_probe_device+0xa4/0x180
>>>>iommu_bus_notifier+0x2d/0x40 notifier_call_chain+0x31/0x90
>>>>blocking_notifier_call_chain+0x3a/0x50 device_add+0x3c1/0x900
>>>>pci_device_add+0x255/0x580 pci_scan_single_device+0xa6/0xd0
>>>>pci_scan_slot+0x7a/0x1b0 pci_scan_child_bus_extend+0x35/0x2a0
>>>>vmd_probe+0x5cd/0x970 pci_device_probe+0x95/0x110
>>>>really_probe+0xd6/0x350 __driver_probe_device+0x73/0x170
>>>>driver_probe_device+0x1a/0x90 __driver_attach+0xbc/0x190
>>>>bus_for_each_dev+0x72/0xc0 bus_add_driver+0x1bb/0x210
>>>>driver_register+0x66/0xc0 do_one_initcall+0x53/0x2f0
>>>>kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120
>>>>ret_from_fork+0x1f/0x30 -> #0
>>>>(&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
>>>>validate_chain+0xb3f/0x2000 __lock_acquire+0x5a4/0xb70
>>>>lock_acquire+0xd3/0x310 down_read+0x39/0x140
>>>>blocking_notifier_call_chain+0x20/0x50 device_add+0x3c1/0x900
>>>>platform_device_add+0x108/0x240 coretemp_cpu_online+0xe1/0x15e
>>>>[coretemp] cpuhp_invoke_callback+0x181/0x8a0
>>>>cpuhp_thread_fun+0x188/0x1f0 smpboot_thread_fn+0x1b5/0x260
>>>>kthread+0xed/0x120 ret_from_fork+0x1f/0x30 other info that might
>>>> help us debug thi Chain exists of &(&priv->bus_notifier)->rwsem
>>>>--> cpu_hotplug_lock --> cpuhp_state- Possible unsafe locking
>>>>scenari CPU0 CPU1 ---- ----
>>>>lock(cpuhp_state-up); lock(cpu_hotplug_lock);
>>>>lock(cpuhp_state-up); lock(&(&priv->bus_notifier)->rwsem); ***
>>>>DEADLOCK * 2 locks held by cpuhp/0/15: #0: ffffffff82648f10
>>>>(cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x48/0x1f0
>>>>#1: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>>>>cpuhp_thread_fun+0x48/0x1f0 stack backtrace: CPU: 0 PID: 15
>>>>Comm:
>>>>cpuhp/0 Not tainted 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
>>>>Hardware name: Intel Corporation Alder Lake Client
>>>>Platform/AlderLake-P DDR4 RVP, BIOS
>>>>ADLPFWI1.R00.3135.A00.2203251419 03/25/2022 Call Trace: <TASK>
>>>>dump_stack_lvl+0x56/0x7f check_noncircular+0x132/0x150
>>>>validate_chain+0xb3f/0x2000 __lock_acquire+0x5a4/0xb70
>>>>lock_acquire+0xd3/0x310 ? blocking_notifier_call_chain+0x20/0x50
>>>>down_read+0x39/0x140 ? blocking_notifier_call_chain+0x20/0x50
>>>>blocking_notifier_call_chain+0x20/0x50 device_add+0x3c1/0x900 ?
>>>>dev_set_name+0x4e/0x70 platform_device_add+0x108/0x240
>>>>coretemp_cpu_online+0xe1/0x15e [coretemp] ?
>>>>create_core_data+0x550/0x550 [coretemp]
>>>>cpuhp_invoke_callback+0x181/0x8a0 cpuhp_thread_fun+0x188/0x1f0 ?
>>>> smpboot_thread_fn+0x1e/0x260 smpboot_thread_fn+0x1b5/0x260 ?
>>>>sort_range+0x20/0x20 kthread+0xed/0x120 ?
>>>>kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30
>>>></TASK>
>>>>
>>>>Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
>>>>
>>>>Signed-off-by: Karolina Drobnik <[email protected]> Cc:
>>>> Lucas De Marchi <[email protected]> ---
>>>>drivers/iommu/dma-iommu.c | 17 ++++------------- 1 file changed,
>>>> 4 insertions(+), 13 deletions(-)
>>>>
>>>>diff --git a/drivers/iommu/dma-iommu.c
>>>>b/drivers/iommu/dma-iommu.c index 17dd683b2fce..9616b473e4c7
>>>>100644 --- a/drivers/iommu/dma-iommu.c +++
>>>>b/drivers/iommu/dma-iommu.c @@ -65,7 +65,6 @@ struct
>>>>iommu_dma_cookie {
>>>>
>>>>/* Domain for flush queue callback; NULL if flush queue not in
>>>>use */ struct iommu_domain *fq_domain; - struct mutex
>>>>mutex; };
>>>>
>>>>static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled); @@
>>>>-312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain
>>>>*domain) if (!domain->iova_cookie) return -ENOMEM;
>>>>
>>>>- mutex_init(&domain->iova_cookie->mutex); return 0; }
>>>>
>>>>@@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct
>>>>iommu_domain *domain, dma_addr_t base, }
>>>>
>>>>/* start_pfn is always nonzero for an already-initialised domain
>>>> */ - mutex_lock(&cookie->mutex); if (iovad->start_pfn) { if
>>>>(1UL << order != iovad->granule || base_pfn != iovad->start_pfn)
>>>> { pr_warn("Incompatible range for DMA domain\n"); - ret =
>>>>-EFAULT; - goto done_unlock; + return
>>>>-EFAULT; }
>>>>
>>>>- ret = 0; - goto done_unlock; + return 0;
>>>>}
>>>>
>>>>init_iova_domain(iovad, 1UL << order, base_pfn); ret =
>>>>iova_domain_init_rcaches(iovad); if (ret) - goto
>>>>done_unlock; + return ret;
>>>>
>>>>/* If the FQ fails we can simply fall back to strict mode */ if
>>>>(domain->type == IOMMU_DOMAIN_DMA_FQ &&
>>>>iommu_dma_init_fq(domain)) domain->type = IOMMU_DOMAIN_DMA;
>>>>
>>>>- ret = iova_reserve_iommu_regions(dev, domain); -
>>>>-done_unlock: - mutex_unlock(&cookie->mutex); - return
>>>>ret; + return iova_reserve_iommu_regions(dev, domain); }
>>>>
>>>>/** -- 2.25.1
>>>>
On 16.09.2022 22:32, Lucas De Marchi wrote:
> On Fri, Sep 16, 2022 at 02:24:00PM +0200, Karolina Drobnik wrote:
>> On 14.09.2022 17:54, Robin Murphy wrote:
>>> On 2022-09-14 16:01, Lucas De Marchi wrote:
>>>> On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
>>>>> This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
>>>>>
>>>>> This change introduces a regression on Alder Lake that
>>>>> completely blocks testing. To enable CI and avoid possible
>>>>> circular locking warning, revert the patch.
