[LU-19528] LNet: restore kernel callback before freeing listener socket

• Type: Bug
• Resolution: Unresolved
• Priority: Medium
• Labels: lnet
• Severity: 3
• Assignee: Serguei Smirnov
• Reporter: Serguei Smirnov

Description

If callback is not restored before the socket is freed,  it can be released while its sk_data_ready still points at lnet_acceptor_ready. A late interrupt can then occur during the teardown and cause a crash similar to the following: 

[13332.813987] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[13332.815268] PGD 0 P4D 0
[13332.815730] Oops: 0000 [#1] SMP PTI
[13332.816323] CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: G OE -------- - - 4.18.0-553.51.1.el8_10.x86_64 #1
[13332.818144] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [13332.819071] RIP: 0010:__wake_up_common+0x4c/0x190