Commit 608e8e66 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds

mm: add a gfp-translate script to help understand page allocation failure reports

The page allocation failure messages include a line that looks like

page allocation failure. order:1, mode:0x4020

The mode is easy to translate but irritating for the lazy and a bit error
prone.  This patch adds a very simple helper script gfp-translate for the
mode: portion of the page allocation failure messages.  An example usage
looks like

  mel@machina:~/linux-2.6 $ scripts/gfp-translate 0x4020
  Source: /home/mel/linux-2.6
  Parsing: 0x4020
  #define __GFP_HIGH	(0x20)	/* Should access emergency pools? */
  #define __GFP_COMP	(0x4000) /* Add compound page metadata */

The script is not a work of art but it has come in handy for me a few
times so I thought I would share.

[akpm@linux-foundation.org: clarify an error message]
Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 168f5ac6
#!/bin/bash
# Translate the bits making up a GFP mask
# (c) 2009, Mel Gorman <mel@csn.ul.ie>
# Licensed under the terms of the GNU GPL License version 2
SOURCE=
GFPMASK=none
# Helper function to report failures and exit
die() {
echo ERROR: $@
if [ "$TMPFILE" != "" ]; then
rm -f $TMPFILE
fi
exit -1
}
usage() {
echo "usage: gfp-translate [-h] [ --source DIRECTORY ] gfpmask"
exit 0
}
# Parse command-line arguements
while [ $# -gt 0 ]; do
case $1 in
--source)
SOURCE=$2
shift 2
;;
-h)
usage
;;
--help)
usage
;;
*)
GFPMASK=$1
shift
;;
esac
done
# Guess the kernel source directory if it's not set. Preference is in order of
# o current directory
# o /usr/src/linux
if [ "$SOURCE" = "" ]; then
if [ -r "/usr/src/linux/Makefile" ]; then
SOURCE=/usr/src/linux
fi
if [ -r "`pwd`/Makefile" ]; then
SOURCE=`pwd`
fi
fi
# Confirm that a source directory exists
if [ ! -r "$SOURCE/Makefile" ]; then
die "Could not locate kernel source directory or it is invalid"
fi
# Confirm that a GFP mask has been specified
if [ "$GFPMASK" = "none" ]; then
usage
fi
# Extract GFP flags from the kernel source
TMPFILE=`mktemp -t gfptranslate-XXXXXX` || exit 1
grep "^#define __GFP" $SOURCE/include/linux/gfp.h | sed -e 's/(__force gfp_t)//' | sed -e 's/u)/)/' | grep -v GFP_BITS | sed -e 's/)\//) \//' > $TMPFILE
# Parse the flags
IFS="
"
echo Source: $SOURCE
echo Parsing: $GFPMASK
for LINE in `cat $TMPFILE`; do
MASK=`echo $LINE | awk '{print $3}'`
if [ $(($GFPMASK&$MASK)) -ne 0 ]; then
echo $LINE
fi
done
rm -f $TMPFILE
exit 0
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