Re: /proc/$pid/pagemap troubles
- From: Dave Hansen <haveblue@xxxxxxxxxx>
- Date: Tue, 31 Jul 2007 16:06:21 -0700
On Wed, 2007-08-01 at 00:58 +0200, Andreas Schwab wrote:
Matt Mackall <mpm@xxxxxxxxxxx> writes:
On Tue, Jul 31, 2007 at 01:36:14PM -0700, Dave Hansen wrote:
Since the pagemap code has a little header on it to help describe the
format, I wrote a little c program to parse its output. I get some
strange results. If I do this:
fd = open("/proc/1/pagemap", O_RDONLY);
count = read(fd, &endianness, 1);
count will always be 4.
Known bug, fixed in my pending and not-currently-working update. It
ought to return 0 for short reads.
That's not a good choice. Returning 0 means EOF, but there is actually
data to be read.
This should actually be pretty easy to fix. We have a nice PAGE_SIZE
buffer. So, if we are unaligned and would have overflowed the PAGE_SIZE
buffer, we return a short read.
If they ask for a <sizeof(unsigned long) read, we can copy that into the
PAGE_SIZE buffer, then just copy_to_user() the portion that was asked
for.
-- Dave
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- Re: /proc/$pid/pagemap troubles
- From: Andreas Schwab
- Re: /proc/$pid/pagemap troubles
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