This patch series fixes a miscellaneous collection of bugs that all add up to all our mock selftests throwing dmesg warnings in CI. As can be seen from "drm/i915: Always call i915_globals_exit() from i915_exit()", it's especially fun since those warnings don't always show up in the selftests but can show up in other random IGTs depending on test execution order.
Cc: Daniel Vetter daniel.vetter@ffwll.ch
Jason Ekstrand (6): drm/i915: Call i915_globals_exit() after i915_pmu_exit() drm/i915: Call i915_globals_exit() if pci_register_device() fails drm/i915: Always call i915_globals_exit() from i915_exit() drm/ttm: Force re-init if ttm_global_init() fails drm/ttm: Initialize debugfs from ttm_global_init() drm/i915: Make the kmem slab for i915_buddy_block a global
drivers/gpu/drm/i915/i915_buddy.c | 44 ++++++++++++++++++++++------- drivers/gpu/drm/i915/i915_buddy.h | 3 +- drivers/gpu/drm/i915/i915_globals.c | 6 ++-- drivers/gpu/drm/i915/i915_pci.c | 33 +++++++++++++++++----- drivers/gpu/drm/ttm/ttm_device.c | 14 +++++++++ drivers/gpu/drm/ttm/ttm_module.c | 4 --- 6 files changed, 80 insertions(+), 24 deletions(-)
We should tear down in the opposite order we set up.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com --- drivers/gpu/drm/i915/i915_pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 67696d7522718..50ed93b03e582 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1244,8 +1244,8 @@ static void __exit i915_exit(void)
i915_perf_sysctl_unregister(); pci_unregister_driver(&i915_pci_driver); - i915_globals_exit(); i915_pmu_exit(); + i915_globals_exit(); }
module_init(i915_init);
In the unlikely event that pci_register_device() fails, we were tearing down our PMU setup but not globals. This leaves a bunch of memory slabs lying around.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch --- drivers/gpu/drm/i915/i915_globals.c | 4 ++-- drivers/gpu/drm/i915/i915_pci.c | 1 + 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_globals.c b/drivers/gpu/drm/i915/i915_globals.c index 77f1911c463b8..87267e1d2ad92 100644 --- a/drivers/gpu/drm/i915/i915_globals.c +++ b/drivers/gpu/drm/i915/i915_globals.c @@ -138,7 +138,7 @@ void i915_globals_unpark(void) atomic_inc(&active); }
-static void __exit __i915_globals_flush(void) +static void __i915_globals_flush(void) { atomic_inc(&active); /* skip shrinking */
@@ -148,7 +148,7 @@ static void __exit __i915_globals_flush(void) atomic_dec(&active); }
-void __exit i915_globals_exit(void) +void i915_globals_exit(void) { GEM_BUG_ON(atomic_read(&active));
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 50ed93b03e582..4e627b57d31a2 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1230,6 +1230,7 @@ static int __init i915_init(void) err = pci_register_driver(&i915_pci_driver); if (err) { i915_pmu_exit(); + i915_globals_exit(); return err; }
On Mon, Jul 19, 2021 at 01:30:43PM -0500, Jason Ekstrand wrote:
In the unlikely event that pci_register_device() fails, we were tearing down our PMU setup but not globals. This leaves a bunch of memory slabs lying around.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/i915/i915_globals.c | 4 ++-- drivers/gpu/drm/i915/i915_pci.c | 1 + 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_globals.c b/drivers/gpu/drm/i915/i915_globals.c index 77f1911c463b8..87267e1d2ad92 100644 --- a/drivers/gpu/drm/i915/i915_globals.c +++ b/drivers/gpu/drm/i915/i915_globals.c @@ -138,7 +138,7 @@ void i915_globals_unpark(void) atomic_inc(&active); }
-static void __exit __i915_globals_flush(void) +static void __i915_globals_flush(void) { atomic_inc(&active); /* skip shrinking */
@@ -148,7 +148,7 @@ static void __exit __i915_globals_flush(void) atomic_dec(&active); }
-void __exit i915_globals_exit(void) +void i915_globals_exit(void) { GEM_BUG_ON(atomic_read(&active));
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 50ed93b03e582..4e627b57d31a2 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1230,6 +1230,7 @@ static int __init i915_init(void) err = pci_register_driver(&i915_pci_driver); if (err) { i915_pmu_exit();
i915_globals_exit();-- 2.31.1
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch --- drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false; + static int __init i915_init(void) { bool use_kms = true; int err;
+ i915_fully_loaded = false; + err = i915_globals_init(); if (err) return err;
+ /* i915_mock_selftests() only returns zero if no mock subtests were + * run. If we get any non-zero error code, we return early here. + * We always return success because selftests may have allocated + * objects from slabs which will get cleaned up by i915_exit(). We + * could attempt to clean up immediately and fail module load but, + * thanks to interactions with other parts of the kernel (struct + * file, in particular), it's safer to let the module fully load + * and then clean up on unload. + */ err = i915_mock_selftests(); if (err) - return err > 0 ? 0 : err; + return 0;
