Minchan Kim wrote:
Hi Konstantin,
It seems to be nice clean up to me and you are a volunteer we have been wanted
for a long time. Thanks!
I am one of people who really want to expand vm_flags to 64 bit but when KOSAKI
tried it, Linus said his concerning, I guess you already saw that.
He want to tidy vm_flags's usage up rather than expanding it.
Without the discussion about that, just expanding vm_flags would make us use
it up easily so that we might need more space.
Strictly speaking, my pachset does not expands vm_flags, it just prepares to this.
Anyway vm_flags_t looks better than hard-coded "unsigned long" and messy type-casts around it.
Readahead flags are good candidate to move into another space and arch-specific flags, I guess.
Another candidate I think of is THP flag. It's just for only anonymous vma now
(But I am not sure we have a plan to support it for file-backed pages in future)
so we can move it to anon_vma or somewhere.
I think other guys might find more somethings
The point is that at least, we have to discuss about clean up current vm_flags's
use cases before expanding it unconditionally.
Seems like we can easily remove VM_EXECUTABLE
(count in mm->num_exe_file_vmas amount of vmas with vma->vm_file == mm->exe_file
instead of vmas with VM_EXECUTABLE bit)
And probably VM_CAN_NONLINEAR...
On Wed, Mar 21, 2012 at 10:56:07AM +0400, Konstantin Khlebnikov wrote:
There is good old tradition: every year somebody submit patches for extending
vma->vm_flags upto 64-bits, because there no free bits left on 32-bit systems.
previous attempts:
https://lkml.org/lkml/2011/4/12/24 (KOSAKI Motohiro)
https://lkml.org/lkml/2010/4/27/23 (Benjamin Herrenschmidt)
https://lkml.org/lkml/2009/10/1/202 (Hugh Dickins)
Here already exist special type for this: vm_flags_t, but not all code uses it.
So, before switching vm_flags_t from unsinged long to u64 we must spread
vm_flags_t everywhere and fix all possible type-casting problems.
There is no functional changes in this patch set,
it only prepares code for vma->vm_flags converting.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>