| Message ID | 1519317204.55655.55.camel@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: add schedule points in percpu arrays management | expand |
[ +Dennis for mm/pcpu ] On 02/22/2018 05:33 PM, Eric Dumazet wrote: > From: Eric Dumazet <edumazet@google.com> > > syszbot managed to trigger RCU detected stalls in > bpf_array_free_percpu() > > It takes time to allocate a huge percpu map, but even more time to free > it. > > Since we run in process context, use cond_resched() to yield cpu if > needed. > > Fixes: a10423b87a7e ("bpf: introduce BPF_MAP_TYPE_PERCPU_ARRAY map") > Signed-off-by: Eric Dumazet <edumazet@google.com> > Reported-by: syzbot <syzkaller@googlegroups.com> Applied to bpf tree, thanks Eric! > --- > kernel/bpf/arraymap.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c > index a364c408f25a54a8175c92b6004a5e7e15f198cb..14750e7c5ee4872e4a7426e960bea7ae001e6623 100644 > --- a/kernel/bpf/arraymap.c > +++ b/kernel/bpf/arraymap.c > @@ -26,8 +26,10 @@ static void bpf_array_free_percpu(struct bpf_array *array) > { > int i; > > - for (i = 0; i < array->map.max_entries; i++) > + for (i = 0; i < array->map.max_entries; i++) { > free_percpu(array->pptrs[i]); > + cond_resched(); > + } > } > > static int bpf_array_alloc_percpu(struct bpf_array *array) > @@ -43,6 +45,7 @@ static int bpf_array_alloc_percpu(struct bpf_array *array) > return -ENOMEM; > } > array->pptrs[i] = ptr; > + cond_resched(); > } > > return 0; >
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index a364c408f25a54a8175c92b6004a5e7e15f198cb..14750e7c5ee4872e4a7426e960bea7ae001e6623 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -26,8 +26,10 @@ static void bpf_array_free_percpu(struct bpf_array *array) { int i; - for (i = 0; i < array->map.max_entries; i++) + for (i = 0; i < array->map.max_entries; i++) { free_percpu(array->pptrs[i]); + cond_resched(); + } } static int bpf_array_alloc_percpu(struct bpf_array *array) @@ -43,6 +45,7 @@ static int bpf_array_alloc_percpu(struct bpf_array *array) return -ENOMEM; } array->pptrs[i] = ptr; + cond_resched(); } return 0;