/* * Enable KMS by default, unless explicitly overriden by @@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
+ /* After this point, i915_init() must either fully succeed or + * properly tear everything down and fail. We don't have separate + * flags for each set-up bit. + */ + i915_fully_loaded = true; + i915_pmu_init();
err = pci_register_driver(&i915_pci_driver); @@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) { - if (!i915_pci_driver.driver.owner) - return; - - i915_perf_sysctl_unregister(); - pci_unregister_driver(&i915_pci_driver); - i915_pmu_exit(); + if (i915_fully_loaded) { + i915_perf_sysctl_unregister(); + pci_unregister_driver(&i915_pci_driver); + i915_pmu_exit(); + } i915_globals_exit(); }
On 19/07/2021 19:30, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
Story checks out but I totally don't get why it wouldn't be noticed until now. Was it perhaps part of the selfetsts contract that a reboot is required after failure?
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
Nasty. Wasn't visible while globals memory leak was "in place". :I
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
When you say "couple of syscall boundaries" you mean exactly two (module init/unload) or there is more to it? Like why "couple" is needed and not just that the module load syscall has exited? That part sounds potentially dodgy. What mechanism is used by the delayed flush?
Have you checked how this change interacts with the test runner and CI?
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
No need to initialize.
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;
Ditto.
err = i915_globals_init(); if (err) return err;
/* i915_mock_selftests() only returns zero if no mock subtests were
/* * Please use this multi line comment style in i915. */
* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/
return err > 0 ? 0 : err;
return 0;/*
- Enable KMS by default, unless explicitly overriden by
@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or
* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;
i915_pmu_init();
err = pci_register_driver(&i915_pci_driver);
@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
- if (!i915_pci_driver.driver.owner)
return;- i915_perf_sysctl_unregister();
- pci_unregister_driver(&i915_pci_driver);
- i915_pmu_exit();
- if (i915_fully_loaded) {
i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();- } i915_globals_exit(); }
Regards,
Tvrtko
On Tue, Jul 20, 2021 at 3:25 AM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 19/07/2021 19:30, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
Story checks out but I totally don't get why it wouldn't be noticed until now. Was it perhaps part of the selfetsts contract that a reboot is required after failure?
No. They do unload the driver, though. They just don't re-load it.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
Nasty. Wasn't visible while globals memory leak was "in place". :I
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
When you say "couple of syscall boundaries" you mean exactly two (module init/unload) or there is more to it? Like why "couple" is needed and not just that the module load syscall has exited? That part sounds potentially dodgy. What mechanism is used by the delayed flush?
Have you checked how this change interacts with the test runner and CI?
By the end of the series, a bunch of tests are fixed. In particular, https://gitlab.freedesktop.org/drm/intel/-/issues/3746
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
No need to initialize.
Already dropped.
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;Ditto.
So, this is something I'm unclear on. I know that static memory gets auto-initialized to zero but what happens if you unload and reload a module? Is it re-initialized to zero? If it is then we can drop this.
err = i915_globals_init(); if (err) return err;/* i915_mock_selftests() only returns zero if no mock subtests were/*
- Please use this multi line comment style in i915.
*/
Done.
* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/ err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0; /* * Enable KMS by default, unless explicitly overriden by@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;i915_pmu_init(); err = pci_register_driver(&i915_pci_driver);@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
if (!i915_pci_driver.driver.owner)return;i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();
if (i915_fully_loaded) {i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();} i915_globals_exit();Regards,
Tvrtko
On 20/07/2021 15:53, Jason Ekstrand wrote:
On Tue, Jul 20, 2021 at 3:25 AM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 19/07/2021 19:30, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
Story checks out but I totally don't get why it wouldn't be noticed until now. Was it perhaps part of the selfetsts contract that a reboot is required after failure?
No. They do unload the driver, though. They just don't re-load it.
