Re: [RFC] Strange do_munmap in mmap_region

[Wang YanQing <udknight@gmail.com>]

On Thu, Mar 19, 2015 at 06:36:54PM +0300, Konstantin Khlebnikov wrote:
> > Assme process has vma in region 4096-8192, one page size, mapped to
> > a file's first 4096 bytes, then a new map want to create vma in range
> > 0-8192 to map 4096-1288 in file, please tell me what's your meaning:
> > "so everything what was here before is unmapped in process"?
> >
> > Why we can just delete old vma for first 4096 size in file which reside
> > in range 4096-8192 without notify user process? And create the new vma
> > to occupy range 0-8192, do you think "everything" is really the same?
> 
> Old and new vmas are intersects? Then that means userpace asked to
> create new mapping at fixed address, so it tells kernel to unmap
> everything in that range. Without MAP_FIXED kernel always choose free area.
> 

Thanks, Konstantin Khlebnikov, you cure my headache :)

I haven't notice MAP_FIXED.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>