>>>>
>>>> We are already on rc5. Are iommu authors involved aware of this
>>>> issue? We could do this in our "for CI only" branch, but it's
>>>> equally important that this is fixed for 6.0
>>>>
>>>> Cc'ing them.
>>>
>>> The lockdep report doesn't make much sense to me - the deadlock cycle
>>> it's reporting doesn't even involve the mutex added by that commit,
>>> and otherwise the lock ordering between the IOMMU bus notifier(s) and
>>> cpu_hotplug_lock has existed for ages. Has lockdep somehow got
>>> multiple different and unrelated bus notifiers mixed up, maybe?
>>>
>>> FWIW nobody else has reported anything, and that mutex addresses a
>>> real-world concurrency issue, so I'm not convinced a revert is
>>> appropriate without at least a much clearer justification.
>>
>> I'll share more background on this regression. We've noticed that no
>> tests were run for Alder Lake platforms. This may happens when, for
>> example, there is a kernel taint or lockdep warning.
>>
>> Links:
>> https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlm-1.html
>> https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlp-6.html
>>
>> The CI logs (which can be found for example here[1], boot0 file)
>> revealed a lockdep warning. One of the recent changes in the area was
>> commit ac9a5d522bb8 ("iommu/dma: Fix race condition during iova_domain
>> initialization"), and I sent a revert patch to test it on CI[2]. This
>> proved to be effective, as the tests started running on Alder Lake
>> platform:
>> https://intel-gfx-ci.01.org/tree/drm-tip/Trybot_108474v1/index.html?hosts=adlp
>>
>>
>> To be clear, that revert is just a way of unblocking CI testing, the
>> problem requires a specific fix.
>>
>> Lucas, would it be possible to merge this revert to the topic branch to
>> unblock Alder Lake until this issue is fixed? I'm afraid that some
>> regressions could slip through the cracks if we don't do it soon enough.
>
> Yeah. Let's have CI running with the revertt so we can see if on next runs
> it will really show it was a regression or if it's something else. I
> think it will help us understand why it's failing.
Thanks for the merge. It looks like all adls are doing better now
(revert went in CI_DRM_12147):
https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlp-6.html
https://intel-gfx-ci.01.org/tree/drm-tip/bat-adln-1.html
https://intel-gfx-ci.01.org/tree/drm-tip/bat-adlm-1.html (CI_DRM_12149
seems to show a different problem)
All the best,
Karolina
>
> Lucas De Marchi
>
>
>>
>> Thanks,
>> Karolina
>>
>> ----
>> [1] -
>> https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_12145/bat-adlm-1/igt@[email protected]
>>
>> [2] - https://patchwork.freedesktop.org/series/108474/
>>
>>> Robin.
>>>
>>>> thanks Lucas De Marchi
>>>>
>>>>>
>>>>> kernel log:
>>>>>
>>>>> ====================================================== WARNING:
>>>>> possible circular locking dependency detected
>>>>> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
>>>>> ------------------------------------------------------ cpuhp/0/15
>>>>> is trying to acquire lock: ffff8881013df278
>>>>> (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at:
>>>>> blocking_notifier_call_chain+0x20/0x50 but task is already holding
>>>>> lock: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
>>>>> cpuhp_thread_fun+0x48/0x1f0 which lock already depends on the
>>>>> new loc the existing dependency chain (in reverse order) is: ->
>>>>> #3 (cpuhp_state-up){+.+.}-{0:0}: lock_acquire+0xd3/0x310
>>>>> cpuhp_thread_fun+0xa6/0x1f0 smpboot_thread_fn+0x1b5/0x260
>>>>> kthread+0xed/0x120 ret_from_fork+0x1f/0x30 -> #2
>>>>> (cpu_hotplug_lock){++++}-{0:0}: lock_acquire+0xd3/0x310
>>>>> __cpuhp_state_add_instance+0x43/0x1c0
>>>>> iova_domain_init_rcaches+0x199/0x1c0
>>>>> iommu_setup_dma_ops+0x130/0x440 bus_iommu_probe+0x26a/0x2d0
>>>>> bus_set_iommu+0x82/0xd0 intel_iommu_init+0xe33/0x1039
>>>>> pci_iommu_init+0x9/0x31 do_one_initcall+0x53/0x2f0
>>>>> kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120
>>>>> ret_from_fork+0x1f/0x30 -> #1
>>>>> (&domain->iova_cookie->mutex){+.+.}-{3:3}: lock_acquire+0xd3/0x310
>>>>> __mutex_lock+0x97/0xf10 iommu_setup_dma_ops+0xd7/0x440
>>>>> iommu_probe_device+0xa4/0x180 iommu_bus_notifier+0x2d/0x40
>>>>> notifier_call_chain+0x31/0x90
>>>>> blocking_notifier_call_chain+0x3a/0x50 device_add+0x3c1/0x900
>>>>> pci_device_add+0x255/0x580 pci_scan_single_device+0xa6/0xd0
>>>>> pci_scan_slot+0x7a/0x1b0 pci_scan_child_bus_extend+0x35/0x2a0
>>>>> vmd_probe+0x5cd/0x970 pci_device_probe+0x95/0x110
>>>>> really_probe+0xd6/0x350 __driver_probe_device+0x73/0x170
>>>>> driver_probe_device+0x1a/0x90 __driver_attach+0xbc/0x190
>>>>> bus_for_each_dev+0x72/0xc0 bus_add_driver+0x1bb/0x210
>>>>> driver_register+0x66/0xc0 do_one_initcall+0x53/0x2f0
>>>>> kernel_init_freeable+0x18f/0x1e1 kernel_init+0x11/0x120
>>>>> ret_from_fork+0x1f/0x30 -> #0
>>>>> (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
>>>>> validate_chain+0xb3f/0x2000 __lock_acquire+0x5a4/0xb70
>>>>> lock_acquire+0xd3/0x310 down_read+0x39/0x140
>>>>> blocking_notifier_call_chain+0x20/0x50 device_add+0x3c1/0x900
>>>>> platform_device_add+0x108/0x240 coretemp_cpu_online+0xe1/0x15e
>>>>> [coretemp] cpuhp_invoke_callback+0x181/0x8a0
>>>>> cpuhp_thread_fun+0x188/0x1f0 smpboot_thread_fn+0x1b5/0x260
>>>>> kthread+0xed/0x120 ret_from_fork+0x1f/0x30 other info that might
>>>>> help us debug thi Chain exists of &(&priv->bus_notifier)->rwsem -->
>>>>> cpu_hotplug_lock --> cpuhp_state- Possible unsafe locking scenari
>>>>> CPU0 CPU1 ---- ---- lock(cpuhp_state-up);
>>>>> lock(cpu_hotplug_lock); lock(cpuhp_state-up);
>>>>> lock(&(&priv->bus_notifier)->rwsem); *** DEADLOCK * 2 locks held by
>>>>> cpuhp/0/15: #0: ffffffff82648f10 (cpu_hotplug_lock){++++}-{0:0},
>>>>> at: cpuhp_thread_fun+0x48/0x1f0 #1: ffffffff826490c0
>>>>> (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x48/0x1f0 stack
>>>>> backtrace: CPU: 0 PID: 15 Comm:
>>>>> cpuhp/0 Not tainted 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
>>>>> Hardware name: Intel Corporation Alder Lake Client
>>>>> Platform/AlderLake-P DDR4 RVP, BIOS
>>>>> ADLPFWI1.R00.3135.A00.2203251419 03/25/2022 Call Trace: <TASK>
>>>>> dump_stack_lvl+0x56/0x7f check_noncircular+0x132/0x150
>>>>> validate_chain+0xb3f/0x2000 __lock_acquire+0x5a4/0xb70
>>>>> lock_acquire+0xd3/0x310 ? blocking_notifier_call_chain+0x20/0x50
>>>>> down_read+0x39/0x140 ? blocking_notifier_call_chain+0x20/0x50
>>>>> blocking_notifier_call_chain+0x20/0x50 device_add+0x3c1/0x900 ?
>>>>> dev_set_name+0x4e/0x70 platform_device_add+0x108/0x240
>>>>> coretemp_cpu_online+0xe1/0x15e [coretemp] ?
>>>>> create_core_data+0x550/0x550 [coretemp]
>>>>> cpuhp_invoke_callback+0x181/0x8a0 cpuhp_thread_fun+0x188/0x1f0 ?
>>>>> smpboot_thread_fn+0x1e/0x260 smpboot_thread_fn+0x1b5/0x260 ?
>>>>> sort_range+0x20/0x20 kthread+0xed/0x120 ?
>>>>> kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 </TASK>
>>>>>
>>>>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
>>>>>
>>>>> Signed-off-by: Karolina Drobnik <[email protected]> Cc:
>>>>> Lucas De Marchi <[email protected]> ---
>>>>> drivers/iommu/dma-iommu.c | 17 ++++------------- 1 file changed,
>>>>> 4 insertions(+), 13 deletions(-)
>>>>>
>>>>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>>>>> index 17dd683b2fce..9616b473e4c7 100644 ---
>>>>> a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@
>>>>> -65,7 +65,6 @@ struct iommu_dma_cookie {
>>>>>
>>>>> /* Domain for flush queue callback; NULL if flush queue not in use
>>>>> */ struct iommu_domain *fq_domain; - struct mutex mutex; };
>>>>>
>>>>> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled); @@
>>>>> -312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain
>>>>> *domain) if (!domain->iova_cookie) return -ENOMEM;
>>>>>
>>>>> - mutex_init(&domain->iova_cookie->mutex); return 0; }
>>>>>
>>>>> @@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct
>>>>> iommu_domain *domain, dma_addr_t base, }
>>>>>
>>>>> /* start_pfn is always nonzero for an already-initialised domain
>>>>> */ - mutex_lock(&cookie->mutex); if (iovad->start_pfn) { if (1UL
>>>>> << order != iovad->granule || base_pfn != iovad->start_pfn)
>>>>> { pr_warn("Incompatible range for DMA domain\n"); - ret = -EFAULT;
>>>>> - goto done_unlock; + return -EFAULT; }
>>>>>
>>>>> - ret = 0; - goto done_unlock; + return 0; }
>>>>>
>>>>> init_iova_domain(iovad, 1UL << order, base_pfn); ret =
>>>>> iova_domain_init_rcaches(iovad); if (ret) - goto
>>>>> done_unlock; + return ret;
>>>>>
>>>>> /* If the FQ fails we can simply fall back to strict mode */ if
>>>>> (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
>>>>> domain->type = IOMMU_DOMAIN_DMA;
>>>>>
>>>>> - ret = iova_reserve_iommu_regions(dev, domain); - -done_unlock:
>>>>> - mutex_unlock(&cookie->mutex); - return
>>>>> ret; + return iova_reserve_iommu_regions(dev, domain); }
>>>>>
>>>>> /** -- 2.25.1
>>>>>
Hi Robin,
On Wednesday, 14 September 2022 17:54:36 CEST Robin Murphy wrote:
> On 2022-09-14 16:01, Lucas De Marchi wrote:
> > On Wed, Sep 14, 2022 at 02:40:45PM +0200, Karolina Drobnik wrote:
> >> This reverts commit ac9a5d522bb80be50ea84965699e1c8257d745ce.
> >>
> >> This change introduces a regression on Alder Lake that completely
> >> blocks testing. To enable CI and avoid possible circular locking
> >> warning, revert the patch.
> >
> > We are already on rc5. Are iommu authors involved aware of this issue?
> > We could do this in our "for CI only" branch, but it's equally important
> > that this is fixed for 6.0
> >
> > Cc'ing them.
>
> The lockdep report doesn't make much sense to me - the deadlock cycle
> it's reporting doesn't even involve the mutex added by that commit, and
> otherwise the lock ordering between the IOMMU bus notifier(s) and
> cpu_hotplug_lock has existed for ages.
Indeed, that lockdep report is not quite related, but there are other lockdep
reports in our CI results that better justify the revert.
https://intel-gfx-ci.01.org/tree/drm-tip/TrybotIGT_595/bat-dg2-8/igt@[email protected]
...
