From: "Luck, Tony" <tony.luck@intel.com>
To: Shuai Xue <xueshuai@linux.alibaba.com>,
David Laight <David.Laight@ACULAB.COM>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>,
Andrew Morton <akpm@linux-foundation.org>,
Miaohe Lin <linmiaohe@huawei.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Williams, Dan J" <dan.j.williams@intel.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: RE: [PATCH v2] mm, hwpoison: Try to recover from copy-on write faults
Date: Fri, 21 Oct 2022 16:30:50 +0000 [thread overview]
Message-ID: <SJ1PR11MB6083CEDBA2719825A1AD325EFC2D9@SJ1PR11MB6083.namprd11.prod.outlook.com> (raw)
In-Reply-To: <dda2321d-15f4-342a-2fbe-5c535858eb34@linux.alibaba.com>
>> But maybe it is some RMW instruction ... then, if all the above options didn't happen ... we
>> could get another machine check from the same address. But then we just follow the usual
>> recovery path.
> Let assume the instruction that cause the COW is in the 63/64 case, aka,
> it is writing a different cache line from the poisoned one. But the new_page
> allocated in COW is dropped right? So might page fault again?
It can, but this should be no surprise to a user that has a signal handler for
a h/w event (SIGBUS, SIGSEGV, SIGILL) that does nothing to address the
problem, but simply returns to re-execute the same instruction that caused
the original trap.
There may be badly written signal handlers that do this. But they just cause
pain for themselves. Linux can keep taking the traps and fixing things up and
sending a new signal over and over.
In this case that loop may involve taking the machine check again, so some
extra pain for the kernel, but recoverable machine checks on Intel/x86 switched
from broadcast to delivery to just the logical CPU that tried to consume the poison
a few generations back. So only a bit more painful than a repeated page fault.
-Tony
WARNING: multiple messages have this Message-ID (diff)
From: "Luck, Tony" <tony.luck@intel.com>
To: Shuai Xue <xueshuai@linux.alibaba.com>,
David Laight <David.Laight@ACULAB.COM>
Cc: Miaohe Lin <linmiaohe@huawei.com>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Nicholas Piggin <npiggin@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"Williams, Dan J" <dan.j.williams@intel.com>
Subject: RE: [PATCH v2] mm, hwpoison: Try to recover from copy-on write faults
Date: Fri, 21 Oct 2022 16:30:50 +0000 [thread overview]
Message-ID: <SJ1PR11MB6083CEDBA2719825A1AD325EFC2D9@SJ1PR11MB6083.namprd11.prod.outlook.com> (raw)
In-Reply-To: <dda2321d-15f4-342a-2fbe-5c535858eb34@linux.alibaba.com>
>> But maybe it is some RMW instruction ... then, if all the above options didn't happen ... we
>> could get another machine check from the same address. But then we just follow the usual
>> recovery path.
> Let assume the instruction that cause the COW is in the 63/64 case, aka,
> it is writing a different cache line from the poisoned one. But the new_page
> allocated in COW is dropped right? So might page fault again?
It can, but this should be no surprise to a user that has a signal handler for
a h/w event (SIGBUS, SIGSEGV, SIGILL) that does nothing to address the
problem, but simply returns to re-execute the same instruction that caused
the original trap.
There may be badly written signal handlers that do this. But they just cause
pain for themselves. Linux can keep taking the traps and fixing things up and
sending a new signal over and over.
In this case that loop may involve taking the machine check again, so some
extra pain for the kernel, but recoverable machine checks on Intel/x86 switched
from broadcast to delivery to just the logical CPU that tried to consume the poison
a few generations back. So only a bit more painful than a repeated page fault.
