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

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Message-ID: <395d9ed9cf1ab427f6b71645f4c732737981c547.camel@web.de>
Date: Wed, 23 Apr 2025 20:03:58 +0200
From: Bert Karwatzki <spasswolf@....de>
To: paulmck@...nel.org, "Aithal, Srikanth" <sraithal@....com>
Cc: 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>, spasswolf@....de
Subject: Re: commit dd4cf8c9e1f4 leads to failed boot

Am Mittwoch, dem 23.04.2025 um 16:59 +0200 schrieb Bert Karwatzki:
> Am Mittwoch, dem 23.04.2025 um 07:18 -0700 schrieb Paul E. McKenney:
> > 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")
> 
> The predecessor commit is 24ff89c63355 ("ratelimit: Allow zero ->burst to
> disable ratelimiting") in linux-next.
> 
> > 
> > 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;
> >  
> >  	/*
> 
> The patch applied on top of 24ff89c63355 ("ratelimit: Allow zero ->burst to
> disable ratelimiting") works fine.
> 
> Bert Karwatzki

The problem seems to be the burst == 0 case, this patch fixes the issue in
next-20250422:

diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index b5c727e976d2..cb7810655027 100644
--- a/lib/ratelimit.c
+++ b/lib/ratelimit.c
@@ -40,7 +40,8 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
         * interval says never limit.
         */
        if (interval <= 0 || burst <= 0) {
-               ret = burst > 0;
+               //ret = burst > 0;
+               ret = 1;
                if (!(READ_ONCE(rs->flags) & RATELIMIT_INITIALIZED) ||
                    !raw_spin_trylock_irqsave(&rs->lock, flags))
                        return ret;


Bert Karwatzki