On 3/30/21 3:56 PM, Alistair Popple wrote:
...
+1 for renaming "munlock*" items to "mlock*", where applicable. good grief.
At least the situation was weird enough to prompt further investigation :)
Renaming to mlock* doesn't feel like the right solution to me either though. I
am not sure if you saw me responding to myself earlier but I am thinking
renaming try_to_munlock() -> page_mlocked() and try_to_munlock_one() ->
page_mlock_one() might be better. Thoughts?
Quite confused by this naming idea. Because: try_to_munlock() returns
void, so a boolean-style name such as "page_mlocked()" is already not a
good fit.
Even more important, though, is that try_to_munlock() is mlock-ing the
page, right? Is there some subtle point I'm missing? It really is doing
an mlock to the best of my knowledge here. Although the kerneldoc
comment for try_to_munlock() seems questionable too:
/**
* try_to_munlock - try to munlock a page
* @page: the page to be munlocked
*
* Called from munlock code. Checks all of the VMAs mapping the page
* to make sure nobody else has this page mlocked. The page will be
* returned with PG_mlocked cleared if no other vmas have it mlocked.
*/
...because I don't see where, in *this* routine, it clears PG_mlocked!
Obviously we agree that a routine should be named based on what it does,
rather than on who calls it. So I think that still leads to:
try_to_munlock() --> try_to_mlock()
try_to_munlock_one() --> try_to_mlock_one()
Sorry if I'm missing something really obvious.
This is actually inspired from a suggestion in Documentation/vm/unevictable-
lru.rst which warns about this problem:
try_to_munlock() Reverse Map Scan
---------------------------------
.. warning::
[!] TODO/FIXME: a better name might be page_mlocked() - analogous to the
page_referenced() reverse map walker.
This is actually rather bad advice! page_referenced() returns an
int-that-is-really-a-boolean, whereas try_to_munlock(), at least as it
stands now, returns void. Usually when I'm writing a TODO item, I'm in a
hurry, and I think that's what probably happened here, too. :)
Although, it seems reasonable to tack such renaming patches onto the tail
end
of this series. But whatever works.
Unless anyone objects strongly I will roll the rename into this patch as there
is only one caller of try_to_munlock.
- Alistair
No objections here. :)
thanks,
--
John Hubbard
NVIDIA