I guess that does mean behaviour is reboot after first selftests failure, which would explain why it wasn't caught until now. I was running selftests and I know why I did not see it but that shall not be mentioned here. :)
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
Nasty. Wasn't visible while globals memory leak was "in place". :I
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
When you say "couple of syscall boundaries" you mean exactly two (module init/unload) or there is more to it? Like why "couple" is needed and not just that the module load syscall has exited? That part sounds potentially dodgy. What mechanism is used by the delayed flush?
Have you checked how this change interacts with the test runner and CI?
By the end of the series, a bunch of tests are fixed. In particular, https://gitlab.freedesktop.org/drm/intel/-/issues/3746
Wait but that means CI does reload the driver. So again I totally don't understand why this is only popping up now.
Regards,
Tvrtko
Now you confused me with two replies I forgot to reply to all... :))
On 20/07/2021 15:53, Jason Ekstrand wrote:
On Tue, Jul 20, 2021 at 3:25 AM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
[snip]
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;Ditto.
So, this is something I'm unclear on. I know that static memory gets auto-initialized to zero but what happens if you unload and reload a module? Is it re-initialized to zero? If it is then we can drop this.
Well it's not in memory after it is unloaded so clearly it has to get initialised by the module loader every time it loads it.
Regards,
Tvrtko
Sorry... didn't reply to everything the first time
On Tue, Jul 20, 2021 at 3:25 AM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 19/07/2021 19:30, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
Story checks out but I totally don't get why it wouldn't be noticed until now. Was it perhaps part of the selfetsts contract that a reboot is required after failure?
If there is such a contract, CI doesn't follow it. We unload the driver after selftests but that's it.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
Nasty. Wasn't visible while globals memory leak was "in place". :I
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
When you say "couple of syscall boundaries" you mean exactly two (module init/unload) or there is more to it? Like why "couple" is needed and not just that the module load syscall has exited? That part sounds potentially dodgy. What mechanism is used by the delayed flush?
It only needs the one syscall. I've changed the text to say "at least one syscall boundary". I think that's more clear without providing an exact count which may not be tractable.
Have you checked how this change interacts with the test runner and CI?
As far as I know, there's no interesting interaction here. That said, I did just find that the live selftests fail the modprobe on selftest failure which means they're tearing down globals before a full syscall boundary which may be sketchy. Fortunately, now that we have i915_globals_exit() on the tear-down path if PCI probe fails, if someone ever does do something sketchy there, we'll catch it in dmesg immediately. Maybe we should switch those to always return 0 as well while we're here?
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
No need to initialize.
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;Ditto.
err = i915_globals_init(); if (err) return err;/* i915_mock_selftests() only returns zero if no mock subtests were/*
- Please use this multi line comment style in i915.
*/
* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/ err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0; /* * Enable KMS by default, unless explicitly overriden by@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;i915_pmu_init(); err = pci_register_driver(&i915_pci_driver);@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
if (!i915_pci_driver.driver.owner)return;i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();
if (i915_fully_loaded) {i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();} i915_globals_exit();Regards,
Tvrtko
On 20/07/2021 16:05, Jason Ekstrand wrote:
Sorry... didn't reply to everything the first time
On Tue, Jul 20, 2021 at 3:25 AM Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 19/07/2021 19:30, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
Story checks out but I totally don't get why it wouldn't be noticed until now. Was it perhaps part of the selfetsts contract that a reboot is required after failure?
If there is such a contract, CI doesn't follow it. We unload the driver after selftests but that's it.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
Nasty. Wasn't visible while globals memory leak was "in place". :I
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
When you say "couple of syscall boundaries" you mean exactly two (module init/unload) or there is more to it? Like why "couple" is needed and not just that the module load syscall has exited? That part sounds potentially dodgy. What mechanism is used by the delayed flush?
It only needs the one syscall. I've changed the text to say "at least one syscall boundary". I think that's more clear without providing an exact count which may not be tractable.
One additional syscall _after_ the module load one exits, or just that one? What is the barrier used? I don't think "syscall boundary" is an established synchronisation term so lets understand fully what's happening here.
Regards,
Tvrtko
Have you checked how this change interacts with the test runner and CI?
As far as I know, there's no interesting interaction here. That said, I did just find that the live selftests fail the modprobe on selftest failure which means they're tearing down globals before a full syscall boundary which may be sketchy. Fortunately, now that we have i915_globals_exit() on the tear-down path if PCI probe fails, if someone ever does do something sketchy there, we'll catch it in dmesg immediately. Maybe we should switch those to always return 0 as well while we're here?
