From: Aili Yao <yaoaili@kingsoft.com>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>,
"Oscar Salvador" <osalvador@suse.de>,
"david@redhat.com" <david@redhat.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"bp@alien8.de" <bp@alien8.de>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"yangfeng1@kingsoft.com" <yangfeng1@kingsoft.com>,
yaoaili@kingsoft.com
Subject: Re: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned
Date: Wed, 3 Mar 2021 16:39:12 +0800 [thread overview]
Message-ID: <20210303163912.3d508e0f@alex-virtual-machine> (raw)
In-Reply-To: <20210303115710.2e9f8e23@alex-virtual-machine>
Hi tony:
> On Tue, 2 Mar 2021 19:39:53 -0800
> "Luck, Tony" <tony.luck@intel.com> wrote:
>
> > On Fri, Feb 26, 2021 at 10:59:15AM +0800, Aili Yao wrote:
> > > Hi naoya, tony:
> > > > >
> > > > > Idea for what we should do next ... Now that x86 is calling memory_failure()
> > > > > from user context ... maybe parallel calls for the same page should
> > > > > be blocked until the first caller completes so we can:
> > > > > a) know that pages are unmapped (if that happens)
> > > > > b) all get the same success/fail status
> > > >
> > > > One memory_failure() call changes the target page's status and
> > > > affects all mappings to all affected processes, so I think that
> > > > (ideally) we don't have to block other threads (letting them
> > > > early return seems fine). Sometimes memory_failure() fails,
> > > > but even in such case, PG_hwpoison is set on the page and other
> > > > threads properly get SIGBUSs with this patch, so I think that
> > > > we can avoid the worst scenario (like system stall by MCE loop).
> > > >
> > > I agree with naoya's point, if we block for this issue, Does this change the result
> > > that the process should be killed? Or is there something other still need to be considered?
> >
> > Ok ... no blocking ...
I do think about blocking method and the error address issue with sigbus,here is my opinion, maybe helpful:
For blocking, if we block here, there are some undefine work i think should be done.
As we don't know the process B triggering this error again is early-kill or not, so the previous memory_failure() call may
not add B on kill_list, even if B is on kill_list, the error level for B is not proper set, as B should get an AR SIGBUS;
So we can't just wait, We must have some logic adding the process B to kill list, and as this is an AR error
another change should be done to current code, we need more logic in kill_proc or some other place.
Even if all the work is done right. There is one more serious scenario though, we even don't know the current step the previous memory_failure() is on,
So previous modification may not be usefull at all; When this scenario happens, what we can do? block or return ?
if finally we return, an error code should be taken back; so we have to go to error process logic and a signal without right address will be sent;
For error address with sigbus, i think this is not an issue resulted by the patch i post, before my patch, the issue is already there.
I don't find a realizable way to get the correct address for same reason --- we don't know whether the page mapping is there or not when
we got to kill_me_maybe(), in some case, we may get it, but there are a lot of parallel issue need to consider, and if failed we have to fallback
to the error brach again, remaining current code may be an easy option;
Any methods or patchs can solve the issue in a better way is OK to me, i want this issue fixed and in more complete way!
--
Thanks!
Aili Yao
next prev parent reply other threads:[~2021-03-04 0:29 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210224151619.67c29731@alex-virtual-machine>
[not found] ` <20210224103105.GA16368@linux>
[not found] ` <20210225114329.4e1a41c6@alex-virtual-machine>
[not found] ` <20210225112818.GA10141@hori.linux.bs1.fc.nec.co.jp>
[not found] ` <20210225113930.GA7227@localhost.localdomain>
[not found] ` <20210225123806.GA15006@hori.linux.bs1.fc.nec.co.jp>
[not found] ` <20210225181542.GA178925@agluck-desk2.amr.corp.intel.com>
[not found] ` <20210226021907.GA27861@hori.linux.bs1.fc.nec.co.jp>
2021-02-26 2:59 ` [PATCH] mm,hwpoison: return -EBUSY when page already poisoned Aili Yao
2021-03-03 3:39 ` Luck, Tony
2021-03-03 3:57 ` Aili Yao
2021-03-03 8:39 ` Aili Yao [this message]
2021-03-03 15:41 ` Luck, Tony
2021-03-04 2:16 ` Aili Yao
2021-03-04 4:19 ` Aili Yao
2021-03-04 6:45 ` Aili Yao
2021-03-04 23:57 ` Luck, Tony
2021-03-05 1:30 ` Aili Yao
2021-03-05 1:36 ` Aili Yao
2021-03-05 22:11 ` Luck, Tony
2021-03-08 6:45 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-08 18:54 ` Luck, Tony
2021-03-08 22:38 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-08 22:55 ` [PATCH] mm/memory-failure: Use a mutex to avoid memory_failure() races Luck, Tony
2021-03-08 23:42 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-09 2:04 ` Aili Yao
2021-03-09 6:04 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-09 6:35 ` [PATCH v2] mm,hwpoison: return -EBUSY when page already poisoned Aili Yao
2021-03-09 8:28 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-09 20:01 ` Luck, Tony
2021-03-10 8:05 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-13 1:55 ` Jue Wang
2021-03-10 8:01 ` Aili Yao
2021-03-09 6:38 ` [PATCH] mm/memory-failure: Use a mutex to avoid memory_failure() races Aili Yao
2021-03-05 15:55 ` [PATCH] mm,hwpoison: return -EBUSY when page already poisoned Luck, Tony
2021-03-10 6:10 ` Aili Yao
2021-03-11 8:55 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-11 11:23 ` Aili Yao
2021-03-11 17:05 ` Luck, Tony
2021-03-12 5:55 ` Aili Yao
2021-03-12 16:29 ` Luck, Tony
2021-03-12 23:48 ` Luck, Tony
2021-03-16 6:42 ` HORIGUCHI NAOYA(堀口 直也)
2021-03-16 7:54 ` Aili Yao
2021-03-17 0:29 ` Luck, Tony
2021-03-17 9:07 ` Aili Yao
2021-03-17 7:48 ` Aili Yao
2021-03-17 8:23 ` Aili Yao
[not found] ` <20210226105250.3a15e35c@alex-virtual-machine>
2021-02-26 17:58 ` Luck, Tony
2021-03-02 4:32 ` Aili Yao
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