From: Andrew Morton <akpm@linux-foundation.org>
To: Huang Ying <ying.huang@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Hugh Dickins <hughd@google.com>,
"Xu, Pengfei" <pengfei.xu@intel.com>,
Christoph Hellwig <hch@lst.de>, Stefan Roesch <shr@devkernel.io>,
Tejun Heo <tj@kernel.org>, Xin Hao <xhao@linux.alibaba.com>,
Zi Yan <ziy@nvidia.com>, Yang Shi <shy828301@gmail.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Matthew Wilcox <willy@infradead.org>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH 0/3] migrate_pages: fix deadlock in batched synchronous migration
Date: Sat, 25 Feb 2023 20:55:43 -0800 [thread overview]
Message-ID: <20230225205543.5d56714d2145ac45da25369e@linux-foundation.org> (raw)
In-Reply-To: <20230224141145.96814-1-ying.huang@intel.com>
On Fri, 24 Feb 2023 22:11:42 +0800 Huang Ying <ying.huang@intel.com> wrote:
> Two deadlock bugs were reported for the migrate_pages() batching
> series.
"migrate_pages(): batch TLB flushing"
> Thanks Hugh and Pengfei. Analysis shows that if we have
> locked some other folios except the one we are migrating, it's not
> safe in general to wait synchronously, for example, to wait the
> writeback to complete or wait to lock the buffer head.
>
> So 1/3 fixes the deadlock in a simple way, where the batching support
> for the synchronous migration is disabled. The change is
> straightforward and easy to be understood. While 3/3 re-introduce the
> batching for synchronous migration via trying to migrate
> asynchronously in batch optimistically, then fall back to migrate
> synchronously one by one for fail-to-migrate folios. Test shows that
> this can restore the TLB flushing batching performance for synchronous
> migration effectively.
If anyone backports the "migrate_pages(): batch TLB flushing" series
into their kernels, they will want to know about such fixes. So we can
help them by providing suitable Link: tags.
Such a Link: may also be helpful to people who are performing git
bisection searches for some issue but who keep stumbling over the
issues which this series addresses.
Being lazy, I slapped
Fixes: 6f7d760e86fa ("migrate_pages: move THP/hugetlb migration support check to simplify code")
on all three, as this was the final patch in that series. Inaccurate,
but it means that these fixes will land in a suitable place if anyone
needs them.
next prev parent reply other threads:[~2023-02-26 4:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-24 14:11 Huang Ying
2023-02-24 14:11 ` [PATCH 1/3] migrate_pages: fix deadlock in batched migration Huang Ying
2023-02-28 6:13 ` Hugh Dickins
2023-02-28 7:22 ` Huang, Ying
2023-02-28 21:07 ` Hugh Dickins
2023-03-01 1:17 ` Huang, Ying
2023-02-24 14:11 ` [PATCH 2/3] migrate_pages: move split folios processing out of migrate_pages_batch() Huang Ying
2023-03-01 2:23 ` Baolin Wang
2023-03-01 6:35 ` Huang, Ying
2023-03-01 11:07 ` Baolin Wang
2023-02-24 14:11 ` [PATCH 3/3] migrate_pages: try migrate in batch asynchronously firstly Huang Ying
2023-02-28 6:36 ` Hugh Dickins
2023-02-28 7:45 ` Huang, Ying
2023-02-28 21:22 ` Hugh Dickins
2023-03-01 6:08 ` Huang, Ying
2023-03-01 6:46 ` Hugh Dickins
2023-03-01 7:10 ` Huang, Ying
2023-03-01 3:08 ` Baolin Wang
2023-03-01 6:18 ` Huang, Ying
2023-03-01 11:03 ` Baolin Wang
2023-02-26 4:55 ` Andrew Morton [this message]
2023-02-27 1:25 ` [PATCH 0/3] migrate_pages: fix deadlock in batched synchronous migration Huang, Ying
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=20230225205543.5d56714d2145ac45da25369e@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=baolin.wang@linux.alibaba.com \
--cc=hch@lst.de \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mike.kravetz@oracle.com \
--cc=pengfei.xu@intel.com \
--cc=shr@devkernel.io \
--cc=shy828301@gmail.com \
--cc=tj@kernel.org \
--cc=willy@infradead.org \
--cc=xhao@linux.alibaba.com \
--cc=ying.huang@intel.com \
--cc=ziy@nvidia.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