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
No need to initialize.
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;Ditto.
err = i915_globals_init(); if (err) return err;/* i915_mock_selftests() only returns zero if no mock subtests were/*
- Please use this multi line comment style in i915.
*/
* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/ err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0; /* * Enable KMS by default, unless explicitly overriden by@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;i915_pmu_init(); err = pci_register_driver(&i915_pci_driver);@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
if (!i915_pci_driver.driver.owner)return;i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();
if (i915_fully_loaded) {i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();} i915_globals_exit();Regards,
Tvrtko
On Mon, Jul 19, 2021 at 01:30:44PM -0500, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;
err = i915_globals_init(); if (err) return err;
/* i915_mock_selftests() only returns zero if no mock subtests were
* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0;
At least the module options still claim that you can run selftests and still load the driver. Which makes sense for perf/hw selftests, since those need the driver, but would result in the same old bug resurfacing that you're trying to fix there.
Is that description just confused and needs some fixing, or do we have a gap here?
Patch itself looks reasonable, with the nits from Tvrtko addressed:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
/* * Enable KMS by default, unless explicitly overriden by @@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or
* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;
i915_pmu_init();
err = pci_register_driver(&i915_pci_driver);
@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
- if (!i915_pci_driver.driver.owner)
return;- i915_perf_sysctl_unregister();
- pci_unregister_driver(&i915_pci_driver);
- i915_pmu_exit();
- if (i915_fully_loaded) {
i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();- } i915_globals_exit();
}
-- 2.31.1
On Tue, Jul 20, 2021 at 9:18 AM Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Jul 19, 2021 at 01:30:44PM -0500, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;err = i915_globals_init(); if (err) return err;/* i915_mock_selftests() only returns zero if no mock subtests were* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/ err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0;At least the module options still claim that you can run selftests and still load the driver. Which makes sense for perf/hw selftests, since those need the driver, but would result in the same old bug resurfacing that you're trying to fix there.
Is that description just confused and needs some fixing, or do we have a gap here?
I don't think there's real need for a fully loaded driver after mock selftests. They exist entirely to run against a mock driver, not the real one.
Patch itself looks reasonable, with the nits from Tvrtko addressed:
Done
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Thanks
--Jason
/* * Enable KMS by default, unless explicitly overriden by@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;i915_pmu_init(); err = pci_register_driver(&i915_pci_driver);@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
if (!i915_pci_driver.driver.owner)return;i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();
if (i915_fully_loaded) {i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();} i915_globals_exit();}
-- 2.31.1
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
On Tue, Jul 20, 2021 at 09:55:22AM -0500, Jason Ekstrand wrote:
On Tue, Jul 20, 2021 at 9:18 AM Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Jul 19, 2021 at 01:30:44PM -0500, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;err = i915_globals_init(); if (err) return err;/* i915_mock_selftests() only returns zero if no mock subtests were* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/ err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0;At least the module options still claim that you can run selftests and still load the driver. Which makes sense for perf/hw selftests, since those need the driver, but would result in the same old bug resurfacing that you're trying to fix there.
Is that description just confused and needs some fixing, or do we have a gap here?
I don't think there's real need for a fully loaded driver after mock selftests. They exist entirely to run against a mock driver, not the real one.
Can you pls update the module option help then for the next round? -Daniel
Patch itself looks reasonable, with the nits from Tvrtko addressed:
Done
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Thanks
--Jason
/* * Enable KMS by default, unless explicitly overriden by@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;i915_pmu_init(); err = pci_register_driver(&i915_pci_driver);@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
if (!i915_pci_driver.driver.owner)return;i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();
if (i915_fully_loaded) {i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();} i915_globals_exit();}
-- 2.31.1
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
On Wed, Jul 21, 2021 at 6:26 AM Daniel Vetter daniel@ffwll.ch wrote:
On Tue, Jul 20, 2021 at 09:55:22AM -0500, Jason Ekstrand wrote:
On Tue, Jul 20, 2021 at 9:18 AM Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Jul 19, 2021 at 01:30:44PM -0500, Jason Ekstrand wrote:
If the driver was not fully loaded, we may still have globals lying around. If we don't tear those down in i915_exit(), we'll leak a bunch of memory slabs. This can happen two ways: use_kms = false and if we've run mock selftests. In either case, we have an early exit from i915_init which happens after i915_globals_init() and we need to clean up those globals. While we're here, add an explicit boolean instead of using a random field from i915_pci_device to detect partial loads.
