From: Borislav Petkov <bp@alien8.de>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: "x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Aili Yao" <yaoaili@kingsoft.com>,
"HORIGUCHI NAOYA( 堀口 直也)" <naoya.horiguchi@nec.com>
Subject: Re: [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison
Date: Wed, 14 Apr 2021 15:05:09 +0200 [thread overview]
Message-ID: <20210414130509.GF10709@zn.tnic> (raw)
In-Reply-To: <bd3dbae888584ce58a8d6e4b549b29ce@intel.com>
On Tue, Apr 13, 2021 at 04:13:03PM +0000, Luck, Tony wrote:
> Even if no applications ever do anything with it, it is still useful to avoid
> crashing the whole system and just terminate one application/guest.
True.
> There's one more item on my long term TODO list. Add fixups so that
> copy_to_user() from poison in the page cache doesn't crash, but just
> checks to see if the page was clean .. .in which case re-read from the
> filesystem into a different physical page and retire the old page ... the
> read can now succeed. If the page is dirty, then fail the read (and retire
> the page ... need to make sure filesystem knows the data for the page
> was lost so subsequent reads return -EIO or something).
Makes sense.
> Page cache occupies enough memory that it is a big enough
> source of system crashes that could be avoided. I'm not sure
> if there are any other obvious cases after this ... it all gets into
> diminishing returns ... not really worth it to handle a case that
> only occupies 0.00002% of memory.
Ack.
> See above. With core counts continuing to increase, the cloud service
> providers really want to see fewer events that crash the whole physical
> machine (taking down dozens, or hundreds, of guest VMs).
Yap.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-04-14 13:05 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-26 0:02 [RFC 0/4] Fix machine check recovery for copy_from_user Tony Luck
2021-03-26 0:02 ` [PATCH 1/4] x86/mce: Fix copyin code to return -EFAULT on machine check Tony Luck
2021-04-06 19:24 ` Borislav Petkov
2021-03-26 0:02 ` [PATCH 2/4] mce/iter: Check for copyin failure & return error up stack Tony Luck
2021-03-26 0:02 ` [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison Tony Luck
2021-04-07 21:18 ` Borislav Petkov
2021-04-07 21:43 ` Luck, Tony
2021-04-08 8:49 ` Borislav Petkov
2021-04-08 17:08 ` Luck, Tony
2021-04-13 10:07 ` Borislav Petkov
2021-04-13 16:13 ` Luck, Tony
2021-04-14 13:05 ` Borislav Petkov [this message]
2021-03-26 0:02 ` [PATCH 4/4] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-04-08 13:36 ` Borislav Petkov
2021-04-08 16:06 ` Luck, Tony
2021-04-08 2:13 ` [RFC 0/4] Fix machine check recovery for copy_from_user Aili Yao
2021-04-08 14:39 ` Luck, Tony
2021-04-09 6:49 ` Aili Yao
2021-04-14 5:47 [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison Jue Wang
2021-04-14 13:10 ` Borislav Petkov
2021-04-14 14:46 ` Jue Wang
2021-04-14 15:35 ` Borislav Petkov
2021-04-19 20:32 Jue Wang
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