This is a note to let you know that I've just added the patch titled
bpf: add schedule points in percpu arrays management
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: bpf-add-schedule-points-in-percpu-arrays-management.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Fri Mar 9 14:20:51 PST 2018
From: Daniel Borkmann daniel@iogearbox.net Date: Thu, 8 Mar 2018 16:17:36 +0100 Subject: bpf: add schedule points in percpu arrays management To: gregkh@linuxfoundation.org Cc: ast@kernel.org, daniel@iogearbox.net, stable@vger.kernel.org, Eric Dumazet edumazet@google.com Message-ID: 2f5704af2bdf05e8eae92917e2aeaec49d5477c9.1520521792.git.daniel@iogearbox.net
From: Eric Dumazet edumazet@google.com
[ upstream commit 32fff239de37ef226d5b66329dd133f64d63b22d ]
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 Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/arraymap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -20,8 +20,10 @@ static void bpf_array_free_percpu(struct { 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) @@ -37,6 +39,7 @@ static int bpf_array_alloc_percpu(struct return -ENOMEM; } array->pptrs[i] = ptr; + cond_resched(); }
return 0;
Patches currently in stable-queue which might be from daniel@iogearbox.net are
queue-4.9/bpf-fix-mlock-precharge-on-arraymaps.patch queue-4.9/bpf-x64-implement-retpoline-for-tail-call.patch queue-4.9/bpf-arm64-fix-out-of-bounds-access-in-tail-call.patch queue-4.9/bpf-fix-wrong-exposure-of-map_flags-into-fdinfo-for-lpm.patch queue-4.9/bpf-ppc64-fix-out-of-bounds-access-in-tail-call.patch queue-4.9/bpf-add-schedule-points-in-percpu-arrays-management.patch