hi,
I am recently reading the source code of swapfile.c .
And I came to the logic of try_to_unuse() which try to swap in all
previously swapped pages and re-filling all the corresponding "pte"s.
The comment included in the code has already give some hint on the logic :
/ * When searching mms for an entry, a good strategy is to
* start at the first mm we freed the previous entry from
* (though actually we don't notice whether we or coincidence
* freed the entry). Initialize this start_mm with a hold.
... ....
However, I found that the local var "start_mm" should always equal to
&init_mm through out all the outer and inner "while" loop:
The only NOT-"&init_mm" assignment to "start_mm" is "start_mm =
new_start_mm;" and in turn the assignments to "new_start_mm" is
"new_start_mm = start_mm;" or "new_start_mm = mm;" but only when "mm
== &init_mm".
Also, "mm","start_mm","new_start_mm" are all local variables, which
means all the possible changes to them are in try_to_unuse().
So, if "start_mm" always equals &init_mm, why introduce "new_start_mm;" ?
Anyone please help me out, thanks in advance!
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