Messages in this thread | | | Subject | Re: [PATCH v2 2/3] kfence: maximize allocation wait timeout duration | From | Kefeng Wang <> | Date | Thu, 16 Sep 2021 09:02:27 +0800 |
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On 2021/4/21 18:51, Marco Elver wrote: > The allocation wait timeout was initially added because of warnings due > to CONFIG_DETECT_HUNG_TASK=y [1]. While the 1 sec timeout is sufficient > to resolve the warnings (given the hung task timeout must be 1 sec or > larger) it may cause unnecessary wake-ups if the system is idle. > [1] https://lkml.kernel.org/r/CADYN=9J0DQhizAGB0-jz4HOBBh+05kMBXb4c0cXMS7Qi5NAJiw@mail.gmail.com > > Fix it by computing the timeout duration in terms of the current > sysctl_hung_task_timeout_secs value. > > Signed-off-by: Marco Elver <elver@google.com> > --- > mm/kfence/core.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/mm/kfence/core.c b/mm/kfence/core.c > index 235d726f88bc..9742649f3f88 100644 > --- a/mm/kfence/core.c > +++ b/mm/kfence/core.c > @@ -20,6 +20,7 @@ > #include <linux/moduleparam.h> > #include <linux/random.h> > #include <linux/rcupdate.h> > +#include <linux/sched/sysctl.h> > #include <linux/seq_file.h> > #include <linux/slab.h> > #include <linux/spinlock.h> > @@ -621,7 +622,16 @@ static void toggle_allocation_gate(struct work_struct *work) > /* Enable static key, and await allocation to happen. */ > static_branch_enable(&kfence_allocation_key); > > - wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), HZ); > + if (sysctl_hung_task_timeout_secs) { > + /* > + * During low activity with no allocations we might wait a > + * while; let's avoid the hung task warning. > + */ > + wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), > + sysctl_hung_task_timeout_secs * HZ / 2); > + } else { > + wait_event(allocation_wait, atomic_read(&kfence_allocation_gate)); > + } > > /* Disable static key and reset timer. */ > static_branch_disable(&kfence_allocation_key);
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