From: Matthew Wilcox <willy@infradead.org>
To: Leon Romanovsky <leon@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Bixuan Cui <cuibixuan@linux.alibaba.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, w@1wt.eu, keescook@chromium.org
Subject: Re: [PATCH -next] mm: delete oversized WARN_ON() in kvmalloc() calls
Date: Thu, 2 Dec 2021 15:29:47 +0000 [thread overview]
Message-ID: <YajmawzehKqR+j0v@casper.infradead.org> (raw)
In-Reply-To: <Yajk/oVypyUFTtgd@unreal>
On Thu, Dec 02, 2021 at 05:23:42PM +0200, Leon Romanovsky wrote:
> The problem is that this WARN_ON() is triggered by the users.
... or the problem is that you don't do a sanity check between the user
and the MM system. I mean, that's what this conversation is about --
is it a bug to be asking for this much memory in the first place?
> At least in the RDMA world, users can provide huge sizes and they expect
> to get plain -ENOMEM and not dump stack, because it happens indirectly
> to them.
>
> In our case, these two kvcalloc() generates WARN_ON().
>
> umem_odp->pfn_list = kvcalloc(
> npfns, sizeof(*umem_odp->pfn_list), GFP_KERNEL);
Does it really make sense for the user to specify 2^31 PFNs in a single
call? I mean, that's 8TB of memory. Should RDMA put its own limit
in here, or should it rely on kvmalloc returning -ENOMEM?
next prev parent reply other threads:[~2021-12-02 15:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-02 2:06 Bixuan Cui
2021-12-02 2:53 ` Tang Yizhou
2021-12-02 3:26 ` Andrew Morton
2021-12-02 4:05 ` Bixuan Cui
2021-12-02 4:29 ` Andrew Morton
2021-12-02 10:38 ` Jeremy Sowden
2021-12-02 15:34 ` Alexei Starovoitov
2021-12-02 21:16 ` Jeremy Sowden
2021-12-02 11:49 ` Bixuan Cui
2021-12-03 19:37 ` Sean Christopherson
2021-12-02 15:23 ` Leon Romanovsky
2021-12-02 15:29 ` Matthew Wilcox [this message]
2021-12-02 16:08 ` Leon Romanovsky
2021-12-02 19:08 ` Kees Cook
2021-12-02 19:24 ` Leon Romanovsky
2021-12-02 21:23 ` Kees Cook
2021-12-02 22:03 ` Andrew Morton
2021-12-03 4:39 ` Matthew Wilcox
2021-12-02 17:00 ` Jason Gunthorpe
2021-12-02 3:46 ` Kees Cook
2021-12-02 4:44 ` Bixuan Cui
2021-12-02 17:03 ` Jason Gunthorpe
2021-12-05 11:59 ` Leon Romanovsky
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=YajmawzehKqR+j0v@casper.infradead.org \
--to=willy@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=cuibixuan@linux.alibaba.com \
--cc=keescook@chromium.org \
--cc=leon@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=torvalds@linux-foundation.org \
--cc=w@1wt.eu \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox