Re: [PATCH 3/4] coredump: ELF-FDPIC: enable to omit anonymous shared memory
From: Kawai, Hidehiro
Date: Tue Feb 20 2007 - 04:45:54 EST
Thank you for your comments.
David Howells wrote:
>> static int elf_fdpic_dump_segments(struct file *file, struct mm_struct *mm,
>>- size_t *size, unsigned long *limit)
>>+ size_t *size, unsigned long *limit,
>>+ unsigned int omit_anon_shared)
> Why are you passing it as an extra argument when you could just use
> mm->coredump_omit_anon_shared here:
>>+ if (!maydump(vma, omit_anon_shared))
> I wouldn't worry, were I you, about the setting changing whilst it's being
> used. If you are worried about that, you can probably do some locking against
Core dumping is separated two phases, one is the phase of writing
headers, the other is the phase of writing memory segments. If the
coredump_omit_anon_shared setting is changed between these two phases,
a corrupted core file will be generated because the offsets written
in headers don't match their bodies. So we need to use the same
setting in both phases.
I think that locking makes codes complex and generates overhead.
So I wouldn't like to use lock as far as possible. I think passing
the flag as an extra argument is the simplest implementation to
avoid the core file corruption.
Hitachi, Ltd., Systems Development Laboratory
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