<7> [181.565177] [IGT] core_hotunplug: unplugging the device
<7> [181.565372] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling DC_off
<7> [181.565708] i915 0000:03:00.0: [drm:gen9_set_dc_state.part.15 [i915]] Setting DC state from 01 to 00
<7> [181.566060] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_2
<7> [181.566216] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_A
<7> [181.566447] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_B
<7> [181.566607] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_C
<7> [181.566765] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_D
<7> [181.570683] intel_gt_set_wedged called from intel_gt_set_wedged_on_fini+0x9/0x30 [i915]
<7> [181.659480] i915 0000:03:00.0: [drm:drm_client_release] drm_fb_helper
<6> [181.773310] pci 0000:03:00.0: Removing from iommu group 1
<7> [181.774416] [IGT] core_hotunplug: rediscovering the device
<6> [181.775800] pci 0000:03:00.0: [8086:56a0] type 00 class 0x030000
<6> [181.775833] pci 0000:03:00.0: reg 0x10: [mem 0x90000000-0x90ffffff 64bit]
<6> [181.775852] pci 0000:03:00.0: reg 0x18: [mem 0x4000000000-0x43ffffffff 64bit pref]
<6> [181.775886] pci 0000:03:00.0: reg 0x30: [mem 0xffe00000-0xffffffff pref]
<6> [181.776058] pci 0000:03:00.0: ASPM: overriding L1 acceptable latency from 0x0 to 0x7
<6> [181.776073] pci 0000:03:00.0: Video device with shadowed ROM at [mem 0x000c0000-0x000dffff]
<6> [181.776209] pci 0000:03:00.0: PME# supported from D0 D3hot
<6> [181.776869] pci 0000:03:00.0: vgaarb: setting as boot VGA device
<6> [181.776878] pci 0000:03:00.0: vgaarb: bridge control possible
<6> [181.776881] pci 0000:03:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
<6> [181.777052] pci 0000:03:00.0: Adding to iommu group 1
<4> [181.777164]
<4> [181.777169] ======================================================
<4> [181.777176] WARNING: possible circular locking dependency detected
<4> [181.777182] 6.0.0-rc5-CI_DRM_12145-g2dc9ea03abff+ #1 Not tainted
<4> [181.777189] ------------------------------------------------------
<4> [181.777196] core_hotunplug/1240 is trying to acquire lock:
<4> [181.777202] ffff8881029b33b0 (&domain->iova_cookie->mutex){+.+.}-{3:3}, at: iommu_setup_dma_ops+0xd7/0x440
<4> [181.777218]
but task is already holding lock:
<4> [181.777225] ffff8881010c9e78 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x20/0x50
<4> [181.777242]
which lock already depends on the new lock.
<4> [181.777250]
the existing dependency chain (in reverse order) is:
<4> [181.777258]
-> #3 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
<4> [181.777268] lock_acquire+0xd3/0x310
<4> [181.777274] down_read+0x39/0x140
<4> [181.777281] blocking_notifier_call_chain+0x20/0x50
<4> [181.777289] device_add+0x3c1/0x900
<4> [181.777295] platform_device_add+0x108/0x240
<4> [181.777302] coretemp_cpu_online+0xe1/0x15e [coretemp]
<4> [181.777310] cpuhp_invoke_callback+0x181/0x8a0
<4> [181.777318] cpuhp_thread_fun+0x188/0x1f0
<4> [181.777325] smpboot_thread_fn+0x1b5/0x260
<4> [181.777332] kthread+0xed/0x120
<4> [181.777337] ret_from_fork+0x1f/0x30
<4> [181.777343]
-> #2 (cpuhp_state-up){+.+.}-{0:0}:
<4> [181.777352] lock_acquire+0xd3/0x310
<4> [181.777358] cpuhp_thread_fun+0xa6/0x1f0
<4> [181.777364] smpboot_thread_fn+0x1b5/0x260
<4> [181.777370] kthread+0xed/0x120
<4> [181.777375] ret_from_fork+0x1f/0x30
<4> [181.777381]
-> #1 (cpu_hotplug_lock){++++}-{0:0}:
<4> [181.777390] lock_acquire+0xd3/0x310
<4> [181.777395] __cpuhp_state_add_instance+0x43/0x1c0
<4> [181.777402] iova_domain_init_rcaches+0x199/0x1c0
<4> [181.777409] iommu_setup_dma_ops+0x130/0x440
<4> [181.777415] bus_iommu_probe+0x26a/0x2d0
<4> [181.777422] bus_set_iommu+0x82/0xd0
<4> [181.777428] intel_iommu_init+0xe33/0x1039
<4> [181.777435] pci_iommu_init+0x9/0x31
<4> [181.777442] do_one_initcall+0x53/0x2f0
<4> [181.777448] kernel_init_freeable+0x18f/0x1e1
<4> [181.777455] kernel_init+0x11/0x120
<4> [181.777461] ret_from_fork+0x1f/0x30
<4> [181.777467]
-> #0 (&domain->iova_cookie->mutex){+.+.}-{3:3}:
<4> [181.777477] validate_chain+0xb3f/0x2000
<4> [181.777484] __lock_acquire+0x5a4/0xb70
<4> [181.777490] lock_acquire+0xd3/0x310
<4> [181.777495] __mutex_lock+0x97/0xf10
<4> [181.777501] iommu_setup_dma_ops+0xd7/0x440
<4> [181.777507] iommu_probe_device+0xa4/0x180
<4> [181.777514] iommu_bus_notifier+0x2d/0x40
<4> [181.777521] notifier_call_chain+0x31/0x90
<4> [181.777528] blocking_notifier_call_chain+0x3a/0x50
<4> [181.777535] device_add+0x3c1/0x900
<4> [181.777541] pci_device_add+0x255/0x580
<4> [181.777548] pci_scan_single_device+0xa6/0xd0
<4> [181.777555] pci_scan_slot+0x7a/0x1b0
<4> [181.777561] pci_scan_child_bus_extend+0x35/0x2a0
<4> [181.777568] pci_scan_bridge_extend+0x588/0x650
<4> [181.777575] pci_scan_child_bus_extend+0xd7/0x2a0
<4> [181.777582] pci_scan_bridge_extend+0x588/0x650
<4> [181.777589] pci_scan_child_bus_extend+0xd7/0x2a0
<4> [181.777596] pci_scan_bridge_extend+0x588/0x650
<4> [181.777602] pci_scan_child_bus_extend+0xd7/0x2a0
<4> [181.777609] pci_rescan_bus+0xc/0x30
<4> [181.777616] rescan_store+0x60/0x90
<4> [181.777622] kernfs_fop_write_iter+0x121/0x1c0
<4> [181.777630] vfs_write+0x34c/0x4e0
<4> [181.777636] ksys_write+0x57/0xd0
<4> [181.777642] do_syscall_64+0x37/0x90
<4> [181.777648] entry_SYSCALL_64_after_hwframe+0x63/0xcd
<4> [181.777655]
other info that might help us debug this:
<4> [181.777664] Chain exists of:
&domain->iova_cookie->mutex --> cpuhp_state-up --> &(&priv->bus_notifier)->rwsem
<4> [181.777680] Possible unsafe locking scenario:
<4> [181.777686] CPU0 CPU1
<4> [181.777691] ---- ----
<4> [181.777696] lock(&(&priv->bus_notifier)->rwsem);
<4> [181.777703] lock(cpuhp_state-up);
<4> [181.777710] lock(&(&priv->bus_notifier)->rwsem);
