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Date: Fri, 29 Mar 2024 23:52:31 +0800
From: Shung-Hsi Yu <shung-hsi.yu@suse.com>
To: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>, 
	Edward Adam Davis <eadavis@qq.com>, John Fastabend <john.fastabend@gmail.com>, 
	syzbot+c4f4d25859c2e5859988@syzkaller.appspotmail.com, 42.hyeyoo@gmail.com, andrii@kernel.org, ast@kernel.org, 
	bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net, edumazet@google.com, 
	kafai@fb.com, kpsingh@kernel.org, kuba@kernel.org, 
	linux-kernel@vger.kernel.org, namhyung@kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, 
	peterz@infradead.org, songliubraving@fb.com, syzkaller-bugs@googlegroups.com, 
	yhs@fb.com, Xin Liu <liuxin350@huawei.com>
Subject: Re: [PATCH] bpf, sockmap: fix deadlock in rcu_report_exp_cpu_mult
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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@mail.gmail.com/

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@mail.gmail.com/