From: Dan Williams <dan.j.williams@intel.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: David Hildenbrand <david@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
stable <stable@vger.kernel.org>,
Vishal Verma <vishal.l.verma@intel.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm/memory_hotplug: Fix remove_memory() lockdep splat
Date: Fri, 24 Jan 2020 10:04:52 -0800 [thread overview]
Message-ID: <CAPcyv4jcCnfGy5HcYimxcyF6v_Anw4nMdaNHQt4tMrqUaN70Rg@mail.gmail.com> (raw)
In-Reply-To: <20200124124512.GT29276@dhcp22.suse.cz>
On Fri, Jan 24, 2020 at 4:56 AM Michal Hocko <mhocko@kernel.org> wrote:
>
> On Fri 10-01-20 13:27:24, Dan Williams wrote:
> > On Fri, Jan 10, 2020 at 9:42 AM David Hildenbrand <david@redhat.com> wrote:
> [...]
> > > For your reference (roughly 5 months ago, so not that old)
> > >
> > > https://lkml.kernel.org/r/20190724143017.12841-1-david@redhat.com
> >
> > Oh, now I see the problem. You need to add that lock so far away from
> > the __add_memory() to avoid lock inversion problems with the
> > acpi_scan_lock. The organization I was envisioning would not work
> > without deeper refactoring.
>
> Sorry to come back to this late. Has this been resolved?
The mem_hotplug_lock lockdep splat fix in this patch has not landed.
David and I have not quite come to consensus on how to resolve online
racing removal. IIUC David wants that invalidation to be
pages_correctly_probed(), I would prefer it to be directly tied to the
object, struct memory_block, that remove_memory_block_devices() has
modified, mem->section_count = 0.
...or are you referring to the discussion about acpi_scan_lock()? I
came around to agreeing with your position that documenting was better
than adding superfluous locking especially because the
acpi_scan_lock() is take so far away from where the device_hotplug
lock is needed.
next prev parent reply other threads:[~2020-01-24 18:05 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 4:30 [PATCH] mm/memory_hotplug: Fix remove_memory() lockdep splat Dan Williams
2020-01-10 9:10 ` David Hildenbrand
2020-01-10 16:42 ` Dan Williams
2020-01-10 16:54 ` David Hildenbrand
2020-01-10 16:57 ` David Hildenbrand
2020-01-10 17:24 ` Dan Williams
2020-01-10 17:29 ` David Hildenbrand
2020-01-10 17:33 ` Dan Williams
2020-01-10 17:36 ` David Hildenbrand
2020-01-10 17:39 ` Dan Williams
2020-01-10 17:42 ` David Hildenbrand
2020-01-10 21:27 ` Dan Williams
2020-01-24 12:45 ` Michal Hocko
2020-01-24 18:04 ` Dan Williams [this message]
2020-01-24 18:13 ` David Hildenbrand
2020-01-27 13:47 ` Michal Hocko
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=CAPcyv4jcCnfGy5HcYimxcyF6v_Anw4nMdaNHQt4tMrqUaN70Rg@mail.gmail.com \
--to=dan.j.williams@intel.com \
--cc=akpm@linux-foundation.org \
--cc=dave.hansen@linux.intel.com \
--cc=david@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=pasha.tatashin@soleen.com \
--cc=stable@vger.kernel.org \
--cc=vishal.l.verma@intel.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).