Messages in this thread | | | Date | Fri, 17 Jul 2020 09:34:34 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH v2] driver core: Fix sleeping in invalid context during device link deletion |
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On Fri, Jul 17, 2020 at 12:13:04AM +0200, Marek Szyprowski wrote: > Hi Saravana, > > On 16.07.2020 23:45, Saravana Kannan wrote: > > Marek and Guenter reported that commit 287905e68dd2 ("driver core: > > Expose device link details in sysfs") caused sleeping/scheduling while > > atomic warnings. > > > > BUG: sleeping function called from invalid context at kernel/locking/mutex.c:935 > > in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 12, name: kworker/0:1 > > 2 locks held by kworker/0:1/12: > > #0: ee8074a8 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x174/0x7dc > > #1: ee921f20 ((work_completion)(&sdp->work)){+.+.}-{0:0}, at: process_one_work+0x174/0x7dc > > Preemption disabled at: > > [<c01b10f0>] srcu_invoke_callbacks+0xc0/0x154 > > ----- 8< ----- SNIP > > [<c064590c>] (device_del) from [<c0645c9c>] (device_unregister+0x24/0x64) > > [<c0645c9c>] (device_unregister) from [<c01b10fc>] (srcu_invoke_callbacks+0xcc/0x154) > > [<c01b10fc>] (srcu_invoke_callbacks) from [<c01493c4>] (process_one_work+0x234/0x7dc) > > [<c01493c4>] (process_one_work) from [<c01499b0>] (worker_thread+0x44/0x51c) > > [<c01499b0>] (worker_thread) from [<c0150bf4>] (kthread+0x158/0x1a0) > > [<c0150bf4>] (kthread) from [<c0100114>] (ret_from_fork+0x14/0x20) > > Exception stack(0xee921fb0 to 0xee921ff8) > > > > This was caused by the device link device being released in the context > > of srcu_invoke_callbacks(). There is no need to wait till the RCU > > callback to release the device link device. So release the device > > earlier and move the call_srcu() into the device release code. That way, > > the memory will get freed only after the device is released AND the RCU > > callback is called. > > > > Fixes: 287905e68dd2 ("driver core: Expose device link details in sysfs") > > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> > > Reported-by: Guenter Roeck <linux@roeck-us.net> > > Signed-off-by: Saravana Kannan <saravanak@google.com> > > --- > > > > v1->v2: > > - Better fix > > - Changed subject > > - v1 is this patch https://lore.kernel.org/lkml/20200716050846.2047110-1-saravanak@google.com/ > > > > Marek and Guenter, > > > > I reproduced the original issue and tested this fix. Seems to work for > > me. Can you confirm? > > Confirmed, this one fixes the issue! :) > Same here.
Tested-by: Guenter Roeck <linux@roeck-us.net>
Guenter
> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> > > > Thanks, > > Saravana > > > > drivers/base/core.c | 45 +++++++++++++++++++++++++++------------------ > > 1 file changed, 27 insertions(+), 18 deletions(-) > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > index 5373ddd029f6..ec16b97d45ed 100644 > > --- a/drivers/base/core.c > > +++ b/drivers/base/core.c > > @@ -306,10 +306,34 @@ static struct attribute *devlink_attrs[] = { > > }; > > ATTRIBUTE_GROUPS(devlink); > > > > +static void device_link_free(struct device_link *link) > > +{ > > + while (refcount_dec_not_one(&link->rpm_active)) > > + pm_runtime_put(link->supplier); > > + > > + put_device(link->consumer); > > + put_device(link->supplier); > > + kfree(link); > > +} > > + > > +#ifdef CONFIG_SRCU > > +static void __device_link_free_srcu(struct rcu_head *rhead) > > +{ > > + device_link_free(container_of(rhead, struct device_link, rcu_head)); > > +} > > + > > static void devlink_dev_release(struct device *dev) > > { > > - kfree(to_devlink(dev)); > > + struct device_link *link = to_devlink(dev); > > + > > + call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu); > > } > > +#else > > +static void devlink_dev_release(struct device *dev) > > +{ > > + device_link_free(to_devlink(dev)); > > +} > > +#endif > > > > static struct class devlink_class = { > > .name = "devlink", > > @@ -730,22 +754,7 @@ static void device_link_add_missing_supplier_links(void) > > mutex_unlock(&wfs_lock); > > } > > > > -static void device_link_free(struct device_link *link) > > -{ > > - while (refcount_dec_not_one(&link->rpm_active)) > > - pm_runtime_put(link->supplier); > > - > > - put_device(link->consumer); > > - put_device(link->supplier); > > - device_unregister(&link->link_dev); > > -} > > - > > #ifdef CONFIG_SRCU > > -static void __device_link_free_srcu(struct rcu_head *rhead) > > -{ > > - device_link_free(container_of(rhead, struct device_link, rcu_head)); > > -} > > - > > static void __device_link_del(struct kref *kref) > > { > > struct device_link *link = container_of(kref, struct device_link, kref); > > @@ -758,7 +767,7 @@ static void __device_link_del(struct kref *kref) > > > > list_del_rcu(&link->s_node); > > list_del_rcu(&link->c_node); > > - call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu); > > + device_unregister(&link->link_dev); > > } > > #else /* !CONFIG_SRCU */ > > static void __device_link_del(struct kref *kref) > > @@ -773,7 +782,7 @@ static void __device_link_del(struct kref *kref) > > > > list_del(&link->s_node); > > list_del(&link->c_node); > > - device_link_free(link); > > + device_unregister(&link->link_dev); > > } > > #endif /* !CONFIG_SRCU */ > > > > Best regards > -- > Marek Szyprowski, PhD > Samsung R&D Institute Poland >
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