From: "Américo Wang" <xiyou.wangcong@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.6.33 pagemap endless read loop
Date: Sun, 10 Jan 2010 14:33:35 +0800 [thread overview]
Message-ID: <20100110063335.GA3005@hack> (raw)
In-Reply-To: <20100110020955.GB25323@basil.fritz.box>
On Sun, Jan 10, 2010 at 03:09:55AM +0100, Andi Kleen wrote:
>
>An LTP run on x86-64/2.6.33-rc3 run right now results in "proc01" hanging
>
>lr-x------ 1 root root 64 2010-01-10 02:28 7 -> /proc/2679/task/2679/pagemap
>
>strace shows an endless loop of
>
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 1024
>read(7, "\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0\0\0\0\0\6\0\0\0"..., 1024) = 10
>
>cat of that file hangs in the same way so it seems like a kernel bug.
>A cat of /proc/2679/pagemap also hangs, in fact any pagemap cat seems to.
>
Are you sure?
On my 32bit machine, it runs for a long time, but finally exits.
>From the document of pagemap, it is the mapping of all the virtual pages
of a process, on x86-32, it should be 4G/4K = 1024*1024 pages, also
that when you 'cat' it, tty layer is involved to display it too.
--
Live like a child, think like the god.
next prev parent reply other threads:[~2010-01-10 6:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-10 2:09 2.6.33 pagemap endless read loop Andi Kleen
2010-01-10 6:33 ` Américo Wang [this message]
2010-01-10 12:37 ` Andi Kleen
2010-01-12 5:59 ` Mike Galbraith
2010-01-12 15:32 ` Américo Wang
2010-01-12 16:28 ` Andi Kleen
2010-01-13 2:08 ` Américo Wang
[not found] ` <20100113141648.42eff724.akpm@linux-foundation.org>
[not found] ` <1263421562.29868.5000.camel@calx>
[not found] ` <20100113143055.7bea30c5.akpm@linux-foundation.org>
[not found] ` <1263423916.29868.5009.camel@calx>
[not found] ` <20100113151502.fa425247.akpm@linux-foundation.org>
[not found] ` <20100114055319.GA17671@localhost>
[not found] ` <20100113221013.b1beecb4.akpm@linux-foundation.org>
2010-01-14 8:06 ` Wu Fengguang
2010-01-14 8:30 ` Andi Kleen
2010-01-14 8:52 ` [PATCH] pagemap: early return on unmapped areas Wu Fengguang
2010-01-14 17:02 ` Matt Mackall
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