The mock selftests case gets especially sticky. The load isn't entirely a no-op. We actually do quite a bit inside those selftests including allocating a bunch of mock objects and running tests on them. Once all those tests are complete, we exit early from i915_init(). Perviously, i915_init() would return a non-zero error code on failure and a zero error code on success. In the success case, we would get to i915_exit() and check i915_pci_driver.driver.owner to detect if i915_init exited early and do nothing. In the failure case, we would fail i915_init() but there would be no opportunity to clean up globals.
The most annoying part is that you don't actually notice the failure as part of the self-tests since leaking a bit of memory, while bad, doesn't result in anything observable from userspace. Instead, the next time we load the driver (usually for next IGT test), i915_globals_init() gets invoked again, we go to allocate a bunch of new memory slabs, those implicitly create debugfs entries, and debugfs warns that we're trying to create directories and files that already exist. Since this all happens as part of the next driver load, it shows up in the dmesg-warn of whatever IGT test ran after the mock selftests.
While the obvious thing to do here might be to call i915_globals_exit() after selftests, that's not actually safe. The dma-buf selftests call i915_gem_prime_export which creates a file. We call dma_buf_put() on the resulting dmabuf which calls fput() on the file. However, fput() isn't immediate and gets flushed right before syscall returns. This means that all the fput()s from the selftests don't happen until right before the module load syscall used to fire off the selftests returns which is after i915_init(). If we call i915_globals_exit() in i915_init() after selftests, we end up freeing slabs out from under objects which won't get released until fput() is flushed at the end of the module load.
The solution here is to let i915_init() return success early and detect the early success in i915_exit() and only tear down globals and nothing else. This way the module loads successfully, regardless of the success or failure of the tests. Because we've not enumerated any PCI devices, no device nodes are created and it's entirely useless from userspace. The only thing the module does at that point is hold on to a bit of memory until we unload it and i915_exit() is called. Importantly, this means that everything from our selftests has the ability to properly flush out between i915_init() and i915_exit() because there are a couple syscall boundaries in between.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 32eb6bcfdda9 ("drm/i915: Make request allocation caches global") Cc: Daniel Vetter daniel@ffwll.ch
drivers/gpu/drm/i915/i915_pci.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 4e627b57d31a2..24e4e54516936 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -1194,18 +1194,31 @@ static struct pci_driver i915_pci_driver = { .driver.pm = &i915_pm_ops, };
+static bool i915_fully_loaded = false;
static int __init i915_init(void) { bool use_kms = true; int err;
i915_fully_loaded = false;err = i915_globals_init(); if (err) return err;/* i915_mock_selftests() only returns zero if no mock subtests were* run. If we get any non-zero error code, we return early here.* We always return success because selftests may have allocated* objects from slabs which will get cleaned up by i915_exit(). We* could attempt to clean up immediately and fail module load but,* thanks to interactions with other parts of the kernel (struct* file, in particular), it's safer to let the module fully load* and then clean up on unload.*/ err = i915_mock_selftests(); if (err)
return err > 0 ? 0 : err;
return 0;At least the module options still claim that you can run selftests and still load the driver. Which makes sense for perf/hw selftests, since those need the driver, but would result in the same old bug resurfacing that you're trying to fix there.
Is that description just confused and needs some fixing, or do we have a gap here?
I don't think there's real need for a fully loaded driver after mock selftests. They exist entirely to run against a mock driver, not the real one.
Can you pls update the module option help then for the next round?
Done.
