linux-kernel - Re: [PATCH 18/34] mm: Update vma_iter_store() to use MAS_WARN

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Message-ID: <20230427011717.3vakguhb3lprg5cy@revolver>
Date:   Wed, 26 Apr 2023 21:17:17 -0400
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        maple-tree@...ts.infradead.org, Petr Mladek <pmladek@...e.com>
Subject: Re: [PATCH 18/34] mm: Update vma_iter_store() to use MAS_WARN_ON()

* Sergey Senozhatsky <senozhatsky@...omium.org> [230426 21:07]:
> Cc-ing Petr
> 
> On (23/04/25 10:09), Liam R. Howlett wrote:
> > +	if (MAS_WARN_ON(&vmi->mas, vmi->mas.node != MAS_START &&
> > +			vmi->mas.index > vma->vm_start)) {
> > +		printk("%lx > %lx\n", vmi->mas.index, vma->vm_start);
> > +		printk("store of vma %lx-%lx", vma->vm_start, vma->vm_end);
> > +		printk("into slot    %lx-%lx", vmi->mas.index, vmi->mas.last);
> >  	}
> 
> [..]
> 
> > +	if (MAS_WARN_ON(&vmi->mas, vmi->mas.node != MAS_START &&
> > +			vmi->mas.last <  vma->vm_start)) {
> > +		printk("%lx < %lx\n", vmi->mas.last, vma->vm_start);
> > +		printk("store of vma %lx-%lx", vma->vm_start, vma->vm_end);
> > +		printk("into slot    %lx-%lx", vmi->mas.index, vmi->mas.last);
> >  	}
> 
> Any reason for "store of vma" and "into slot" to be two separate
> printk()-s? It's not guaranteed that these will be printed as a
> continuous line. A single printk should work fine:
> 
> 	pr_foo("store of vma %lx-%lx into slot    %lx-%lx", ...);
> 

Really, just for readability.  I'll split the string literal instead.

> The line probably needs to be terminated with \n unless you expect
> more pr_cont() printks after this, which doesn't look like a case.
> Additionally, do you want to pass a specific loglevel? E.g. pr_debug()?

Yes, I should do both of these, thanks.