From: "Harry Yoo (Oracle)" <harry@kernel.org>
To: "Denis M. Karpov" <komlomal@gmail.com>
Cc: rppt@kernel.org, akpm@linux-foundation.org,
Liam.Howlett@oracle.com, ljs@kernel.org, vbabka@kernel.org,
jannh@google.com, peterx@redhat.com, pfalcato@suse.de,
brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, usama.arif@linux.dev
Subject: Re: [PATCH v2] userfaultfd: allow registration of ranges below mmap_min_addr
Date: Thu, 9 Apr 2026 20:56:49 +0900 [thread overview]
Message-ID: <adeUASM9tEzo1Tnx@hyeyoo> (raw)
In-Reply-To: <20260409103345.15044-1-komlomal@gmail.com>
On Thu, Apr 09, 2026 at 01:33:45PM +0300, Denis M. Karpov wrote:
> The current implementation of validate_range() in fs/userfaultfd.c
> performs a hard check against mmap_min_addr. This is redundant because
> UFFDIO_REGISTER operates on memory ranges that must already be backed
> by a VMA.
>
> Enforcing mmap_min_addr or capability checks again in userfaultfd is
> unnecessary and prevents applications like binary compilers from
> using UFFD for valid memory regions mapped by application.
>
> Remove the redundant check for mmap_min_addr.
>
> Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization")
> Signed-off-by: Denis M. Karpov <komlomal@gmail.com>
> ---
> v2:
> - Remove the check entirely rather than replacing it, as suggested by
> Harry Yoo and Lorenzo Stoakes.
> - Added Fixes tag.
> - Link to v1: https://lore.kernel.org/r/20260407081442.6256-1-komlomal@gmail.com
> ---
Looks good to me,
Acked-by: Harry Yoo (Oracle) <harry@kernel.org>
--
Cheers,
Harry / Hyeonggon
next prev parent reply other threads:[~2026-04-09 11:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-09 10:33 Denis M. Karpov
2026-04-09 10:43 ` Lorenzo Stoakes
2026-04-09 11:56 ` Harry Yoo (Oracle) [this message]
2026-04-09 12:30 ` Pedro Falcato
2026-04-09 15:17 ` Mike Rapoport
2026-04-09 15:54 ` Denis M. Karpov
2026-04-09 15:13 ` Mike Rapoport
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=adeUASM9tEzo1Tnx@hyeyoo \
--to=harry@kernel.org \
--cc=Liam.Howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=brauner@kernel.org \
--cc=jack@suse.cz \
--cc=jannh@google.com \
--cc=komlomal@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=ljs@kernel.org \
--cc=peterx@redhat.com \
--cc=pfalcato@suse.de \
--cc=rppt@kernel.org \
--cc=usama.arif@linux.dev \
--cc=vbabka@kernel.org \
--cc=viro@zeniv.linux.org.uk \
/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