-Daniel
Patch itself looks reasonable, with the nits from Tvrtko addressed:
Done
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
Thanks
--Jason
/* * Enable KMS by default, unless explicitly overriden by@@ -1225,6 +1238,12 @@ static int __init i915_init(void) return 0; }
/* After this point, i915_init() must either fully succeed or* properly tear everything down and fail. We don't have separate* flags for each set-up bit.*/i915_fully_loaded = true;i915_pmu_init(); err = pci_register_driver(&i915_pci_driver);@@ -1240,12 +1259,11 @@ static int __init i915_init(void)
static void __exit i915_exit(void) {
if (!i915_pci_driver.driver.owner)return;i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();
if (i915_fully_loaded) {i915_perf_sysctl_unregister();pci_unregister_driver(&i915_pci_driver);i915_pmu_exit();} i915_globals_exit();}
-- 2.31.1
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
If we have a failure, decrement the reference count so that the next call to ttm_global_init() will actually do something instead of assume everything is all set up.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 62b53b37e4b1 ("drm/ttm: use a static ttm_bo_global instance") Cc: Christian König christian.koenig@amd.com --- drivers/gpu/drm/ttm/ttm_device.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index 5f31acec3ad76..519deea8e39b7 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -100,6 +100,8 @@ static int ttm_global_init(void) debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root, &glob->bo_count); out: + if (ret) + --ttm_glob_use_count; mutex_unlock(&ttm_global_mutex); return ret; }
Am 19.07.21 um 20:30 schrieb Jason Ekstrand:
If we have a failure, decrement the reference count so that the next call to ttm_global_init() will actually do something instead of assume everything is all set up.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 62b53b37e4b1 ("drm/ttm: use a static ttm_bo_global instance") Cc: Christian König christian.koenig@amd.com
Good catch, path is Reviewed-by: Christian König christian.koenig@amd.com
drivers/gpu/drm/ttm/ttm_device.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index 5f31acec3ad76..519deea8e39b7 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -100,6 +100,8 @@ static int ttm_global_init(void) debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root, &glob->bo_count); out:
- if (ret)
--ttm_glob_use_count;
We create a bunch of debugfs entries as a side-effect of ttm_global_init() and then never clean them up. This isn't usually a problem because we free the whole debugfs directory on module unload. However, if the global reference count ever goes to zero and then ttm_global_init() is called again, we'll re-create those debugfs entries and debugfs will complain in dmesg that we're creating entries that already exist. This patch fixes this problem by changing the lifetime of the whole TTM debugfs directory to match that of the TTM global state.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net --- drivers/gpu/drm/ttm/ttm_device.c | 12 ++++++++++++ drivers/gpu/drm/ttm/ttm_module.c | 4 ---- 2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index 519deea8e39b7..74e3b460132b3 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -44,6 +44,8 @@ static unsigned ttm_glob_use_count; struct ttm_global ttm_glob; EXPORT_SYMBOL(ttm_glob);
+struct dentry *ttm_debugfs_root; + static void ttm_global_release(void) { struct ttm_global *glob = &ttm_glob; @@ -53,6 +55,7 @@ static void ttm_global_release(void) goto out;
ttm_pool_mgr_fini(); + debugfs_remove(ttm_debugfs_root);
__free_page(glob->dummy_read_page); memset(glob, 0, sizeof(*glob)); @@ -73,6 +76,13 @@ static int ttm_global_init(void)
si_meminfo(&si);
+ ttm_debugfs_root = debugfs_create_dir("ttm", NULL); + if (IS_ERR(ttm_debugfs_root)) { + ret = PTR_ERR(ttm_debugfs_root); + ttm_debugfs_root = NULL; + goto out; + } + /* Limit the number of pages in the pool to about 50% of the total * system memory. */ @@ -100,6 +110,8 @@ static int ttm_global_init(void) debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root, &glob->bo_count); out: + if (ret && ttm_debugfs_root) + debugfs_remove(ttm_debugfs_root); if (ret) --ttm_glob_use_count; mutex_unlock(&ttm_global_mutex); diff --git a/drivers/gpu/drm/ttm/ttm_module.c b/drivers/gpu/drm/ttm/ttm_module.c index 997c458f68a9a..88554f2db11fe 100644 --- a/drivers/gpu/drm/ttm/ttm_module.c +++ b/drivers/gpu/drm/ttm/ttm_module.c @@ -72,17 +72,13 @@ pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp) return tmp; }