<4> [181.777719] lock(&domain->iova_cookie->mutex);
<4> [181.777725]
*** DEADLOCK ***
<4> [181.777732] 5 locks held by core_hotunplug/1240:
<4> [181.777738] #0: ffff888106e3c430 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x57/0xd0
<4> [181.777752] #1: ffff888118f92688 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0xee/0x1c0
<4> [181.777764] #2: ffff8881010952a0 (kn->active#405){.+.+}-{0:0}, at: kernfs_fop_write_iter+0xf7/0x1c0
<4> [181.777778] #3: ffffffff827a48c8 (pci_rescan_remove_lock){+.+.}-{3:3}, at: rescan_store+0x54/0x90
<4> [181.777792] #4: ffff8881010c9e78 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at: blocking_notifier_call_chain+0x20/0x50
<4> [181.777807]
stack backtrace:
<4> [181.777813] CPU: 9 PID: 1240 Comm: core_hotunplug Not tainted 6.0.0-rc5-CI_DRM_12145-g2dc9ea03abff+ #1
<4> [181.777824] Hardware name: Intel Corporation CoffeeLake Client Platform/CoffeeLake S UDIMM RVP, BIOS CNLSFWR1.R00.X220.B00.2103302221 03/30/2021
<4> [181.777837] Call Trace:
<4> [181.777840] <TASK>
<4> [181.777844] dump_stack_lvl+0x56/0x7f
<4> [181.777851] check_noncircular+0x132/0x150
<4> [181.777858] ? validate_chain+0x247/0x2000
<4> [181.777867] validate_chain+0xb3f/0x2000
<4> [181.777876] __lock_acquire+0x5a4/0xb70
<4> [181.777883] lock_acquire+0xd3/0x310
<4> [181.777889] ? iommu_setup_dma_ops+0xd7/0x440
<4> [181.777897] __mutex_lock+0x97/0xf10
<4> [181.777903] ? iommu_setup_dma_ops+0xd7/0x440
<4> [181.777910] ? iommu_setup_dma_ops+0xd7/0x440
<4> [181.777918] ? iommu_setup_dma_ops+0xd7/0x440
<4> [181.777924] iommu_setup_dma_ops+0xd7/0x440
<4> [181.777931] ? __mutex_unlock_slowpath+0x3e/0x2b0
<4> [181.777939] iommu_probe_device+0xa4/0x180
<4> [181.777947] iommu_bus_notifier+0x2d/0x40
<4> [181.777953] notifier_call_chain+0x31/0x90
<4> [181.777961] blocking_notifier_call_chain+0x3a/0x50
<4> [181.777968] device_add+0x3c1/0x900
<4> [181.777974] ? _raw_read_unlock+0x24/0x40
<4> [181.777980] ? region_intersects+0x95/0xb0
<4> [181.777988] pci_device_add+0x255/0x580
<4> [181.777994] ? pci_setup_device.cold.56+0x318/0x5b6
<4> [181.778003] pci_scan_single_device+0xa6/0xd0
<4> [181.778010] pci_scan_slot+0x7a/0x1b0
<4> [181.778017] pci_scan_child_bus_extend+0x35/0x2a0
<4> [181.778026] pci_scan_bridge_extend+0x588/0x650
<4> [181.778034] pci_scan_child_bus_extend+0xd7/0x2a0
<4> [181.778042] pci_scan_bridge_extend+0x588/0x650
<4> [181.778051] pci_scan_child_bus_extend+0xd7/0x2a0
<4> [181.778059] pci_scan_bridge_extend+0x588/0x650
<4> [181.778068] pci_scan_child_bus_extend+0xd7/0x2a0
<4> [181.778076] pci_rescan_bus+0xc/0x30
<4> [181.778082] rescan_store+0x60/0x90
<4> [181.778089] kernfs_fop_write_iter+0x121/0x1c0
<4> [181.778096] vfs_write+0x34c/0x4e0
<4> [181.778104] ksys_write+0x57/0xd0
<4> [181.778111] do_syscall_64+0x37/0x90
<4> [181.778117] entry_SYSCALL_64_after_hwframe+0x63/0xcd
<4> [181.778123] RIP: 0033:0x7f43eb46e2f7
<4> [181.778129] Code: 75 05 48 83 c4 58 c3 e8 f7 33 ff ff 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
<4> [181.778148] RSP: 002b:00007ffe001a12a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
<4> [181.778158] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f43eb46e2f7
<4> [181.778166] RDX: 0000000000000001 RSI: 0000559c8480518a RDI: 0000000000000005
<4> [181.778173] RBP: 0000559c8480518a R08: 0000000000000000 R09: 0000000000000000
<4> [181.778181] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
<4> [181.778189] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
<4> [181.778200] </TASK>
...
The same test on kernel with the revert applied
(https://intel-gfx-ci.01.org/tree/drm-tip/TrybotIGT_598/bat-dg2-8/igt@[email protected]):
...
<7> [172.263693] [IGT] core_hotunplug: unplugging the device
<7> [172.263862] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling DC_off
<7> [172.264185] i915 0000:03:00.0: [drm:gen9_set_dc_state.part.15 [i915]] Setting DC state from 01 to 00
<7> [172.264535] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_2
<7> [172.264707] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_A
<7> [172.264931] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_B
<7> [172.265098] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_C
<7> [172.265264] i915 0000:03:00.0: [drm:intel_power_well_enable [i915]] enabling PW_D
<7> [172.268842] intel_gt_set_wedged called from intel_gt_set_wedged_on_fini+0x9/0x30 [i915]
<7> [172.346115] i915 0000:03:00.0: [drm:drm_client_release] drm_fb_helper
<6> [172.467208] pci 0000:03:00.0: Removing from iommu group 1
<7> [172.468877] [IGT] core_hotunplug: rediscovering the device
<6> [172.470464] pci 0000:03:00.0: [8086:56a0] type 00 class 0x030000
<6> [172.470504] pci 0000:03:00.0: reg 0x10: [mem 0x90000000-0x90ffffff 64bit]
<6> [172.470527] pci 0000:03:00.0: reg 0x18: [mem 0x4000000000-0x43ffffffff 64bit pref]
<6> [172.470567] pci 0000:03:00.0: reg 0x30: [mem 0xffe00000-0xffffffff pref]
<6> [172.470821] pci 0000:03:00.0: ASPM: overriding L1 acceptable latency from 0x0 to 0x7
<6> [172.470840] pci 0000:03:00.0: Video device with shadowed ROM at [mem 0x000c0000-0x000dffff]
<6> [172.471014] pci 0000:03:00.0: PME# supported from D0 D3hot
<6> [172.471890] pci 0000:03:00.0: vgaarb: setting as boot VGA device
<6> [172.471903] pci 0000:03:00.0: vgaarb: bridge control possible
<6> [172.471906] pci 0000:03:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
<6> [172.472135] pci 0000:03:00.0: Adding to iommu group 1
<6> [172.472911] pci 0000:03:00.0: BAR 2: assigned [mem 0x4000000000-0x43ffffffff 64bit pref]
<6> [172.472932] pci 0000:03:00.0: BAR 0: assigned [mem 0x90000000-0x90ffffff 64bit]
<7> [172.474922] i915 0000:03:00.0: [drm:i915_driver_probe [i915]] WOPCM: 2048K
...
