Re: Solution (Re: [uml-devel] Re: Weird hostfs file corruption (mmap?))

[Jeff D. <jd...@ka...>]

Nice diagnosis.

hn...@ma... said:
> memset(buffer, 0, PAGE_CACHE_SIZE) just before the call to read_file
> in hostfs_readpage should address this problem I think. 

Yup.

> Note: A quick inspection of the hostfs writepage function makes me
> think there is another bug in flushing the last page of modified
> mmaped files with an even page size. 

Yeah, I'll make sure about that.

> I'm afraid I am not familiar enough with the kernel to quickly grasp that
> function.  What is the meaning of page->index?

md...@de... said:
> I'm afraid I am not familiar enough with the kernel to quickly grasp that
> function.  What is the meaning of page->index?

Unless Henrik is seeing something else, a quick look at that code suggests
that count == 0 for the last page of a file whose size is an exact multiple
of the page size.

md...@de... said:
> It does, thank you.  Now I have only the SIGTERM problem to deal with.

Put a breakpoint on send_sig_info conditional on sig == 15 and get a backtrace.
There shouldn't be too many SIGTERMs floating around the kernel, so that 
should provide a good clue.

				Jeff