From: Jonathan Corbet <corbet@lwn.net>
To: Joerg Roedel <jroedel@suse.de>, Peilin Ye <yepeilin.cs@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
Muchun Song <songmuchun@bytedance.com>,
Cong Wang <cong.wang@bytedance.com>,
Peilin Ye <peilin.ye@bytedance.com>
Subject: Re: [PATCH RESEND v2] docs: x86: Remove obsolete information about x86_64 vmalloc() faulting
Date: Fri, 20 Aug 2021 11:14:52 -0600 [thread overview]
Message-ID: <87bl5srqb7.fsf@meer.lwn.net> (raw)
In-Reply-To: <YR4PNjIM3W5zkPnt@suse.de>
Joerg Roedel <jroedel@suse.de> writes:
> On Wed, Aug 18, 2021 at 03:01:23PM -0700, Peilin Ye wrote:
>> From: Peilin Ye <peilin.ye@bytedance.com>
>>
>> x86_64 vmalloc() mappings are no longer "synchronized" among page tables
>> via faulting since commit 6eb82f994026 ("x86/mm: Pre-allocate P4D/PUD
>> pages for vmalloc area"), since the corresponding P4D or PUD pages are
>> now preallocated at boot, by preallocate_vmalloc_pages(). Drop the
>> "lazily synchronized" description for less confusion.
>>
>> While this file is x86_64-specific, it is worth noting that things are
>> different for x86_32, where vmalloc()-related changes to `init_mm.pgd` are
>> synchronized to all page tables in the system during runtime, via
>> arch_sync_kernel_mappings(). Unfortunately, this synchronization is
>> subject to race condition, which is further handled via faulting, see
>> vmalloc_fault(). See commit 4819e15f740e ("x86/mm/32: Bring back vmalloc
>> faulting on x86_32") for more details.
>>
>> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
>> Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
>
> Reviewed-by: Joerg Roedel <jroedel@suse.de>
Applied, thanks.
jon
prev parent reply other threads:[~2021-08-20 17:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-18 22:01 [PATCH RESEND v2] docs: x86: Remove obsolete information about x86_64 vmalloc() faulting Peilin Ye
2021-08-19 7:58 ` Joerg Roedel
2021-08-20 17:14 ` Jonathan Corbet [this message]
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=87bl5srqb7.fsf@meer.lwn.net \
--to=corbet@lwn.net \
--cc=akpm@linux-foundation.org \
--cc=bp@alien8.de \
--cc=cong.wang@bytedance.com \
--cc=hpa@zytor.com \
--cc=jroedel@suse.de \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peilin.ye@bytedance.com \
--cc=songmuchun@bytedance.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
--cc=yepeilin.cs@gmail.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.