For completeness of the picture, here is a list of kernel commits present in
TrybotIGT_598 and not present in TrybotIGT_595:
a7c48a0ab87ae52c087d663e83e56b8225ac4cce drm/panel: simple: Fix innolux_g121i1_l01 bus_format
521a547ced6477c54b4b0cc206000406c221b4d6 Linux 6.0-rc6
c989a62484ad75e0a06f2ffe67886e7cb6d41659 drm/gma500: Call acpi_video_register_backlight()
a7b98d4dfe68654641d56cdc7eace2c36be93a2d drm/gma500: Don't register backlight when another backlight should be used
fbf3093466d05461e3f307ffe6b1150daa4b065b drm/gma500: Use backlight_get_brightness() to get the brightness
dec4ddbe1d4a4414092309611cc97e6b9dc7ec3f drm/gma500: Change registered backlight device type to raw/native
1f90b1232773249d924868bec3c31525a69fd482 drm/gma500: Refactor backlight support (v2)
9bd3f728223ebcfef8e9d087bdd142f0e388215d io_uring/opdef: rename SENDZC_NOTIF to SEND_ZC
e3366e0234971a09f0e16f0e6fa16f4cbae45e47 io_uring/net: fix zc fixed buf lifetime
e10ea7b9b90219da305a16b3c1252169715a807b drm: panel-orientation-quirks: Add quirk for Aya Neo Air
74f481f187ce8b37ec5143cee19147da5243009c drm/gma500: Remove unnecessary suspend/resume wrappers
672c473576ca5c9f5a40ac848c938e6898a5aac8 drm/gma500: Rewrite power management code
d35a4bf66079b92e232ac85b08f19312be9b7eca drm/gma500: Remove a couple of not useful function wrappers
f3b173e9094f5b02fb92d641e3e71fee0bcda73a drm/gma500: Remove never set dev_priv->rpm_enabled flag
49da26d7b418cfc99ad2473a2e3dee2e08c5ba4a drm/gma500: Remove runtime_allowed dead code in psb_unlocked_ioctl()
9b6a16575ebf23a98a9ff84aedde9f3b25731714 drm/gma500: Fix (vblank) IRQs not working after suspend/resume
2830ca9e5b98bee82f1d1e284ce23fe7fb244ea8 drm/vboxvideo: fix repeated words in comments
770e19076065e079a32f33eb11be2057c87f1cde drm: panel-orientation-quirks: Add quirk for Anbernic Win600
8401bd361f5991ccfe9377e502fa37203ad70320 drm/plane-helper: Add a drm_plane_helper_atomic_check() helper
01f0ce3e859619ea84104d668a87ace924bd12df drm/i915/guc: Fix release build bug in 'remove log size module parameters'
bc79ef6d5a223ea59acf874f0493b79c835b17d4 Revert "iommu/dma: Fix race condition during iova_domain initialization"
835a4d18353492577093eff7cb6fa866f6e7014f drm/i915/rps: Freq caps for MTL
1551b9164f6194ffee78935d1ff515f697619483 drm/i915/mtl: PERF_LIMIT_REASONS changes for MTL
fe5979665f6408092ff6072dc894b74a192cbb53 drm/i915/debugfs: Add perf_limit_reasons in debugfs
f569ae759472fbe1f6fdddc7398360d43fdcc199 drm/i915: Handle all GTs on driver (un)load paths
4b3823ff7fa5bd000aa73384ec1f611980d00855 drm/i915: Make GEM suspend all GTs
e23a40040819a7a3fcda3c6cedaeff80ad20c231 drm/i915: Make GEM resume all engines
78a033433a5ae4fee85511ee075bc9a48312c79e drm/i915/gt: Cleanup partial engine discovery failures
e4dc45b1848bc6bcac31eb1b4ccdd7f6718b3c86 drm/sched: Use parent fence instead of finished
b96fb1e724ae6839d5bffcf42dd3503db7cc7df5 dma-buf: dma_fence_wait must enable signaling
d62c43a953ce02d54521ec06217d0c2ed6d489af dma-buf: Enable signaling on fence for selftests
c85d00d4fd8b98ea4d16817f397a4de5e177afd6 dma-buf: set signaling bit for the stub fence
6ad9aa476ce23be45de9dcb03edcdbfdf6117c25 dma-buf: Remove the signaled bit status check
fc7222c3a9f56271fba02aabbfbae999042f1679 io_uring/msg_ring: check file type before putting
c4fa368466cc1b60bb92f867741488930ddd6034 blk-lib: fix blkdev_issue_secure_erase
805ce8614958c925877ba6b6dc26cdf9f8800474 parisc: Allow CONFIG_64BIT with ARCH=parisc
e359b70cc1c51138e166bd4a560e5c5995369a99 parisc: remove obsolete manual allocation aligning in iosapic
c297561bc98ad0f2a37ce0178ee3ba89ab586d70 pinctrl: ocelot: Fix interrupt controller
09eed5a1ed3c752892663976837eb4244c2f1984 gpio: mt7621: Make the irqchip immutable
8af8aed97bebe8b26a340da5236e277c3d84a8ec cifs: update internal module number
621a41ae0834cec9cab312d600d2b9de41dc6eac cifs: add missing spinlock around tcon refcount
bedc8f76b3539ac4f952114b316bcc2251e808ce cifs: always initialize struct msghdr smb_msg completely
17d3df38dc5f4cec9b0ac6eb79c1859b6e2693a4 cifs: don't send down the destination address to sendmsg for a SOCK_STREAM
56f99b8d06ef1ed1c9730948f9f05ac2b930a20b block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait
de11663b75b0a8f1cfeb00d3b4acec9bd5a49cad dt-bindings: pinctrl: qcom: drop non-working codeaurora.org emails
969d373228f6624de87aa0982d89a756e8e77471 dt-bindings: power: qcom,rpmpd: drop non-working codeaurora.org emails
94e9bc73d85aa6ecfe249e985ff57abe0ab35f34 gpio: ixp4xx: Make irqchip immutable
1660c679d6d4779fbce937d0c9dc2af56e66e62d MAINTAINERS: Update HiSilicon GPIO Driver maintainer
62bb0647b14646fa6c9aa25ecdf67ad18f13523c io_uring/rw: fix error'ed retry return values
da3b1c294d470b2cf3c7046cc9e0d5c66f0a6c65 dt-bindings: apple,aic: Fix required item "apple,fiq-index" in affinity description
95363747a6f39e88a3052fcf6ce6237769495ce0 tools/include/uapi: Fix <asm/errno.h> for parisc and xtensa
4b9d1bc7911c9d9159c4881455c584cde99fbb19 Input: hp_sdc: fix spelling typo in comment
38238be4e881a5d0abbe4872b4cd6ed790be06c8 parisc: ccio-dma: Add missing iounmap in error path in ccio_probe()
bfbfb6182ad1d7d184b16f25165faad879147f79 nfsd_splice_actor(): handle compound pages
7500a99281dfed2d4a84771c933bcb9e17af279b cifs: revalidate mapping when doing direct writes
00801cd92d91e94aa04d687f9bb9a9104e7c3d46 NFSD: fix regression with setting ACLs.
