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Message-ID: <48797a0c929e87a72fccc48ce5cb95263da23e22.camel@perches.com>
Subject: Re: [RFC[ Alloc in vsprintf
From:   Joe Perches <joe@perches.com>
To:     Kent Overstreet <kent.overstreet@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        David Laight <David.Laight@ACULAB.COM>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Matthew Wilcox <willy@infradead.org>,
        Miguel Ojeda <ojeda@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>
Date:   Sun, 26 Jun 2022 13:13:18 -0700
In-Reply-To: <20220626200618.jhxu5lg4w7o2irhr@moria.home.lan>
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On Sun, 2022-06-26 at 16:06 -0400, Kent Overstreet wrote:
> On Sun, Jun 26, 2022 at 12:53:26PM -0700, Joe Perches wrote:
> > In a reply to the printbufs thread, I wrote a proposal to use an
> > alloc to reduce stack in vsprintf when CONFIG_KALLSYMS is enabled.
> > 
> > No one has replied to this but I think it's somewhat sensible.
> > 
> > Thoughts?
> 
> As functions get converted to printbufs the separate stack allocated buffers
> become unnecessary, because printbufs have helpers that do bounds checking and
> make outputting to the vsprintf buffer painless. So it's not necessary - I
> haven't fully converted symbol_string() yet but I'll do so by the time I mail
> out the next round of patches.

_If_ the printfbufs patch series gets applied.
I think that series is not great yet.

Even if applied via something like the printbufs series, the
stack use of this function needs/could use attending.

~700 bytes of stack use here isn't great.