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From: Andi Kleen <andi@firstfloor.org>
To: linux-kernel@vger.kernel.org
Subject: 2.6.33 pagemap endless read loop
Date: Sun, 10 Jan 2010 03:09:55 +0100	[thread overview]
Message-ID: <20100110020955.GB25323@basil.fritz.box> (raw)


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.

I tried to revert the latest change from Horiguchi-san:

commit 5dc37642cbce34619e4588a9f0bdad1d2f870956
Author: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date:   Mon Dec 14 18:00:01 2009 -0800

    mm hugetlb: add hugepage support to pagemap

but that didn't fix it, so it must be something else.

Haven't done further bisect or anything, should be easy to reproduce.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.

             reply	other threads:[~2010-01-10  2:09 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-10  2:09 Andi Kleen [this message]
2010-01-10  6:33 ` Américo Wang
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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