linux-kernel - Re: commit dd4cf8c9e1f4 leads to failed boot

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Message-ID: <82ff38fc-b295-472c-bde5-bd96f0d144fb@paulmck-laptop>
Date: Wed, 23 Apr 2025 11:07:45 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: "Aithal, Srikanth" <sraithal@....com>
Cc: Bert Karwatzki <spasswolf@....de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kuniyuki Iwashima <kuniyu@...zon.com>,
	Mateusz Guzik <mjguzik@...il.com>, Petr Mladek <pmladek@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	linux-kernel@...r.kernel.org,
	Linux-Next Mailing List <linux-next@...r.kernel.org>
Subject: Re: commit dd4cf8c9e1f4 leads to failed boot

On Wed, Apr 23, 2025 at 08:49:08PM +0530, Aithal, Srikanth wrote:
> On 4/23/2025 7:48 PM, Paul E. McKenney wrote:
> > On Wed, Apr 23, 2025 at 07:09:42PM +0530, Aithal, Srikanth wrote:
> > > On 4/23/2025 5:24 PM, Bert Karwatzki wrote:
> > > > Since linux next-20250422 booting fails on my MSI Alpha 15 Laptop runnning
> > > > debian sid. When booting kernel message appear on screen but no messages from
> > > > init (systemd). There are also no logs written even thought emergency sync
> > > > via magic sysrq works (a message is printed on screen), presumably because
> > > > / is not mounted. I bisected this (from 6.15-rc3 to next-20250422) and found
> > > > commit dd4cf8c9e1f4 as the first bad commit.
> > > > Reverting commit dd4cf8c9e1f4 in next-20250422 fixes the issue.
> > > 
> > > 
> > > Hello,
> > > 
> > > On AMD platform as well boot failed starting next-20250422, bisecting the
> > > issue led me to same commit dd4cf8c9e1f4. I have attached kernel config and
> > > logs.
> > 
> > Thank you all for the bisection and the report!
> > 
> > Please check out the predecessor of commit dd4cf8c9e1f4 ("ratelimit:
> > Force re-initialization when rate-limiting re-enabled"):
> > 
> > 13fa70e052dd ("ratelimit: Allow zero ->burst to disable ratelimiting")
> > 
> > Then please apply the patch shown below, and let me know what happens?
> > (Yes, I should have split that commit up...)
> > 
> > 							Thanx, Paul
> > 
> > ------------------------------------------------------------------------
> > 
> > diff --git a/lib/ratelimit.c b/lib/ratelimit.c
> > index 04f16b8e24575..13ed636642270 100644
> > --- a/lib/ratelimit.c
> > +++ b/lib/ratelimit.c
> > @@ -35,7 +35,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
> >   	unsigned long flags;
> >   	int ret;
> > -	if (!interval || !burst)
> > +	if (interval <= 0 || burst <= 0)
> >   		return 1;
> >   	/*
> 
> 
> I applied above patch on top of 13fa70e052dd ("ratelimit: Allow zero ->burst
> to disable ratelimiting") [linux-20250423]. This is fixing the boot issue.
> 
> Tested-by: Srikanth Aithal <sraithal@....com>

Thank you both, and to Bert for intuiting the correct -next commit!

Could you please try the next increment, which is this patch, again
on top of 24ff89c63355 ("ratelimit: Allow zero ->burst to > disable
ratelimiting")?

In the meantime, I will expose the version you two just tested to
-next.

							Thanx, Paul

------------------------------------------------------------------------

diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index 04f16b8e24575..8f6c54f719ef2 100644
--- a/lib/ratelimit.c
+++ b/lib/ratelimit.c
@@ -35,8 +35,10 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
 	unsigned long flags;
 	int ret;
 
-	if (!interval || !burst)
+	if (interval <= 0 || burst <= 0) {
+		ret = burst > 0;
 		return 1;
+	}
 
 	/*
 	 * If we contend on this state's lock then just check if