Re: Core file size?

[linux err]

This patch fixed it.

http://lkml.org/lkml/2005/6/13/204

The ELF core dump code has one use of off_t when
writing out segments.  Some
of the segments may be passed the 2GB limit of an
off_t, even on a 32-bit
system, so it's important to use loff_t instead.  This
fixes a corrupted
core dump in the bigcore test in GDB's testsuite.

Signed-off-by: Daniel Jacobowitz
<dan@xxxxxxxxxxxxxxxx>

Index: linux-2.6.11/fs/binfmt_elf.c
===================================================================
--- linux-2.6.11.orig/fs/binfmt_elf.c	2005-06-09
16:38:17.000000000 -0400
+++ linux-2.6.11/fs/binfmt_elf.c	2005-06-10
00:10:52.000000000 -0400
@@ -1125,7 +1125,7 @@ static int dump_write(struct
file *file,
 	return file->f_op->write(file, addr, nr,
&file->f_pos) == nr;
 }
 
-static int dump_seek(struct file *file, off_t off)
+static int dump_seek(struct file *file, loff_t off)
 {
 	if (file->f_op->llseek) {
 		if (file->f_op->llseek(file, off, 0) != off)
-- 




--- Jesper Juhl <jesper.juhl@xxxxxxxxx> wrote:

> On 30/11/06, linux err <linux_err@xxxxxxxxx> wrote:
> > Does anyone know what determines the size of a
> core
> > dump? I have a process running out of memory (it
> > allocates about 3GB) - but the size of core varies
> > (between 2-3GB) depending on how much the process
> > wrote on the allocated memory.
> >
> 
> Makes perfect sense. The core dump contains the
> memory of the process,
> so if the process has 3GB in use then the core file
> will be 3GB.
> 
> You can limit the size of core dumps with "ulimit
> -c"
> 
> 
> > Also, the time it takes to write the core (same
> size)
> > varies??
> >
> Could be many reasons for that. If the load on the
> machine varies the
> time to perform any given action will vary as well.
> 
> 
> > I briefly looked at elf_core_dump and
> get_user_pages()
> > in binfmt_elf.c. Is there any documentation on
> this?
> > Or anyone knows how it works?
> >
> http://x86.ddj.com/ftp/manuals/tools/elf.pdf
> http://en.wikipedia.org/wiki/Core_dump
> 
> 
> -- 
> Jesper Juhl <jesper.juhl@xxxxxxxxx>
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