linux-kernel - Re: [PATCH v3 0/2] Copy-on-write poison recovery

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Date:   Sun, 23 Oct 2022 23:52:04 +0800
From:   Shuai Xue <xueshuai@...ux.alibaba.com>
To:     Tony Luck <tony.luck@...el.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Miaohe Lin <linmiaohe@...wei.com>,
        Matthew Wilcox <willy@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 0/2] Copy-on-write poison recovery



在 2022/10/22 AM4:01, Tony Luck 写道:
> Part 1 deals with the process that triggered the copy on write
> fault with a store to a shared read-only page. That process is
> send a SIGBUS with the usual machine check decoration to specify
> the virtual address of the lost page, together with the scope.
> 
> Part 2 sets up to asynchronously take the page with the uncorrected
> error offline to prevent additional machine check faults. H/t to
> Miaohe Lin <linmiaohe@...wei.com> and Shuai Xue <xueshuai@...ux.alibaba.com>
> for pointing me to the existing function to queue a call to
> memory_failure().
> 
> On x86 there is some duplicate reporting (because the error is
> also signalled by the memory controller as well as by the core
> that triggered the machine check). Console logs look like this:
> 
> [ 1647.723403] mce: [Hardware Error]: Machine check events logged
> 	Machine check from kernel copy routine
> 
> [ 1647.723414] MCE: Killing einj_mem_uc:3600 due to hardware memory corruption fault at 7f3309503400
> 	x86 fault handler sends SIGBUS to child process
> 
> [ 1647.735183] Memory failure: 0x905b92d: recovery action for dirty LRU page: Recovered
> 	Async call to memory_failure() from copy on write path

The recovery action might also be handled asynchronously in CMCI uc_decode_notifier
handler signaled by memory controller, right?

I have a one more memory failure log than yours.

[ 3187.485742] MCE: Killing einj_mem_uc:31746 due to hardware memory corruption fault at 7fc4bf7cf400
[ 3187.740620] Memory failure: 0x1a3b80: recovery action for dirty LRU page: Recovered
	uc_decode_notifier() processes memory controller report

[ 3187.748272] Memory failure: 0x1a3b80: already hardware poisoned
	Workqueue: events memory_failure_work_func // queued by ghes_do_memory_failure

[ 3187.754194] Memory failure: 0x1a3b80: already hardware poisoned
	Workqueue: events memory_failure_work_func // queued by __wp_page_copy_user

[ 3188.615920] MCE: Killing einj_mem_uc:31745 due to hardware memory corruption fault at 7fc4bf7cf400

Best Regards,
Shuai

> 
> [ 1647.748397] Memory failure: 0x905b92d: already hardware poisoned
> 	uc_decode_notifier() processes memory controller report
> 
> [ 1647.761313] MCE: Killing einj_mem_uc:3599 due to hardware memory corruption fault at 7f3309503400
> 	Parent process tries to read poisoned page. Page has been unmapped, so
> 	#PF handler sends SIGBUS
> 
> 
> Tony Luck (2):
>   mm, hwpoison: Try to recover from copy-on write faults
>   mm, hwpoison: When copy-on-write hits poison, take page offline
> 
>  include/linux/highmem.h | 24 ++++++++++++++++++++++++
>  include/linux/mm.h      |  5 ++++-
>  mm/memory.c             | 32 ++++++++++++++++++++++----------
>  3 files changed, 50 insertions(+), 11 deletions(-)
>