linux-kernel - Re: [PATCH] mm: ratelimit oversized kvmalloc warnings instead of once

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Date: Wed, 19 Jun 2024 21:54:48 +0200
From: Michal Hocko <mhocko@...e.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Shakeel Butt <shakeel.butt@...ux.dev>,
	Andrew Morton <akpm@...ux-foundation.org>, kernel-team@...a.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Kyle McMartin <kyle@...radead.org>
Subject: Re: [PATCH] mm: ratelimit oversized kvmalloc warnings instead of once

On Wed 19-06-24 12:30:42, Linus Torvalds wrote:
> On Wed, 19 Jun 2024 at 10:47, Shakeel Butt <shakeel.butt@...ux.dev> wrote:
> >
> > Linus, please let me know if you have any concerns on the approach
> > Michal is suggesting i.e. a variant for warn once for unique call stack.
> 
> I think we should just try to change the existing WARN_ONCE(), and see
> if it causes any issues.
> 
> A new "WARN_UNIQUE()" might be the borign and safe approach, but
> 
>  (a) it won't actually be unique if you don't have stackdepot anyway,
> and will just be WARN_ONCE
> 
>  (b) I suspect most WARN_ONCE users really do want WARN_UNIQUE
> 
> so let's at least _start_ with just changing semantics of the existing
> "once", and then if it causes problems we'll have to revisit this.
> 
> I doubt it will cause problems,

I would be careful about the WARN_ONCE used from stackdepot itself. It's
been some time since I have looked into that code but a quick grep tells
there is some usage.

-- 
Michal Hocko
SUSE Labs