From: Masami Hiramatsu <mhiramat@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Ingo Molnar <mingo@elte.hu>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
systemtap-ml <systemtap@sources.redhat.com>
Subject: Re: [BUGFIX][PATCH -tip] x86: fix text_poke to handle highmem pages
Date: Mon, 06 Apr 2009 13:44:37 -0400 [thread overview]
Message-ID: <49DA3F85.7050302@redhat.com> (raw)
In-Reply-To: <20090406173238.GA31867@Krystal>
Mathieu Desnoyers wrote:
> * Masami Hiramatsu (mhiramat@redhat.com) wrote:
>> Fix a bug in text_poke to handle highmem pages, because module
>> text pages are possible to be highmem pages on x86-32.
>> In that case, since fixmap can't handle those pages, text_poke
>> uses kmap_atomic.
>>
>
> Hrm, can you remind me what would be the downside of using kmap_atomic
> in every scenarios (highmem and non-highmem) then ?
kmap_atomic can handle only highmem pages. If you passes lowmem pages,
it returns just original vaddr of it. (because kmap is only for
highmem support)
>
> I would try to avoid "special cases" as much as possible, because they
> just make problems harder to reproduce.
Actually, this bug is a special case because it happens only on PAE kernel.
>
> The idea would be to either add fixmap highmem support, or to simply use
> kmap_atomic() for all cases until we add fixmap highmem support.
>
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2009-04-06 17:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-04 14:34 [BUG][-tip] kprobes on module functions hits kernel BUG in text_poke on x86-32 Masami Hiramatsu
2009-04-04 15:42 ` Mathieu Desnoyers
2009-04-04 18:28 ` Masami Hiramatsu
2009-04-04 19:04 ` Masami Hiramatsu
2009-04-05 3:46 ` Masami Hiramatsu
2009-04-05 3:49 ` Masami Hiramatsu
2009-04-06 17:11 ` [BUGFIX][PATCH -tip] x86: fix text_poke to handle highmem pages Masami Hiramatsu
2009-04-06 17:32 ` Mathieu Desnoyers
2009-04-06 17:44 ` Masami Hiramatsu [this message]
2009-04-06 17:58 ` Mathieu Desnoyers
2009-04-06 20:23 ` Masami Hiramatsu
2009-04-08 12:31 ` Ingo Molnar
2009-04-08 14:57 ` Masami Hiramatsu
2009-04-08 14:59 ` Ingo Molnar
2009-04-09 17:55 ` [BUGFIX][PATCH] x86: fix set_fixmap to use phys_addr_t Masami Hiramatsu
2009-04-09 18:46 ` Mathieu Desnoyers
2009-04-09 21:52 ` Masami Hiramatsu
2009-04-10 14:06 ` [tip:x86/urgent] " Masami Hiramatsu
2009-04-10 15:20 ` Masami Hiramatsu
2009-04-10 16:05 ` Mathieu Desnoyers
2009-04-10 17:48 ` Masami Hiramatsu
2009-04-10 18:30 ` Masami Hiramatsu
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