-struct dentry *ttm_debugfs_root; - static int __init ttm_init(void) { - ttm_debugfs_root = debugfs_create_dir("ttm", NULL); return 0; }
static void __exit ttm_exit(void) { - debugfs_remove(ttm_debugfs_root); }
module_init(ttm_init);
On Mon, Jul 19, 2021 at 01:30:46PM -0500, Jason Ekstrand wrote:
We create a bunch of debugfs entries as a side-effect of ttm_global_init() and then never clean them up. This isn't usually a problem because we free the whole debugfs directory on module unload. However, if the global reference count ever goes to zero and then ttm_global_init() is called again, we'll re-create those debugfs entries and debugfs will complain in dmesg that we're creating entries that already exist. This patch fixes this problem by changing the lifetime of the whole TTM debugfs directory to match that of the TTM global state.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net
drivers/gpu/drm/ttm/ttm_device.c | 12 ++++++++++++ drivers/gpu/drm/ttm/ttm_module.c | 4 ---- 2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c index 519deea8e39b7..74e3b460132b3 100644 --- a/drivers/gpu/drm/ttm/ttm_device.c +++ b/drivers/gpu/drm/ttm/ttm_device.c @@ -44,6 +44,8 @@ static unsigned ttm_glob_use_count; struct ttm_global ttm_glob; EXPORT_SYMBOL(ttm_glob);
+struct dentry *ttm_debugfs_root;
static void ttm_global_release(void) { struct ttm_global *glob = &ttm_glob; @@ -53,6 +55,7 @@ static void ttm_global_release(void) goto out;
ttm_pool_mgr_fini();
debugfs_remove(ttm_debugfs_root);
__free_page(glob->dummy_read_page); memset(glob, 0, sizeof(*glob));
@@ -73,6 +76,13 @@ static int ttm_global_init(void)
si_meminfo(&si);
- ttm_debugfs_root = debugfs_create_dir("ttm", NULL);
- if (IS_ERR(ttm_debugfs_root)) {
ret = PTR_ERR(ttm_debugfs_root);ttm_debugfs_root = NULL;goto out;- }
- /* Limit the number of pages in the pool to about 50% of the total
*/
- system memory.
@@ -100,6 +110,8 @@ static int ttm_global_init(void) debugfs_create_atomic_t("buffer_objects", 0444, ttm_debugfs_root, &glob->bo_count); out:
- if (ret && ttm_debugfs_root)
debugfs_remove(ttm_debugfs_root);diff --git a/drivers/gpu/drm/ttm/ttm_module.c b/drivers/gpu/drm/ttm/ttm_module.c index 997c458f68a9a..88554f2db11fe 100644 --- a/drivers/gpu/drm/ttm/ttm_module.c +++ b/drivers/gpu/drm/ttm/ttm_module.c @@ -72,17 +72,13 @@ pgprot_t ttm_prot_from_caching(enum ttm_caching caching, pgprot_t tmp) return tmp; }
-struct dentry *ttm_debugfs_root;
static int __init ttm_init(void) {
- ttm_debugfs_root = debugfs_create_dir("ttm", NULL); return 0;
}
static void __exit ttm_exit(void) {
- debugfs_remove(ttm_debugfs_root);
}
I think you can delete these functions and the lines below too, they should be optional. With that:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
-Daniel
module_init(ttm_init);
2.31.1
There's no reason that I can tell why this should be per-i915_buddy_mm and doing so causes KMEM_CACHE to throw dmesg warnings because it tries to create a debugfs entry with the name i915_buddy_block multiple times. We could handle this by carefully giving each slab its own name but that brings its own pain because then we have to store that string somewhere and manage the lifetimes of the different slabs. The most likely outcome would be a global atomic which we increment to get a new name or something like that.
The much easier solution is to use the i915_globals system like we do for every other slab in i915. This ensures that we have exactly one of them for each i915 driver load and it gets neatly created on module load and destroyed on module unload. Using the globals system also means that its now tied into the shrink handler so we can properly respond to low-memory situations.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Fixes: 88be9a0a06b7 ("drm/i915/ttm: add ttm_buddy_man") Cc: Matthew Auld matthew.auld@intel.com --- drivers/gpu/drm/i915/i915_buddy.c | 44 ++++++++++++++++++++++------- drivers/gpu/drm/i915/i915_buddy.h | 3 +- drivers/gpu/drm/i915/i915_globals.c | 2 ++ 3 files changed, 38 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_buddy.c b/drivers/gpu/drm/i915/i915_buddy.c index 29dd7d0310c1f..911feedad4513 100644 --- a/drivers/gpu/drm/i915/i915_buddy.c +++ b/drivers/gpu/drm/i915/i915_buddy.c @@ -8,8 +8,14 @@ #include "i915_buddy.h"
