Re: [PATCH] Add a gfp-translate script to help understand page allocation failure reports

[Minchan Kim <minchan.kim@gmail.com>]

Hi, Mel.

How about handling it in kernel itself ?

I mean we can print human-readable pretty format instead of
non-understandable hex value. It can help us without knowing other's
people's machine configuration.

BTW, It would be better than now by your script.
Thanks for sharing good tip. :)

On Mon, Jun 8, 2009 at 10:29 PM, Mel Gorman<mel@csn.ul.ie> wrote:
> 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.
>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> ---
>  scripts/gfp-translate |   81 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
>
> diff --git a/scripts/gfp-translate b/scripts/gfp-translate
> new file mode 100755
> index 0000000..724db2d
> --- /dev/null
> +++ b/scripts/gfp-translate
> @@ -0,0 +1,81 @@
> +#!/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 "$SOURCE/Makefile" ]; then
> +       die "Could not locate source directory or it is invalid"
> +fi
> +
> +# Confirm that a GFP mask has been specified
> +if [ "$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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-- 
Kinds regards,
Minchan Kim

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