Re: [nacked] mm-oom-avoid-printk-iteration-under-rcu.patch removed from -mm tree

[Sergey Senozhatsky <sergey.senozhatsky@gmail.com>]

On (20/04/23 22:28), Tetsuo Handa wrote:
[..]
> +/* Annotation for "don't print to consoles". */
> +#define KERN_NO_CONSOLES KERN_SOH "S"
> +
>  /* integer equivalents of KERN_<LEVEL> */
>  #define LOGLEVEL_SCHED		-2	/* Deferred messages from sched code
>  					 * are set to this special level */
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> index e061635e0409..da338b81c2e1 100644
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -19,6 +19,7 @@ static inline int printk_get_level(const char *buffer)
>  		switch (buffer[1]) {
>  		case '0' ... '7':
>  		case 'c':	/* KERN_CONT */
> +		case 'S':       /* KERN_NO_CONSOLES */
>  			return buffer[1];
>  		}
>  	}
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 9a9b6156270b..ed51641af087 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -361,6 +361,7 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
>   */
>  
>  enum log_flags {
> +	LOG_NO_CONSOLES = 1,    /* don't print to consoles */
>  	LOG_NEWLINE	= 2,	/* text ended with a newline */
>  	LOG_CONT	= 8,	/* text is a fragment of a continuation line */
>  };
> @@ -1959,6 +1960,9 @@ int vprintk_store(int facility, int level,
>  				break;
>  			case 'c':	/* KERN_CONT */
>  				lflags |= LOG_CONT;
> +				break;
> +			case 'S':       /* KERN_NO_CONSOLES */
> +				lflags |= LOG_NO_CONSOLES;
>  			}
[..]

Hmm. Any chance that those NO_CONSOLE messages overflow logbuf so then
we start losing pending YES_CONSOLE messages?

	-ss