All of lore.kernel.org
 help / color / mirror / Atom feed
From: Andrea Righi <andrea.righi@canonical.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	linux-modules@vger.kernel.org, patches@lists.linux.dev,
	linux-kernel@vger.kernel.org, keescook@chromium.org,
	zhumao001@208suo.com, yangtiezhu@loongson.cn, ojeda@kernel.org
Subject: Re: [GIT PULL] Modules changes for v6.7-rc1
Date: Thu, 2 Nov 2023 08:22:53 +0100	[thread overview]
Message-ID: <ZUNOTRWCWNJkn66n@gpd> (raw)
In-Reply-To: <CAHk-=whFXNYXG2ES8HdoaMC=O4bakMXGZezmoqA3SXwn4xJUPQ@mail.gmail.com>

On Wed, Nov 01, 2023 at 09:02:51PM -1000, Linus Torvalds wrote:
> On Wed, 1 Nov 2023 at 10:13, Luis Chamberlain <mcgrof@kernel.org> wrote:
> >
> > The only thing worth highligthing is that gzip moves to use vmalloc() instead of
> > kmalloc just as we had a fix for this for zstd on v6.6-rc1.
> 
> Actually, that's almost certainly entirely the wrong thing to do.
> 
> Unless you *know* that the allocation is large, you shouldn't use
> vmalloc(). And since kmalloc() has worked fine, you most definitely
> don't know that.
> 
> So we have 'kvmalloc()' *exactly* for this reason, which is a "use
> kmalloc, unless that is too small, then use vmalloc".
> 
> kmalloc() isn't just about "use physically contiguous allocations".
> It's also more memory-efficient, and a *lot* faster than vmalloc(),
> which has to play VM tricks.
> 
> So this "just switch to vmalloc()" is entirely wrong.
> 
>               Linus

I proposed that change mostlfy for consistency with the zstd case, but I
haven't experience any issue with gzip compressed modules (that seem to
require less memory, even with larger modules).

So, yes, it probably makes sense to drop this change for now and I can
send another patch to switch to kvmalloc() for all the decompress cases.

Thanks,
-Andrea

  parent reply	other threads:[~2023-11-02  7:30 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-01 20:13 [GIT PULL] Modules changes for v6.7-rc1 Luis Chamberlain
2023-11-02  7:02 ` Linus Torvalds
2023-11-02  7:21   ` Linus Torvalds
2023-11-02  7:29     ` Andrea Righi
2023-11-02  8:19       ` Andrea Righi
2023-11-02  7:22   ` Andrea Righi [this message]
2023-11-02  7:23 ` pr-tracker-bot

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=ZUNOTRWCWNJkn66n@gpd \
    --to=andrea.righi@canonical.com \
    --cc=keescook@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-modules@vger.kernel.org \
    --cc=mcgrof@kernel.org \
    --cc=ojeda@kernel.org \
    --cc=patches@lists.linux.dev \
    --cc=torvalds@linux-foundation.org \
    --cc=yangtiezhu@loongson.cn \
    --cc=zhumao001@208suo.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.