#include "i915_gem.h" +#include "i915_globals.h" #include "i915_utils.h"
+static struct i915_global_buddy { + struct i915_global base; + struct kmem_cache *slab_blocks; +} global; + static struct i915_buddy_block *i915_block_alloc(struct i915_buddy_mm *mm, struct i915_buddy_block *parent, unsigned int order, @@ -19,7 +25,7 @@ static struct i915_buddy_block *i915_block_alloc(struct i915_buddy_mm *mm,
GEM_BUG_ON(order > I915_BUDDY_MAX_ORDER);
- block = kmem_cache_zalloc(mm->slab_blocks, GFP_KERNEL); + block = kmem_cache_zalloc(global.slab_blocks, GFP_KERNEL); if (!block) return NULL;
@@ -34,7 +40,7 @@ static struct i915_buddy_block *i915_block_alloc(struct i915_buddy_mm *mm, static void i915_block_free(struct i915_buddy_mm *mm, struct i915_buddy_block *block) { - kmem_cache_free(mm->slab_blocks, block); + kmem_cache_free(global.slab_blocks, block); }
static void mark_allocated(struct i915_buddy_block *block) @@ -85,15 +91,11 @@ int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size)
GEM_BUG_ON(mm->max_order > I915_BUDDY_MAX_ORDER);
- mm->slab_blocks = KMEM_CACHE(i915_buddy_block, SLAB_HWCACHE_ALIGN); - if (!mm->slab_blocks) - return -ENOMEM; - mm->free_list = kmalloc_array(mm->max_order + 1, sizeof(struct list_head), GFP_KERNEL); if (!mm->free_list) - goto out_destroy_slab; + return -ENOMEM;
for (i = 0; i <= mm->max_order; ++i) INIT_LIST_HEAD(&mm->free_list[i]); @@ -145,8 +147,6 @@ int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size) kfree(mm->roots); out_free_list: kfree(mm->free_list); -out_destroy_slab: - kmem_cache_destroy(mm->slab_blocks); return -ENOMEM; }
@@ -161,7 +161,6 @@ void i915_buddy_fini(struct i915_buddy_mm *mm)
kfree(mm->roots); kfree(mm->free_list); - kmem_cache_destroy(mm->slab_blocks); }
static int split_block(struct i915_buddy_mm *mm, @@ -410,3 +409,28 @@ int i915_buddy_alloc_range(struct i915_buddy_mm *mm, #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST) #include "selftests/i915_buddy.c" #endif + +static void i915_global_buddy_shrink(void) +{ + kmem_cache_shrink(global.slab_blocks); +} + +static void i915_global_buddy_exit(void) +{ + kmem_cache_destroy(global.slab_blocks); +} + +static struct i915_global_buddy global = { { + .shrink = i915_global_buddy_shrink, + .exit = i915_global_buddy_exit, +} }; + +int __init i915_global_buddy_init(void) +{ + global.slab_blocks = KMEM_CACHE(i915_buddy_block, 0); + if (!global.slab_blocks) + return -ENOMEM; + + i915_global_register(&global.base); + return 0; +} diff --git a/drivers/gpu/drm/i915/i915_buddy.h b/drivers/gpu/drm/i915/i915_buddy.h index 37f8c42071d12..d8f26706de52f 100644 --- a/drivers/gpu/drm/i915/i915_buddy.h +++ b/drivers/gpu/drm/i915/i915_buddy.h @@ -47,7 +47,6 @@ struct i915_buddy_block { * i915_buddy_alloc* and i915_buddy_free* should suffice. */ struct i915_buddy_mm { - struct kmem_cache *slab_blocks; /* Maintain a free list for each order. */ struct list_head *free_list;
@@ -130,4 +129,6 @@ void i915_buddy_free(struct i915_buddy_mm *mm, struct i915_buddy_block *block);
void i915_buddy_free_list(struct i915_buddy_mm *mm, struct list_head *objects);
+int i915_global_buddy_init(void); + #endif diff --git a/drivers/gpu/drm/i915/i915_globals.c b/drivers/gpu/drm/i915/i915_globals.c index 87267e1d2ad92..e57102a4c8d16 100644 --- a/drivers/gpu/drm/i915/i915_globals.c +++ b/drivers/gpu/drm/i915/i915_globals.c @@ -8,6 +8,7 @@ #include <linux/workqueue.h>
#include "i915_active.h" +#include "i915_buddy.h" #include "gem/i915_gem_context.h" #include "gem/i915_gem_object.h" #include "i915_globals.h" @@ -87,6 +88,7 @@ static void __i915_globals_cleanup(void)
static __initconst int (* const initfn[])(void) = { i915_global_active_init, + i915_global_buddy_init, i915_global_context_init, i915_global_gem_context_init, i915_global_objects_init,
dri-devel@lists.freedesktop.org
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Christian König -
Daniel Vetter -
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Tvrtko Ursulin