On Thu, 27 Mar 2014 14:54:41 +0100
Michael Holzheu <holzheu at linux.vnet.ibm.com> wrote:
> On Thu, 27 Mar 2014 05:19:06 +0000
> Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp> wrote:
>
> > Hello Michael,
> >
> > >On Wed, 26 Mar 2014 10:55:07 +0100 (a/T)
> > >HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> wrote:
> > >
> > >> From: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> > >> Subject: [PATCH 2/2] makedumpfile: Use max_pfn from mem_map array
> > >> Date: Tue, 25 Mar 2014 17:14:20 +0100
> > >
> > >[snip]
> > >
> > >> > With this patch makedumpfile gets the maximum page frame number from
> > >> > the mem_map array and adjusts info->max_mapnr if this value is smaller
> > >> > than the value calculated from the ELF header.
> > >> >
> > >> > Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> > >> > ---
> > >> > makedumpfile.c | 14 +++++++++++++-
> > >> > 1 file changed, 13 insertions(+), 1 deletion(-)
> > >> >
> > >> > --- a/makedumpfile.c
> > >> > +++ b/makedumpfile.c
> > >> > @@ -2829,7 +2829,8 @@ get_mem_map_without_mm(void)
> > >> > int
> > >> > get_mem_map(void)
> > >> > {
> > >> > - int ret;
> > >> > + unsigned long max_pfn = 0;
> > >> > + int ret, i;
> > >>
> > >> Please define max_pfn as unsigned long long.
> > >
> > >Ok done.
> > >
> > >>
> > >> And for i,
> > >>
> > >> >
> > >> > switch (get_mem_type()) {
> > >> > case SPARSEMEM:
> > >> > @@ -2861,6 +2862,17 @@ get_mem_map(void)
> > >> > ret = FALSE;
> > >> > break;
> > >> > }
> > >> > + /*
> > >> > + * Adjust "max_mapnr" for the case that Linux uses less memory
> > >> > + * than is dumped. For example when "mem=" has been used for the
> > >> > + * dumped system.
> > >> > + */
> > >> > + for (i = 0; i < info->num_mem_map; i++) {
> > >>
> > >> info->num_mem_map is defined as unsigned int. I guess some warning
> > >> about comparison with different signedness occurs.
> > >
> > >Ah ok...
> > >
> > >With the default CFLAGS for makedumpfile-1.5.5 tarball I do not get
> > >any warning. When I add "-W" to CFLAGS, I get lots of warnings
> > >including the one you mentioned.
> > >
> > >Here the fixed patch:
> >
> > Thanks, I'll merge the fixed version into v1.5.6.
>
> Great!
I'm sorry to spoil the party, but this patch broke Xen dumps for me.
I'm getting an long series of these messages:
set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap91pbsO). Invalid argument
set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap91pbsO). Invalid argument
set_bitmap: Can't read the bitmap(/tmp/kdump_bitmap91pbsO). Invalid argument
...
In fact, it most likely broke all non-cyclic dumps.
That's because the bitmap length is calculated in prepare_bitmap_buffer
using info->max_mapnr, but create_1st_bitmap() still loops over all
PT_LOAD segments, calling set_bit_on_1st_bitmap() for each PFN. The
offset may easily fall beyond the bitmap size.
Petr T