-Tony
next prev parent reply other threads:[~2022-10-21 16:31 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-17 23:42 [RFC PATCH] mm, hwpoison: Recover from copy-on-write machine checks Tony Luck
2022-10-18 8:43 ` HORIGUCHI NAOYA(堀口 直也)
2022-10-18 17:52 ` Luck, Tony
2022-10-19 17:08 ` [PATCH v2] mm, hwpoison: Try to recover from copy-on write faults Tony Luck
2022-10-19 17:08 ` Tony Luck
2022-10-19 17:45 ` Dan Williams
2022-10-19 17:45 ` Dan Williams
2022-10-19 20:30 ` Luck, Tony
2022-10-19 20:30 ` Luck, Tony
2022-10-20 1:57 ` Shuai Xue
2022-10-20 1:57 ` Shuai Xue
2022-10-20 20:05 ` Tony Luck
2022-10-20 20:05 ` Tony Luck
2022-10-21 1:38 ` Miaohe Lin
2022-10-21 1:38 ` Miaohe Lin
2022-10-21 3:57 ` Luck, Tony
2022-10-21 3:57 ` Luck, Tony
2022-10-21 1:52 ` Shuai Xue
2022-10-21 1:52 ` Shuai Xue
2022-10-21 4:08 ` Tony Luck
2022-10-21 4:08 ` Tony Luck
2022-10-21 4:11 ` David Laight
2022-10-21 4:11 ` David Laight
2022-10-21 4:41 ` Luck, Tony
2022-10-21 4:41 ` Luck, Tony
2022-10-21 9:29 ` Shuai Xue
2022-10-21 9:29 ` Shuai Xue
2022-10-21 16:30 ` Luck, Tony [this message]
2022-10-21 16:30 ` Luck, Tony
2022-10-23 15:04 ` Shuai Xue
2022-10-23 15:04 ` Shuai Xue
2022-10-21 6:57 ` Shuai Xue
2022-10-21 6:57 ` Shuai Xue
2022-10-21 20:01 ` [PATCH v3 0/2] Copy-on-write poison recovery Tony Luck
2022-10-21 20:01 ` Tony Luck
2022-10-21 20:01 ` [PATCH v3 1/2] mm, hwpoison: Try to recover from copy-on write faults Tony Luck
2022-10-21 20:01 ` Tony Luck
2022-10-25 5:46 ` HORIGUCHI NAOYA(堀口 直也)
2022-10-25 5:46 ` HORIGUCHI NAOYA(堀口 直也)
2022-10-28 2:11 ` Miaohe Lin
2022-10-28 2:11 ` Miaohe Lin
2022-10-28 16:09 ` Luck, Tony
2022-10-28 16:09 ` Luck, Tony
2022-11-02 14:27 ` Alexander Potapenko
2022-11-02 14:27 ` Alexander Potapenko
2022-11-02 14:30 ` Alexander Potapenko
2022-11-02 14:30 ` Alexander Potapenko
2022-10-21 20:01 ` [PATCH v3 2/2] mm, hwpoison: When copy-on-write hits poison, take page offline Tony Luck
2022-10-21 20:01 ` Tony Luck
2022-10-28 2:28 ` Miaohe Lin
2022-10-28 2:28 ` Miaohe Lin
2022-10-28 16:13 ` Luck, Tony
2022-10-28 16:13 ` Luck, Tony
2022-10-29 1:55 ` Miaohe Lin
2022-10-29 1:55 ` Miaohe Lin
2022-10-23 15:52 ` [PATCH v3 0/2] Copy-on-write poison recovery Shuai Xue
2022-10-23 15:52 ` Shuai Xue
2022-10-26 5:19 ` Shuai Xue
2022-10-26 5:19 ` Shuai Xue
2022-10-31 20:10 ` [PATCH v4 " Tony Luck
2022-10-31 20:10 ` Tony Luck
2022-10-31 20:10 ` [PATCH v4 1/2] mm, hwpoison: Try to recover from copy-on write faults Tony Luck
2022-10-31 20:10 ` Tony Luck
2022-10-31 20:10 ` [PATCH v4 2/2] mm, hwpoison: When copy-on-write hits poison, take page offline Tony Luck
2022-10-31 20:10 ` Tony Luck
2023-05-18 21:49 ` Jane Chu
2023-05-18 22:10 ` Luck, Tony
2023-05-19 7:28 ` Greg Kroah-Hartman
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=SJ1PR11MB6083CEDBA2719825A1AD325EFC2D9@SJ1PR11MB6083.namprd11.prod.outlook.com \
--to=tony.luck@intel.com \
--cc=David.Laight@ACULAB.COM \
--cc=akpm@linux-foundation.org \
--cc=christophe.leroy@csgroup.eu \
--cc=dan.j.williams@intel.com \
--cc=linmiaohe@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=naoya.horiguchi@nec.com \
--cc=npiggin@gmail.com \
--cc=willy@infradead.org \
--cc=xueshuai@linux.alibaba.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.