13bd9014180425f5a35eaf3735971d582c299292 Revert "SUNRPC: Remove unreachable error condition"
d7a5118635e725d195843bda80cc5c964d93ef31 NFSv4.2: Update mode bits after ALLOCATE and DEALLOCATE
12ef2508f33db1654de2f22f75dd868141b8b305 dt-bindings: interconnect: fsl,imx8m-noc: drop Leonard Crestez
279c12df8d2efb28def9d037f288cbfb97c30fe2 gpio: mpc8xxx: Fix support for IRQ_TYPE_LEVEL_LOW flow_type in mpc85xx
f0880e2cb7e1f8039a048fdd01ce45ab77247221 Drivers: hv: Never allocate anything besides framebuffer from framebuffer memory region
2a8a8afba0c3053d0ea8686182f6b2104293037e Drivers: hv: Always reserve framebuffer region for Gen1 VMs
8409fe92d88c332923130149fe209d1c882b286e PCI: Move PCI_VENDOR_ID_MICROSOFT/PCI_DEVICE_ID_HYPERV_VIDEO definitions to pci_ids.h
2258954234db7530e9d86bb32cd6ad54485ff926 tools: hv: kvp: remove unnecessary (void*) conversions
676576d164b34a98589a9efee85f57240c07fef3 Drivers: hv: remove duplicate word in a comment
2a9d683b48c8a87e61a4215792d44c90bcbbb536 NFSv4: Turn off open-by-filehandle and NFS re-export for NFSv4.0
17814819ac9829a437e06fbb5c7056a1f4f893da SUNRPC: Fix call completion races with call_decode()
76648c867c6c03b8a468d9c9222025873ecc613d pinctrl: sunxi: Fix name for A100 R_PIO
40bfe7a86d84cf08ac6a8fe2f0c8bf7a43edd110 of/device: Fix up of_dma_configure_id() stub
b871656aa4f54e04207f62bdd0d7572be1d86b36 pinctrl: rockchip: Enhance support for IRQ_TYPE_EDGE_BOTH
48ec73395887694f13c9452b4dcfb43710451757 pinctrl: qcom: sc8180x: Fix wrong pin numbers
6124cec530c7d8faab96d340ab2df5161e5d1c8a pinctrl: qcom: sc8180x: Fix gpio_wakeirq_map
c6a43fb3487f7e040170e60cdb9b030c669e9cf5 MAINTAINERS: Update email of Neil Armstrong
2f945a792f67815abca26fa8a5e863ccf3fa1181 of: fdt: fix off-by-one error in unflatten_dt_nodes()
f15f39fabed2248311607445ddfa6dba63abebb9 tools: hv: Remove an extraneous "the"
f1f63cbb705dc38826369496c6fc12c1b8db1324 drm/hyperv: Fix an error handling path in hyperv_vmbus_probe()
Thanks,
Janusz
> Has lockdep somehow got multiple
> different and unrelated bus notifiers mixed up, maybe?
>
> FWIW nobody else has reported anything, and that mutex addresses a
> real-world concurrency issue, so I'm not convinced a revert is
> appropriate without at least a much clearer justification.
>
> Robin.
>
> > thanks
> > Lucas De Marchi
> >
> >>
> >> kernel log:
> >>
> >> ======================================================
> >> WARNING: possible circular locking dependency detected
> >> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1 Not tainted
> >> ------------------------------------------------------
> >> cpuhp/0/15 is trying to acquire lock:
> >> ffff8881013df278 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}, at:
> >> blocking_notifier_call_chain+0x20/0x50
> >> but task is already holding lock:
> >> ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
> >> cpuhp_thread_fun+0x48/0x1f0
> >> which lock already depends on the new loc
> >> the existing dependency chain (in reverse order) is:
> >> -> #3 (cpuhp_state-up){+.+.}-{0:0}:
> >> lock_acquire+0xd3/0x310
> >> cpuhp_thread_fun+0xa6/0x1f0
> >> smpboot_thread_fn+0x1b5/0x260
> >> kthread+0xed/0x120
> >> ret_from_fork+0x1f/0x30
> >> -> #2 (cpu_hotplug_lock){++++}-{0:0}:
> >> lock_acquire+0xd3/0x310
> >> __cpuhp_state_add_instance+0x43/0x1c0
> >> iova_domain_init_rcaches+0x199/0x1c0
> >> iommu_setup_dma_ops+0x130/0x440
> >> bus_iommu_probe+0x26a/0x2d0
> >> bus_set_iommu+0x82/0xd0
> >> intel_iommu_init+0xe33/0x1039
> >> pci_iommu_init+0x9/0x31
> >> do_one_initcall+0x53/0x2f0
> >> kernel_init_freeable+0x18f/0x1e1
> >> kernel_init+0x11/0x120
> >> ret_from_fork+0x1f/0x30
> >> -> #1 (&domain->iova_cookie->mutex){+.+.}-{3:3}:
> >> lock_acquire+0xd3/0x310
> >> __mutex_lock+0x97/0xf10
> >> iommu_setup_dma_ops+0xd7/0x440
> >> iommu_probe_device+0xa4/0x180
> >> iommu_bus_notifier+0x2d/0x40
> >> notifier_call_chain+0x31/0x90
> >> blocking_notifier_call_chain+0x3a/0x50
> >> device_add+0x3c1/0x900
> >> pci_device_add+0x255/0x580
> >> pci_scan_single_device+0xa6/0xd0
> >> pci_scan_slot+0x7a/0x1b0
> >> pci_scan_child_bus_extend+0x35/0x2a0
> >> vmd_probe+0x5cd/0x970
> >> pci_device_probe+0x95/0x110
> >> really_probe+0xd6/0x350
> >> __driver_probe_device+0x73/0x170
> >> driver_probe_device+0x1a/0x90
> >> __driver_attach+0xbc/0x190
> >> bus_for_each_dev+0x72/0xc0
> >> bus_add_driver+0x1bb/0x210
