This is a note to let you know that I've just added the patch titled
af_unix: limit unix_tot_inflight
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
af_unix-limit-unix_tot_inflight.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From 41089d9daf565832cb31b6deb237daaab77f28ab Mon Sep 17 00:00:00 2001
From: Eric Dumazet <[email protected]>
Date: Wed, 24 Nov 2010 09:15:27 -0800
Subject: af_unix: limit unix_tot_inflight
From: Eric Dumazet <[email protected]>
commit 9915672d41273f5b77f1b3c29b391ffb7732b84b upstream.
Vegard Nossum found a unix socket OOM was possible, posting an exploit
program.
My analysis is we can eat all LOWMEM memory before unix_gc() being
called from unix_release_sock(). Moreover, the thread blocked in
unix_gc() can consume huge amount of time to perform cleanup because of
huge working set.
One way to handle this is to have a sensible limit on unix_tot_inflight,
tested from wait_for_unix_gc() and to force a call to unix_gc() if this
limit is hit.
This solves the OOM and also reduce overall latencies, and should not
slowdown normal workloads.
Reported-by: Vegard Nossum <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/unix/garbage.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -269,9 +269,16 @@ static void inc_inflight_move_tail(struc
}
static bool gc_in_progress = false;
+#define UNIX_INFLIGHT_TRIGGER_GC 16000
void wait_for_unix_gc(void)
{
+ /*
+ * If number of inflight sockets is insane,
+ * force a garbage collect right now.
+ */
+ if (unix_tot_inflight > UNIX_INFLIGHT_TRIGGER_GC && !gc_in_progress)
+ unix_gc();
wait_event(unix_gc_wait, gc_in_progress == false);
}
Patches currently in longterm-queue-2.6.32 which might be from
[email protected] are
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/af_unix-limit-unix_tot_inflight.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/af_unix-limit-recursion-level.patch
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