Re: CVS commit: src/sys/uvm

[yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi)]

hi,

> yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi) wrote:
>> >> > Log Message:
>> >> > amap_copy(): Keep the source amap locked until its lock has been
>> >> > copied.
>> >> 
>> >> btw, this code seems to assume that uvm_anfree does not release the
>> >> lock even temporarily while the comment on uvm_anfree1 says the
>> >> opposite.
>> > 
>> > http://www.netbsd.org/~rmind/uvm_anon_freelst.diff
>> > 
>> > Looks good?
>> 
>> i don't understand what it solves.  can you explain a little?
> 
> Here is the updated patch after your changes:
> 
> http://www.netbsd.org/~rmind/uvm_anon_freelst2.diff
> 
> As you noted, uvm_anfree() can temporarily release the amap lock - that can
> happen in amap_copy().  Patch closes the race by moving uvm_anfree() further,
> and changes the semantics of the function, now called uvm_anon_freelst(), to
> return with amap lock released (plus free anons without lock held).

the temporary release of the amap lock is only for O->A loan
which you disabled, isn't it?

YAMAMOTO Takashi

> 
> -- 
> Mindaugas