From: "Luck, Tony" <tony.luck@intel.com>
To: linux-ia64@vger.kernel.org
Subject: RE: [PATCH 2.4.23-pre8] Remove broken prefetching in free_one_pgd()
Date: Fri, 24 Oct 2003 22:16:59 +0000 [thread overview]
Message-ID: <marc-linux-ia64-106703405120029@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-106702916015259@msgid-missing>
> Tony> This patch was accepted into 2.5.55, attributed to "davej@uk".
> Tony> This code will prefetch from beyond the end of the page table
> Tony> being cleared ... which is clearly a bad thing if the page
> Tony> table in question is allocated from the last page of memory
> Tony> (or precedes a hole on a discontig mem system).
>
> Different arches behave differently, though. In the case of ia64,
> it'a always safe to prefetch (even with lfetch.fault).
Not quite always ... this was how I found the efi trim.bottom bug, since
Linux had allocated a pgd at 0xa00000-16k, and the lfetch that reached
out beyond the end of the page to the uncacheable address 0xa00000 took
an MCA.
A pgd in the last page of a granule that is followed by an uncacheable
address would do the same with lfetch.fault, wouldn't it?
-Tony
next prev parent reply other threads:[~2003-10-24 22:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-24 20:56 [PATCH 2.4.23-pre8] Remove broken prefetching in free_one_pgd() Luck, Tony
2003-10-24 22:01 ` David Mosberger
2003-10-24 22:16 ` Luck, Tony [this message]
2003-10-24 22:21 ` David Mosberger
2003-10-25 20:10 ` Pavel Machek
2003-10-26 14:51 ` Dave Jones
2003-10-27 9:52 ` Pavel Machek
2003-10-27 11:58 ` Dave Jones
2003-10-30 20:57 ` Bjorn Helgaas
2003-10-30 21:36 ` Luck, Tony
-- strict thread matches above, loose matches on Subject: below --
2003-10-24 20:56 Luck, Tony
2003-10-24 22:01 ` David Mosberger
2003-10-25 20:10 ` Pavel Machek
2003-10-26 14:51 ` Dave Jones
2003-10-27 9:52 ` Pavel Machek
2003-10-27 11:58 ` Dave Jones
2003-10-24 22:16 Luck, Tony
2003-10-24 22:21 ` David Mosberger
2003-10-30 20:57 ` Bjorn Helgaas
2003-10-30 21:36 Luck, Tony
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