Patch "bpf: add schedule points in percpu arrays management" has been added to the 4.14-stable tree

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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 4.14-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-4.14 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 14:18:36 PST 2018
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Date: Thu,  8 Mar 2018 13:14:45 +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: <498449c87b8c123b6ab6ffe2882a9b108473e256.1520504748.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
@@ -23,8 +23,10 @@ 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)
@@ -40,6 +42,7 @@ 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-4.14/bpf-fix-mlock-precharge-on-arraymaps.patch
queue-4.14/bpf-x64-implement-retpoline-for-tail-call.patch
queue-4.14/bpf-arm64-fix-out-of-bounds-access-in-tail-call.patch
queue-4.14/bpf-fix-memory-leak-in-lpm_trie-map_free-callback-function.patch
queue-4.14/bpf-ppc64-fix-out-of-bounds-access-in-tail-call.patch
queue-4.14/bpf-add-schedule-points-in-percpu-arrays-management.patch
queue-4.14/bpf-allow-xadd-only-on-aligned-memory.patch
queue-4.14/bpf-fix-rcu-lockdep-warning-for-lpm_trie-map_free-callback.patch



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