linux-kernel - Re: [GIT PULL] probes: Fixes for v6.12-rc4-2

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Message-ID: <CAHk-=whO+vSH+XVRio8byJU8idAWES0SPGVZ7KAVdc4qrV0VUA@mail.gmail.com>
Date: Thu, 24 Oct 2024 14:05:08 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Leo Yan <leo.yan@....com>, Mikel Rychliski <mikel@...elr.com>, Viktor Malik <vmalik@...hat.com>, 
	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] probes: Fixes for v6.12-rc4-2

On Wed, 23 Oct 2024 at 07:36, Masami Hiramatsu <mhiramat@...nel.org> wrote:
>
> - objpool: Fix choosing allocation for percpu slots
>
>   Fixes to allocate objpool's percpu slots correctly according to the
>   GFP flag. It checks whether "any bit" in GFP_ATOMIC is set to choose
>   the vmalloc source, but it should check "all bits" in GFP_ATOMIC flag
>   is set, because GFP_ATOMIC is a combined flag.

So the old code was buggy, but I don't think the new code is wonderful either.

For example, it does not recognized GFP_NOWAIT, which has very similar
characteristics to GFP_ATOMIC (it's basically the same thing as
GFP_ATOMIC, but without the "try to allocate urgently", and with an
added "don't warn on failure" as a result).

So what I think that code *should* test for is "can I sleep".

Which is indicated by __GFP_IO or __GFP_FS (and, I guess also
__GFP_DIRECT_RECLAIM).

                Linus