From: Linus Torvalds <torvalds@linux-foundation.org>
To: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Android Kernel Team <kernel-team@android.com>,
Jan Kara <jack@suse.cz>, Linux-MM <linux-mm@kvack.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Minchan Kim <minchan@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Damian Tometzki <linux@tometzki.de>,
Vinayak Menon <vinmenon@codeaurora.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Will Deacon <will@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting
Date: Sun, 27 Dec 2020 15:40:36 -0800 [thread overview]
Message-ID: <CAHk-=wjvHxQDet0=DTkqmYni_fgDsG=2_-idECFxnd+ECKdg_g@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=whykpz1RfBZ8Cqk=80_d6BWsppGYBJXoWuWB9n+uUKxVA@mail.gmail.com>
On Sun, Dec 27, 2020 at 3:12 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Ok, your fix for that folded in, and here's yet another version.
Still not good.
I don't know what happened, but the change of
- vm_fault_t ret = 0;
+ vm_fault_t ret;
is very very wrong. The next user is
+ if (!(vma->vm_flags & VM_SHARED))
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ return ret;
so now 'ret' will potentially be used uninitialized (although this is
the kind of thing that a compiler might almost accidentally end up
fixing - with a single dominating assignment, I could imagine the
compiler moving the test to that assignment and thus "fixing" the code
without really even meaning to).
I think Kirill was intending to move the "if (ret)" up into the path
that sets it, IOW something like
+ if (!(vma->vm_flags & VM_SHARED)) {
+ ret = check_stable_address_space(vma->vm_mm);
+ if (ret)
+ return ret;
+ }
instead. But that patch as-is is broken.
Kirill?
Linus
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-12-27 23:43 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 16:39 [PATCH 0/2] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2020-12-09 16:39 ` [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Will Deacon
2020-12-09 17:58 ` Linus Torvalds
2020-12-09 18:40 ` Will Deacon
2020-12-09 19:04 ` Linus Torvalds
2020-12-09 20:32 ` Matthew Wilcox
2020-12-09 21:04 ` Linus Torvalds
2020-12-10 15:08 ` Kirill A. Shutemov
2020-12-10 17:23 ` Linus Torvalds
2020-12-14 16:07 ` Kirill A. Shutemov
2020-12-14 17:54 ` Linus Torvalds
2020-12-14 18:56 ` Matthew Wilcox
2020-12-16 17:07 ` Kirill A. Shutemov
2020-12-16 18:41 ` Linus Torvalds
2020-12-17 10:54 ` Kirill A. Shutemov
2020-12-17 18:22 ` Linus Torvalds
2020-12-18 11:04 ` Kirill A. Shutemov
2020-12-18 18:56 ` Linus Torvalds
2020-12-19 12:41 ` Kirill A. Shutemov
2020-12-19 20:08 ` Linus Torvalds
2020-12-19 20:34 ` Linus Torvalds
2020-12-22 10:00 ` Kirill A. Shutemov
2020-12-24 4:04 ` Hugh Dickins
2020-12-25 11:31 ` Kirill A. Shutemov
2020-12-26 17:57 ` Linus Torvalds
2020-12-26 20:43 ` Kirill A. Shutemov
2020-12-26 21:03 ` Hugh Dickins
2020-12-26 21:16 ` Linus Torvalds
2020-12-26 22:40 ` Kirill A. Shutemov
2020-12-27 0:45 ` Hugh Dickins
2020-12-27 2:38 ` Hugh Dickins
2020-12-27 19:38 ` Linus Torvalds
2020-12-27 20:32 ` Damian Tometzki
2020-12-27 22:35 ` Hugh Dickins
2020-12-27 23:12 ` Linus Torvalds
2020-12-27 23:40 ` Linus Torvalds [this message]
2020-12-27 23:55 ` Kirill A. Shutemov
2020-12-27 23:48 ` Kirill A. Shutemov
2020-12-28 1:54 ` Linus Torvalds
2020-12-28 6:43 ` Hugh Dickins
2020-12-28 12:53 ` Kirill A. Shutemov
2020-12-28 18:47 ` Linus Torvalds
2020-12-28 21:58 ` Linus Torvalds
2020-12-29 13:28 ` Kirill A. Shutemov
2020-12-29 15:19 ` Matthew Wilcox
2020-12-29 20:52 ` Linus Torvalds
2020-12-28 22:05 ` Kirill A. Shutemov
2020-12-28 22:12 ` Kirill A. Shutemov
2020-12-29 4:35 ` Hugh Dickins
2020-12-28 23:28 ` Linus Torvalds
2020-12-26 21:07 ` Linus Torvalds
2020-12-26 21:41 ` Matthew Wilcox
2020-12-09 16:39 ` [PATCH 2/2] arm64: mm: Implement arch_wants_old_faultaround_pte() Will Deacon
2020-12-09 18:35 ` Catalin Marinas
2020-12-09 18:46 ` Will Deacon
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='CAHk-=wjvHxQDet0=DTkqmYni_fgDsG=2_-idECFxnd+ECKdg_g@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=akpm@linux-foundation.org \
--cc=catalin.marinas@arm.com \
--cc=hughd@google.com \
--cc=jack@suse.cz \
--cc=kernel-team@android.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kirill@shutemov.name \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux@tometzki.de \
--cc=minchan@kernel.org \
--cc=vinmenon@codeaurora.org \
--cc=will@kernel.org \
--cc=willy@infradead.org \
/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;
as well as URLs for NNTP newsgroup(s).