Re: IPF Montvale machine panic when running a network-releventtesting

[David Miller]

From: "Zhang, Yanmin" <yanmin_zhang@xxxxxxxxxxxxxxx>
Date: Wed, 18 Jun 2008 11:27:43 +0800

> This issue is caused by tcp defer accept. Mostly, process context calls lock_sock
> to apply a sleeping lock. BH (SoftIRQ) context calls bh_lock_sock(_nested) to just apply
> for the sk->sk_lock.slock without sleeping, then do appropriate processing based on
> if sk->sk_lock.owned==0. That works well if both process context and BH context operate
> the same sk at the same time. But with ïtcp defer accept, it doesn't, because
> process context(for example, in inet_csk_accept) locks the listen sk, while BH
> context (in tcp_v4_rcv, for example) locks the child sk and calls
> ïtcp_defer_accept_checkï => inet_csk_reqsk_queue_add => reqsk_queue_add, so there is a race
> to access the listen sock.
> 
> Below patch against 2.6.26-rc6 fixes the issue.
> 
> ïïSigned-off-by: Zhang Yanmin <yanmin.zhang@xxxxxxxxx>

We reverted the guilty defer accept changes, please test Linus's
current tree.
N‹§²æìr¸›yúèšØb²X¬¶ÇvØ^–)Þ{.nÇ+‰·¥Š{±‘êçzX§¶›¡Ü}©ž²ÆzÚ&j:+v‰¨¾«‘êçzZ+€Ê+zf£¢·hšˆ§~†­†Ûiÿûàz¹®w¥¢¸?™¨è­Ú&¢)ßf”ù^jÇy§m…á@A«a¶Úÿ0¶ìh®å’i