linux-kernel - RE: [PATCH v4 00/34] Printbufs - new data structure for building strings

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Date:   Mon, 20 Jun 2022 08:00:50 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Matthew Wilcox' <willy@...radead.org>
CC:     'Kent Overstreet' <kent.overstreet@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "pmladek@...e.com" <pmladek@...e.com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "enozhatsky@...omium.org" <enozhatsky@...omium.org>,
        "linux@...musvillemoes.dk" <linux@...musvillemoes.dk>
Subject: RE: [PATCH v4 00/34] Printbufs - new data structure for building
 strings

From: Matthew Wilcox
> Sent: 20 June 2022 05:55
> 
> On Mon, Jun 20, 2022 at 04:19:31AM +0000, David Laight wrote:
> > I really think that is a bad idea.
> > printk() already uses a lot of stack, anything doing a recursive
> > call is just making that worse.
> > Especially since these calls can often be in error paths
> > which are not often tested and can already be on deep stacks.
> 
> You made this complaint last time and I challenged you to provide data.
> You have not, as yet, provided data.

There is already an issue with printk() needing 2k of stack and
'blowing' the stack in the stack overflow check.
This is with KASAN, but that that probably doesn't make
a massive difference - especially since it has more stack
to play with.

	David

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