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 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).