Re: Kernel panic: Route cache, RCU, possibly FIB trie.

Dipankar Sarma a écrit :

On Tue, Mar 21, 2006 at 04:37:19PM +0100, Eric Dumazet wrote:

Jesper Dangaard Brouer a écrit :

There is definitly high memory pressure on this machine!

Slab memory usage, range from 39Mb to 205Mb (at the moment on the production servers).

Did you tried 2.6.16 ?

It contains changes in kernel/rcupdate.c so that not too many RCU elems are queued (force_quiescent_state()). So in the case a rt_cache_flush is done, you have the guarantee all entries are not pushed into rcu at once.

Well, memory pressure or not, the oopses shouldn't be happening :)
Perhaps we should look at them before we work around memory
pressure through the rcu batch tuning stuff in 2.6.16 ?

One of the oopses looked like the rcu callback function pointer getting corrupted indicating that it was double freed or

problem with RCU itself.

Yep, but as this is a production server, I believe its owner might want a fast way to have it back to life :)

And the RCU change in 2.6.16 is definitly a big improvement when a dump of million entries is done :)

If RCU quiescent state is forced, maybe the bug (in the route cache code) will trigger faster ?

Eric
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---

• References:
  • Kernel panic: Route cache, RCU, possibly FIB trie.
    • From: Jesper Dangaard Brouer <[email protected]>
  • Kernel panic: Route cache, RCU, possibly FIB trie.
    • From: Robert Olsson <[email protected]>
  • Re: Kernel panic: Route cache, RCU, possibly FIB trie.
    • From: Jesper Dangaard Brouer <[email protected]>
  • Re: Kernel panic: Route cache, RCU, possibly FIB trie.
    • From: Eric Dumazet <[email protected]>
  • Re: Kernel panic: Route cache, RCU, possibly FIB trie.
    • From: Dipankar Sarma <[email protected]>

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