> >> driver_register+0x66/0xc0
> >> do_one_initcall+0x53/0x2f0
> >> kernel_init_freeable+0x18f/0x1e1
> >> kernel_init+0x11/0x120
> >> ret_from_fork+0x1f/0x30
> >> -> #0 (&(&priv->bus_notifier)->rwsem){++++}-{3:3}:
> >> validate_chain+0xb3f/0x2000
> >> __lock_acquire+0x5a4/0xb70
> >> lock_acquire+0xd3/0x310
> >> down_read+0x39/0x140
> >> blocking_notifier_call_chain+0x20/0x50
> >> device_add+0x3c1/0x900
> >> platform_device_add+0x108/0x240
> >> coretemp_cpu_online+0xe1/0x15e [coretemp]
> >> cpuhp_invoke_callback+0x181/0x8a0
> >> cpuhp_thread_fun+0x188/0x1f0
> >> smpboot_thread_fn+0x1b5/0x260
> >> kthread+0xed/0x120
> >> ret_from_fork+0x1f/0x30
> >> other info that might help us debug thi
> >> Chain exists of &(&priv->bus_notifier)->rwsem -->
> >> cpu_hotplug_lock --> cpuhp_state-
> >> Possible unsafe locking scenari
> >> CPU0 CPU1
> >> ---- ----
> >> lock(cpuhp_state-up);
> >> lock(cpu_hotplug_lock);
> >> lock(cpuhp_state-up);
> >> lock(&(&priv->bus_notifier)->rwsem);
> >> *** DEADLOCK *
> >> 2 locks held by cpuhp/0/15:
> >> #0: ffffffff82648f10 (cpu_hotplug_lock){++++}-{0:0}, at:
> >> cpuhp_thread_fun+0x48/0x1f0
> >> #1: ffffffff826490c0 (cpuhp_state-up){+.+.}-{0:0}, at:
> >> cpuhp_thread_fun+0x48/0x1f0
> >> stack backtrace:
> >> CPU: 0 PID: 15 Comm: cpuhp/0 Not tainted
> >> 6.0.0-rc5-CI_DRM_12132-g6c93e979e542+ #1
> >> Hardware name: Intel Corporation Alder Lake Client
> >> Platform/AlderLake-P DDR4 RVP, BIOS ADLPFWI1.R00.3135.A00.2203251419
> >> 03/25/2022
> >> Call Trace:
> >> <TASK>
> >> dump_stack_lvl+0x56/0x7f
> >> check_noncircular+0x132/0x150
> >> validate_chain+0xb3f/0x2000
> >> __lock_acquire+0x5a4/0xb70
> >> lock_acquire+0xd3/0x310
> >> ? blocking_notifier_call_chain+0x20/0x50
> >> down_read+0x39/0x140
> >> ? blocking_notifier_call_chain+0x20/0x50
> >> blocking_notifier_call_chain+0x20/0x50
> >> device_add+0x3c1/0x900
> >> ? dev_set_name+0x4e/0x70
> >> platform_device_add+0x108/0x240
> >> coretemp_cpu_online+0xe1/0x15e [coretemp]
> >> ? create_core_data+0x550/0x550 [coretemp]
> >> cpuhp_invoke_callback+0x181/0x8a0
> >> cpuhp_thread_fun+0x188/0x1f0
> >> ? smpboot_thread_fn+0x1e/0x260
> >> smpboot_thread_fn+0x1b5/0x260
> >> ? sort_range+0x20/0x20
> >> kthread+0xed/0x120
> >> ? kthread_complete_and_exit+0x20/0x20
> >> ret_from_fork+0x1f/0x30
> >> </TASK>
> >>
> >> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6641
> >>
> >> Signed-off-by: Karolina Drobnik <[email protected]>
> >> Cc: Lucas De Marchi <[email protected]>
> >> ---
> >> drivers/iommu/dma-iommu.c | 17 ++++-------------
> >> 1 file changed, 4 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> >> index 17dd683b2fce..9616b473e4c7 100644
> >> --- a/drivers/iommu/dma-iommu.c
> >> +++ b/drivers/iommu/dma-iommu.c
> >> @@ -65,7 +65,6 @@ struct iommu_dma_cookie {
> >>
> >> /* Domain for flush queue callback; NULL if flush queue not in use */
> >> struct iommu_domain *fq_domain;
> >> - struct mutex mutex;
> >> };
> >>
> >> static DEFINE_STATIC_KEY_FALSE(iommu_deferred_attach_enabled);
> >> @@ -312,7 +311,6 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
> >> if (!domain->iova_cookie)
> >> return -ENOMEM;
> >>
> >> - mutex_init(&domain->iova_cookie->mutex);
> >> return 0;
> >> }
> >>
> >> @@ -563,33 +561,26 @@ static int iommu_dma_init_domain(struct
> >> iommu_domain *domain, dma_addr_t base,
> >> }
> >>
> >> /* start_pfn is always nonzero for an already-initialised domain */
> >> - mutex_lock(&cookie->mutex);
> >> if (iovad->start_pfn) {
> >> if (1UL << order != iovad->granule ||
> >> base_pfn != iovad->start_pfn) {
> >> pr_warn("Incompatible range for DMA domain\n");
> >> - ret = -EFAULT;
> >> - goto done_unlock;
> >> + return -EFAULT;
> >> }
> >>
> >> - ret = 0;
> >> - goto done_unlock;
> >> + return 0;
> >> }
> >>
> >> init_iova_domain(iovad, 1UL << order, base_pfn);
> >> ret = iova_domain_init_rcaches(iovad);
> >> if (ret)
> >> - goto done_unlock;
> >> + return ret;
> >>
> >> /* If the FQ fails we can simply fall back to strict mode */
> >> if (domain->type == IOMMU_DOMAIN_DMA_FQ && iommu_dma_init_fq(domain))
> >> domain->type = IOMMU_DOMAIN_DMA;
> >>
> >> - ret = iova_reserve_iommu_regions(dev, domain);
> >> -
> >> -done_unlock:
> >> - mutex_unlock(&cookie->mutex);
> >> - return ret;
> >> + return iova_reserve_iommu_regions(dev, domain);
> >> }
> >>
> >> /**
> >>
>