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;a=summary
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@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Mar 9 14:20:51 PST 2018
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Date: Thu, 8 Mar 2018 16:17:36 +0100
Subject: bpf: add schedule points in percpu arrays management
To: gregkh@xxxxxxxxxxxxxxxxxxx
Cc: ast@xxxxxxxxxx, daniel@xxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx, Eric Dumazet <edumazet@xxxxxxxxxx>
Message-ID: <2f5704af2bdf05e8eae92917e2aeaec49d5477c9.1520521792.git.daniel@xxxxxxxxxxxxx>
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxx 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