Re: [PATCH] bpf, sockmap: fix deadlock in rcu_report_exp_cpu_mult

[Shung-Hsi Yu]

On Tue, Mar 26, 2024 at 11:15:47PM +0100, Jakub Sitnicki wrote:
> On Mon, Mar 25, 2024 at 01:23 PM +01, Jakub Sitnicki wrote:
> > On Sat, Mar 23, 2024 at 12:08 AM -07, Alexei Starovoitov wrote:
> >> It seems this bug was causing multiple syzbot reports.
> > Any chance we could disallow mutating sockhash from interrupt context?
> 
> I've been playing with the repro from one of the other reports:
> 
> https://lore.kernel.org/all/CABOYnLzaRiZ+M1v7dPaeObnj_=S4JYmWbgrXaYsyBbWh=553vQ@xxxxxxxxxxxxxx/

Possibly also related:
- "A potential deadlock in sockhash map"[1] report awhile back
- commit ed17aa92dc56b ("bpf, sockmap: fix deadlocks in the sockhash and
  sockmap")
- commit 8c5c2a4898e3d ("bpf, sockmap: Revert buggy deadlock fix in the
  sockhash and sockmap")

1: https://lore.kernel.org/all/CABcoxUayum5oOqFMMqAeWuS8+EzojquSOSyDA3J_2omY=2EeAg@xxxxxxxxxxxxxx/